Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
GUANGQI CHEN Last modified date:2019.11.29

Professor / Geotechnic, Department of Civil & Structural Engineering, Graduate School of Engineering / Division for Experimental Natural Science / Faculty of Arts and Science


Papers
1. Xinyan Peng, Pengcheng Yu, Guangqi Chen, Mingyao Xia, Yingbin Zhang, CPU-accelerated explicit discontinuous deformation analysis and its application to landslide analysis, Applied Mathematical Modelling, 10.1016/j.apm.2019.07.028, 77, 216-234, 2020.01, An explicit discontinuous deformation analysis (DDA) that uses an explicit time integration procedure and an explicit calculation of interaction forces between blocks is proposed to overcome the limitations of conventional implicit DDA in simulating large-scale problems. The advantages of the explicit DDA are that (1) the global equilibrium equations are unnecessary to be assembled and the solving for unknowns of every block can be performed independently and conveniently, thereby reducing the computational effort and memory requirement; (2) the open-close iteration process is avoided because the interaction forces between blocks are calculated explicitly according to the initial information at the start of the current time step. The efficient parallel computing is very appropriate for the explicit DDA. To further improve its computational efficiency, the explicit DDA is paralleled based on OpenMP. The accuracy of the explicit DDA is verified through several numerical examples with analytical solutions, experimental data or field observation. Further, the computational efficiency is demonstrated by a series of models and the parallel speedup factor on 6 OpenMP threads is approximately 4.2. Conclusively, the explicit DDA is promising for analyzing blocky systems in large scale..
2. Pengcheng Yu, Guangqi Chen, Xinyan Peng, Longxiao Guo, Yingbin Zhang, Extension and application of Discontinuous Deformation Analysis with a damped contact spring model, International Journal of Rock Mechanics and Mining Sciences, 10.1016/j.ijrmms.2019.104123, 123, 2019.11, Discontinuous Deformation Analysis (DDA) is widely used in geological and geotechnical engineering. To provide an alternative approach to considering damping effect in dynamic analysis, a damped contact spring model is implemented. The model assumes that the damping component – linear dashpot - takes place in joints of DDA models. The normal and shear damping forces are determined according to the relative velocities of the two contacted points. A semi-analytical solution is also proposed to calculate damping coefficient from a given damping ratio. The viscous damping effect produced by the damped contact spring model is independent to step size. The proposed model is incorporated into DDA program, and then several classic damping dynamic examples are constructed to validate the contact model, showing good agreement with analytical solutions. After that, a seismic spectrum of a recorded ground motion is analyzed to show the contact model is suitable for response spectrum generation. Finally, the Donghekou landslide case is studied under different parameters, suggesting that the proper consideration of damping is essential to natural hazard analysis..
3. Pengcheng Yu, Yingbin Zhang, Xinyan Peng, Jinmei Wang, Guangqi Chen, John X. Zhao, Evaluation of impact force of rock landslides acting on structures using discontinuous deformation analysis, Computers and Geotechnics, 10.1016/j.compgeo.2019.103137, 114, 2019.10, Impact force evaluation of rock landslides acted on structures is important to the hazard prevention. This paper presents a numerical method to estimate the impact force on structures. An impact force model for the contact force on the given boundary, rather than the resultant force at the center of gravity is presented and incorporated into Discontinuous Deformation Analysis (DDA). The accuracy is verified by comparing simulation results with both analytical and experimental results. A case is then carried out to study the impact force of sliding mass acting on structures, showing the applicability and capability of the presented method..
4. Xinyan Peng, Guangqi Chen, Pengcheng Yu, Yingbin Zhang, Jinmei Wang, Improvement of joint definition and determination in three-dimensional discontinuous deformation analysis, Computers and Geotechnics, 10.1016/j.compgeo.2019.02.016, 110, 148-160, 2019.06, Joint property in three-dimensional discontinuous deformation analysis (3-D DDA) is crucial. The joint property in a contact relies upon just one of the contacting objects in original 3-D DDA, which is not always sufficiently accurate and can even yield unreasonable results. To overcome the limitations in original 3-D DDA, an improved joint definition and determination method that simultaneously considers the joint properties of both connected objects for contacts is proposed, which permits the applied joint parameters to change in the simulation. Several numerical examples are evaluated to demonstrate the advantage and applicability of the proposed method. The simulation results computed by the improved 3-D DDA accord well with the analytical expectations and physical reality, while the original 3-D DDA shows unphysical results. The improved 3-D DDA can provide more reliable information in rockslide disaster prevention and mitigation because joint parameters in a contact can be chosen appropriately in real time during simulations. Therefore, the improved 3-D DDA is more applicable and accurate, which can be further extended to more generalized theoretical and engineering problems..
5. Yan jun Zhang, Ting kai Nian, Xing sen Guo, Guangqi Chen, Lu Zheng, Modelling the flexural buckling failure of stratified rock slopes based on the multilayer beam model, Journal of Mountain Science, 10.1007/s11629-018-5007-1, 16, 5, 1170-1183, 2019.05, The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized Hoek-Brown failure criterion is introduced to reflect the influences of slope size (scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle..
6. Zheng Han, Bin Su, Yange Li, Wei Wang, Weidong Wang, Jianling Huang, Guangqi Chen, Numerical simulation of debris-flow behavior based on the SPH method incorporating the Herschel-Bulkley-Papanastasiou rheology model, Engineering Geology, 10.1016/j.enggeo.2019.04.013, 255, 26-36, 2019.05, A rational rheology model is critical for the numerical simulation of debris-flow behavior. The Bingham model commonly used in many current studies has failed to simulate the shear thickening and thinning phenomenon in experiments. We report an alternative solution by incorporating the Herschel-Bulkley-Papanastasiou (HBP) model with the smoothed particle hydrodynamic (SPH) method. The SPH simulation is based on the open-source DualSPHysics scheme, upon which we built a development by the Bingham-based rheology model in our previous study. In this paper, a straightforward improvement is made such that the HBP model is incorporated to describe the constitutive law between particles, extending the compatibility of the simulation to dilatant and pseudoplastic fluids. To illustrate the performance of the HBP-based SPH method, first, a sensitivity analysis was performed to investigate the influence of important rheological coefficients. The proposed method was then verified by a dam-break experiment of water-clay mixtures and the case study of the 2010 Yohutagawa debris-flow event in Japan. The results indicate a good accordance between simulation and observation. A discussion regarding the potential and limitations of the current method concludes the paper..
7. Wei Wang, Kunlong Yin, Guangqi Chen, Bo Chai, Zheng Han, Jiawen Zhou, Practical application of the coupled DDA-SPH method in dynamic modeling for the formation of landslide dam, Landslides, 10.1007/s10346-019-01143-5, 16, 5, 1021-1032, 2019.05, Landslides along river margins can cause permanent or temporal landslide dams and dammed-lakes, threatening people’s life and properties. Investigation of the formation process for the landslide dam is crucial for emergency response and mitigation planning. However, the formation process modeling for a practical case usually involves large scale and complicates geometry. To overcome the computation complexity and promote efficiency, a series of practical techniques have been proposed. Firstly, an Open Channel Model with Steady Flow (OCMSF) has been developed to naturally produce a river flow. Then, a three-stage simulation strategy has been proposed to fulfill the large-scale practical modeling. In specific, stage 1 generated a steady open channel flow using SPH method. In stage 2, the DDA method is used to simulate landslide movement until the mass reaches the river. In stage 3, the formation process with landslide-river interaction is realized using a coupled DDA-SPH method. The formation process of the Yangjiagou landslide dam was selected as the practical application. Simulation results showed the Yangjiagou landslide reached the river with a front velocity of 22 m/s in around 8 s and formed a dam with estimated volume of 500,000 m
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, which is consistent with the site investigation. It is thus demonstrated the applicability and performance of the coupled method and numerical techniques in modeling practical landslide dam case..
8. Longxiao Guo, Tonglu Li, Guangqi Chen, Pengcheng Yu, Xinyan Peng, Deguang Yang, A method for microscopic unsaturated soil-water interaction analysis based on DDA, Computers and Geotechnics, 10.1016/j.compgeo.2018.12.002, 108, 143-151, 2019.04, Unsaturated soil is a three-phase discontinues system, and microscopic analysis can provide an intrinsic understanding for macroscopic mechanical behavior of the soil. Discontinuous Deformation Analysis (DDA) has the advantage for analyzing the material like granular aggregates. Based on capillary mechanics, a newly developed algorithm is applied in conventional DDA code, which treats a DDA element as an ideal soil particle and exerts capillary force among elements. Then, to validate the extended method, an ideal microscopic soil model is established, and the simulation results are in good agreement with typical analytical solutions. It indicates that the developed DDA is reliable and applicable to explore unsaturated soil behaviors microscopically..
9. Xinyan Peng, Guangqi Chen, Pengcheng Yu, Yingbin Zhang, Longxiao Guo, Cungen Wang, Xiao Cheng, Hui Niu, Parallel computing of three-dimensional discontinuous deformation analysis based on OpenMP, Computers and Geotechnics, 10.1016/j.compgeo.2018.11.016, 106, 304-313, 2019.02, The computing efficiency of three-dimensional discontinuous deformation analysis (3D-DDA) needs to be improved for large-scale simulations. Among all the subroutines of 3D-DDA, the equation solver is very time-consuming. To accelerate the equation-solving process, this paper proposes implementing the parallel block Jacobi (BJ) and preconditioned conjugate gradient (PCG) iterative solvers into the original 3D-DDA based on OpenMP. The calculation accuracy and computational efficiency are studied by several numerical examples, demonstrating that the modified 3D-DDA with parallel BJ or PCG solver exhibits much higher execution efficiency with satisfactory correctness. The maximum speedup ratio is up to 5.1 for the cases studied..
10. Xinyan Peng, Pengcheng Yu, Guangqi Chen, Mingyao Xia, Yingbin Zhang, Development of a Coupled DDA–SPH Method and its Application to Dynamic Simulation of Landslides Involving Solid–Fluid Interaction, Rock Mechanics and Rock Engineering, 10.1007/s00603-019-01900-x, 2019.01, Landslides involving solid–fluid interaction such as submarine landslides and landslide dams occur frequently around the world, which may bring severe damage to human lives and properties. Investigation of such landslides is thus of significance to hazard prevention and mitigation. To conduct the analysis, there are three key points to be addressed: (a) the landslide failure process, (b) the free surface flow, and (c) the solid–fluid interaction process. Discontinuous deformation analysis (DDA) method is suitable for analyzing discontinuous blocky systems and has outstanding advantages in simulating the landslide failure process. Meanwhile, smoothed particle hydrodynamics (SPH) method is well-suited for modeling the free surface flow. However, the consideration of solid–fluid interaction in these two methods is seldom, which somehow restricts their applications. With the aim to take advantages of these two methods, a coupled DDA–SPH method in two-dimensional case is proposed, in which the solid–fluid interaction is forced using a penalty approach. The SPH formulations are implemented into DDA code. Several numerical examples are presented to check the validity of the proposed method. A dam-break test is first investigated to show the success of implementing SPH into DDA code for modeling the fluid flow in later simulations of fluid–solid systems. Subsequently, the performance of the coupled DDA–SPH method is validated through a submarine rigid landslide, and the simulation results are in good agreement with the experimental data. Further, an extension study on the submarine deformable landslide is performed, in which the landslide mass consists of multiple blocks and a sensitivity analysis on the interface friction angle between blocks is conducted. Finally, a designed landslide dam is simulated to show the applicability and feasibility of the coupled DDA–SPH method..
11. Pengcheng Yu, Yingbin Zhang, Xinyan Peng, Guangqi Chen, John X. Zhao, Distributed-Spring Edge-to-Edge Contact Model for Two-Dimensional Discontinuous Deformation Analysis, Rock Mechanics and Rock Engineering, 10.1007/s00603-019-01917-2, 2019.01, Edge-to-edge contact is a fundamental contact type in blocky systems. In two-dimensional discontinuous deformation analysis (2D DDA, and hereinafter DDA for short), an edge-to-edge contact is transformed into two separated vertex-to-edge contacts by applying two pairs of concentrated springs. Although this simplification facilitates the DDA algorithm, it is not always sufficiently accurate and can even yield irregular results. To solve this problem, a distributed-spring contact model (DSCM) that exerts distributed instead of concentrated forces on contact edges is proposed in this paper for the edge-to-edge contact in DDA. Submatrices for the force matrix and stiffness matrix are obtained by minimizing the potential energy of the distributed contact forces and are incorporated into an improved DDA (I-DDA) code. Four examples are evaluated to illustrate the validations and advantages of the I-DDA. The first example is a single square impacting on a base block. Deformation of the contact area is evaluated by comparison with the theoretical deformation solution, and the results calculated by the I-DDA show better agreement with the analytical solution than the original DDA (O-DDA). The second example is an impact validation, proving that the I-DDA is more adaptable to discrete systems containing blocks of different sizes. Then an example and an experiment about block rebounding are provided, demonstrating that the errors in rotation and rebounding exhibited in the O-DDA results are avoided when using the I-DDA, indicating that the I-DDA provides more realistic solutions. The results of this study suggest that the proposed I-DDA incorporating the DSCM is quite accurate and capable of improving calculation accuracy compared to the O-DDA..
12. Yingbin Zhang, Jinmei Wang, John X. Zhao, Guangqi Chen, Pengcheng Yu, Tao Yang, Multi-spring Edge-to-Edge Contact Model for Discontinuous Deformation Analysis and Its Application to the Tensile Failure Behavior of Rock Joints, Rock Mechanics and Rock Engineering, 10.1007/s00603-019-01973-8, 2019.01, Edge-to-edge is the most common form of contact in a two-dimensional joint block system. Discontinuous deformation analysis (DDA) is a powerful tool for handling block systems and treats an edge-to-edge contact as two vertex-to-edge contacts with a couple of normal and shear springs at the extremes of the contact segment. However, this method is unsuitable for evaluating the tensile failure of a joint under asymmetrical tension conditions, even though it can simplify the contact type and increase computational efficiency. This is mainly because the distributed forces at an edge-to-edge contact are simplified as two couples of concentrated forces. To solve this problem, this paper proposes incorporating a multi-spring edge-to-edge contact model with DDA. In the model, several contact pairs with normal and shear springs on an edge-to-edge contact are set to simulate the distributed forces. Several benchmark tests were performed to demonstrate the discrepancy between the original and improved DDAs. The results revealed that the latter more accurately models the stress distribution across the edge-to-edge contact, providing a more reasonable acceleration required to topple a series of blocks resting on an inclined stepped base..
13. Zheng Han, Yange Li, Yinfei Du, Weidong Wang, Guangqi Chen, Noncontact detection of earthquake-induced landslides by an enhanced image binarization method incorporating with Monte-Carlo simulation, Geomatics, Natural Hazards and Risk, 10.1080/19475705.2018.1520745, 10, 1, 219-241, 2019.01, Detecting landslides using remote sensing images involves converting gray level images into binary images. Given the complex background and non-uniform illumination in the regional remote sensing image, the commonly-used global thresholding methods are limited to interpret some landslides those hidden in the shadow. In this paper, we report on an enhanced image thresholding method for the noncontact detection of earthquake-induced landslides. The proposed method incorporates Monte-Carlo simulation into the local thresholding method, and essential issues, regarding complex illumination condition and uncertainties of determining block size in local thresholding method, are addressed. To better separate landslide candidate objects from the background, we incorporate Digital Surface Model (DSM) into the binary image, such that the interferences by built-up areas, terraces, and rivers can be significantly reduced considering the indicator of slope gradient. The described method has been tested using two benchmark tests, showing that the proposed method performs well dealing with the complex background and illumination condition. As a case study, we use the proposed method to detect landslides in a remote sensing image near Beichuan area after the 2008 Ms8.0 Wenchuan earthquake. Results demonstrate that the presented method interprets landslides resembling those of manually visual delineation..
14. Xinyan Peng, Pengcheng Yu, Yingbin Zhang, Guangqi Chen, Applying modified discontinuous deformation analysis to assess the dynamic response of sites containing discontinuities, Engineering Geology, 10.1016/j.enggeo.2018.10.011, 246, 349-360, 2018.11, The accurate consideration of seismic wave propagation through discontinuous media is crucial in rock engineering. Discontinuous deformation analysis (DDA), with the ability to study discontinuity behaviors, is modified by incorporating a seismic input method based on a viscous boundary and the free-field theory. After confirming the accuracy of the modified DDA using several verification examples, two practical applications, (1) the extreme ground motion during the 2008 Iwate–Miyagi earthquake, Japan, and (2) the Donghekou landslide induced by the 2008 Wenchuan earthquake, China, are simulated and reproduced by the modified DDA. The results show that seismic wave propagation through discontinuous media can be accurately simulated by the modified DDA. Further, the simulation results indicate that discontinuities are critical in the dynamic response of structures. Conclusively, the modified DDA provides an alternative approach for analyzing the dynamic response of sites containing discontinuities..
15. Zhujun Li, Shuguang Liu, Hong Zhang, Guangqi Chen, Wei Wu, Hehua Zhu, Xiaoying Zhuang, Wei Wang, Simulating the damage extent of unreinforced brick masonry buildings under boulder impact using three-dimensional discontinuous deformation analysis (3-D DDA), Engineering Failure Analysis, 10.1016/j.engfailanal.2018.07.013, 93, 122-143, 2018.11, The main material of brick masonry buildings is discontinuous masonry material. This study presents a critical review of the damage characteristics of masonry and the methods for studying the behavior of masonry. The damage extent of brick masonry buildings under boulder impact is analyzed using an approach based on three-dimensional discontinuous deformation analysis (3-D DDA). A “block-joint” model is established to represent the brick and mortar of the building, which is based on the discontinuous characteristics of the masonry material. On this basis, a benchmark model is used to validate the 3-D DDA. Using this approach, the velocity distribution and several displacements of key points of the building blocks are obtained to compare the damage extent of the building under six different cases that consider in-plane or out-of-plane boulder impacts to the building at different heights. The size and material parameters of the building model are based on the most common buildings in the field of investigation. These results can be used to show the failure process of buildings on a continuous basis or to quantitatively compare the damage extent of different types of buildings. By analyzing the force condition of the basic element blocks, the results demonstrate that the damage extent of the building is related to the impact direction, impact height, location relationship between the damaged part and the impact position, and constraint condition..
16. Hong Zhang, Shu guang Liu, Wei Wang, Lu Zheng, Ying bin Zhang, Yan qiang Wu, Zheng Han, Yan ge Li, Guangqi Chen, A new DDA model for kinematic analyses of rockslides on complex 3-D terrain, Bulletin of Engineering Geology and the Environment, 10.1007/s10064-016-0971-6, 77, 2, 555-571, 2018.05, Landslides are common phenomena in mountainous regions worldwide. Over the past two decades, catastrophic rockslides in mountainous regions have caused serious damage and fatalities. To develop effective preventive countermeasures, it is important to estimate the kinematic behavior of displaced masses after slope failures, such as the velocity, run-out distance, and extent. Discontinuous deformation analysis (DDA) is an appropriate tool to analyze the dynamics, kinematics, and deformability of a block assembly. Many studies have reported applications of DDA to kinematic analyses of rockslides on two-dimensional (2-D) terrain. However, because of the restrictions of numerical techniques, few kinematic analyses of rockslides on three-dimensional (3-D) terrain have been performed using DDA. This study developed a new DDA model for the analysis of rockslides on 3-D terrain. First, contact treatment techniques for the 3-D model were developed to create an accurate and efficient computational scheme. The new model was then verified by the benchmark tests on the four basic types of block motion on 3-D terrain. Finally, the new model was applied to a designed rockslide with complex terrain to demonstrate its practical applicability. The results indicate that the new 3-D DDA model is an effective tool to analyze 3-D rockslides and could potentially be used to optimize protection designs for rockslides..
17. G. Samodra, Guangqi Chen, J. Sartohadi, Kiyonobu Kasama, Generating landslide inventory by participatory mapping
an example in Purwosari Area, Yogyakarta, Java, Geomorphology, 10.1016/j.geomorph.2015.07.035, 306, 306-313, 2018.04, This paper proposes an approach for landslide inventory mapping considering actual conditions in Indonesia. No satisfactory landslide database exists. What exists is inadequate, focusing, on data response, rather than on pre-disaster preparedness and planning. The humid tropical climate also leads a rapid vegetation growth so past landslides signatures are covered by vegetation or dismantled by erosion process. Generating landslide inventory using standard techniques still seems difficult. A catalog of disasters from local government (village level) was used as a basis of participatory landslide inventory mapping. Eyewitnesses or landslide disaster victims were asked to participate in the reconstruction of past landslides. Field investigation focusing on active participation from communities with the use of an innovative technology was used to verify the landslide events recorded in the disaster catalog. Statistical analysis was also used to obtain the necessary relationships between geometric measurements, including the height of the slope and length of run out, area and volume of displaced materials, the probability distributions of landslide area and volume, and mobilization rate. The result shows that run out distance is proportional to the height of the slope. The frequency distribution calculated by using non-cumulative distribution empirically exhibits a power law (fractal statistic) even though rollover can also be found in the dataset. This cannot be the result of the censoring effect or incompleteness of the data because the landslide inventory dataset can be classified as having complete data or nearly complete data. The so-called participatory landslide inventory mapping method is expected to solve the difficulties of landslide inventory mapping and can be applied to support pre-disaster planning and preparedness action to reduce the landslide disaster risk in Indonesia. It may also supplement the usually incomplete data in a typical landslide inventory..
18. Guangqi Chen, Manchao He, Fusong Fan, Rock burst analysis using DDA numerical simulation, International Journal of Geomechanics, 10.1061/(ASCE)GM.1943-5622.0001055, 18, 3, 2018.03, A rock burst can cause a serious disaster. For the mitigation of rock burst-induced disaster, the possibility assessment of a rock burst for an underground excavation is a key undertaking and also a great challenge because rock burst failure involves a dynamic and large deformation process. In this paper, a numerical simulation method of rock burst using discontinuous deformation analysis (DDA) is proposed by showing the advantage of DDA in handling the large deformation of this dynamic process. First, the problem of using the number of the adjacent boundary in the original algorithm of the DDA program was determined and solved, which is critical and important in analyzing artificial mesh models. The DDA model was used for simulating a rock burst process and was verified by a true triaxial test in which the critical stress for rock burst had been clarified. Then, the effects of rock hardness and brittleness on critical stresses were clarified quantitatively. The critical stresses of a rock burst were estimated for rocks with various values of the elastic modulus, Poisson's ratio, cohesion, friction angle, and tension strength. Finally, a strategy is proposed for examining the critical depth of a rock burst for various types of rocks under different tectonic levels. Rocks are classified by the mechanical properties of them, such as elastic modulus, Poisson's ratio, cohesion, friction angle, and tensile strength. The depth condition was converted to initial stress. The tectonic condition was represented by the ratio of horizontal-to-vertical components of the initial stress. Through a large set of simulations, the critical depths of rock bursts in seven types of rocks were estimated for different tectonic levels. The results show that the proposed rock burst analysis using DDA simulation is effective and useful..
19. Zheng Han, Weidong Wang, Yange Li, Jianling Huang, Bin Su, Chuan Tang, Guangqi Chen, Xia Qu, An integrated method for rapid estimation of the valley incision by debris flows, Engineering Geology, 10.1016/j.enggeo.2017.11.007, 232, 34-45, 2018.01, Valley incision by debris flow is an important process in creating and maintaining the topography of a valley, in addition to explaining the significant growth of the magnitudes of debris flow hazards. In this paper, we introduce a semi-empirical method to quantitatively estimate the valley incision process by debris flows over complex bed surface. We first reproduce natural bed surface across the valley by a polyline, and use a hydrograph of discharge versus time to represent the temporal variation of debris flow process. The presented method subsequently predicts the debris flow behavior over an irregular bed surface. A dynamic erosion law considers the solved debris flow behavior and estimates an instantaneous erosion rate. Finally, the accumulative incision depth of bed sediment is calculated, reshaping the initial bed surface across the valley. The presented method is simple and therefore notably beneficial for practical work. The performance of the proposed method has been tested using two case study applications. Results demonstrate that the presented method estimates comparable incision depth as revealed in the in-situ survey and the numerical simulation..
20. A. Q. Akbar, Guangqi Chen, Comparison of major statistical methods and their combination using matrix validation for landslide susceptibility mapping, lowland technology international, 20, 3, 401-412, 2018.01, Landslide risk exists with the mountain regions and every year creates a great life and financial losses. To prevent the disaster, numbers of statistical methods have been proposed, but it is still unclear which one is more accurate and yet very few studies proposes a reliable method. Therefore, this study aims to compare the commonly used bivariate statistical method and multivariate statistical methods and their combination to achieve higher accuracy for landslide susceptibility map. Moreover, the classification used for landslide susceptibility mapping is associated with errors, which affects the accuracy of the analysis. In this study, new tool was designed to reduce the classification. To implement this study, a landslide susceptibility maps were created Kabul city. The result proposes that the new designed tool is a good way not only to reduce the classification error by defining the critical thresholds for the classifications. Moreover, all of the statistical methodologies is giving and acceptable result but the combination bivariate and multivariate statistical methods increase the accuracy of the analysis and they are complimentary to each other..
21. Fei Qiu, Jianling Huang, Yange Li, Zheng Han, Weidong Wang, Guangqi Chen, Xia Qu, Bin Su, Protecting highway bridges against debris flows using lateral berms
A case study of the 2008 and 2011 Cheyang debris flow events, China, Geomatics, Natural Hazards and Risk, 10.1080/19475705.2017.1414718, 9, 1, 196-210, 2017.12, Lateral berms are often constructed to protect highway bridges against debris flows in mountainous regions. Currently, different solutions for lateral berm design are debated. The lack of standardization results in the improper design of lateral berms, limiting the mitigating effect. In this paper, a monitoring case of the mitigating effect of a lateral berm is introduced. The lateral berm was constructed through a bridge culvert at the alluvial fan of a debris-flow gully. In September 2008, a debris flow in this gully completely buried the lateral berm. The proposed numerical integral method was used to back analyse the flowing velocity and mud depth in berm. Results supported the speculation that abrupt decreases in mud depth and flow velocity in the lateral berm caused deposits that compressed the effective berm depth and resulted in overtopping flow. Therefore, we suggested reducing the berm width in order to increase the flow velocity in the berm. In June 2011, another debris flow with a smaller magnitude occurred in the gully, and the reconstructed lateral berm reportedly performed well to protect the bridge of Yalu highway. The case studies highlighted that berm width should be one of the main considerations in the berm design..
22. Han Z., Li Y.G., Huang J.L., Chen G.Q., Xu L.R., Numerical simulation for run-out extent of debris flows using improved Cellular Automaton model. Bulletin of engineering geology and environments, Bulletin of Engineering Geology and the Environment, 10.1007/s10064-016-0902-6, 76, 3, 961-974, 2017.08, Numerical simulation of the debris-flow process is commonly based on the shallow water equations. However, as a two-phase anisotropic mixture, debris flows display complex rheological behavior, making it difficult to model or to simulate these using standard approaches. In this paper, an improved cellular automaton (CA) model is developed for simulating the extent of debris-flow run-out. The CA model consists of three essential components: cellular space, lattice relation, and transition function. A two-dimensional rectangular cellular space is generated from mesh grid in the digital terrain model data, and the Moore neighborhood type is selected as the lattice relation. We also use a transition function based on a Monte Carlo iteration algorithm to automatically search the flow direction and flow routine. Specifically, this new transition function combines the topography function and persistence function (due to the flow inertia), and is advanced in its ability to avoid certain illogical lateral spreading due to abrupt changes in topography. In addition, in contrast to previous studies, in the present work, we regressed the persistence function from a well-documented flume experiment, rather than using a manipulated constant value as described in earlier empirical studies. Our results show that the debris-flow persistence function is closely related to the channel slope. It approximates the law of cosines at a steep slope and Gamma law at a gentle slope. To illustrate the performance of the improved CA model, we selected the 2010 Yohutagawa debris-flow event in Japan as a case study. Our results show that the simulated deposition perimeter pattern and run-out distance are in high accordance with the data from in situ investigation..
23. Wei Wang, Guangqi Chen, Yingbin Zhang, Lu Zheng, Hong Zhang, Dynamic simulation of landslide dam behavior considering kinematic characteristics using a coupled DDA-SPH method, Engineering Analysis with Boundary Elements, 10.1016/j.enganabound.2017.02.016, 80, 172-183, 2017.07, Landslide with significant volume and considerable velocity may block the river stream in the hillslope-channel coupling system, forming the natural dam and the dammed-lake behind. Previous studies predicted the behavior of landslide dams using different dimensionless indexes derived from the geomorphological characteristics. However, the kinematic characteristics of the river and landslide also play key roles in the dam formation. To consider the kinematic characteristics, the dynamic simulation of the dam behavior (formation and failure) involves three problems: (i) the movement of the river flow, (ii) the landslide movement and (iii) the landslide-river interaction. In this study, the movement of the river flow is simulated by a particle recycling method (PRM) under the framework of smoothed particle hydrodynamics (SPH). The discontinuous deformation analysis (DDA) is used to model the landslide movement. The interaction between the solid and fluid phases is achieved by the coupled DDA-SPH method. The proposed methods have been implemented in the numerical code, and a series of examples were employed for validations. The importance of the kinematic characteristics for the dam behavior was demonstrated by a series of numerical scenarios..
24. Yanqiang Wu, Guangqi Chen, Zaisen Jiang, Long Zhang, Hong Zhang, Fusong Fan, Zheng Han, Zhenyu Zou, Liu Chang, Layue Li, Research on fault cutting algorithm of the three-dimensional numerical manifold method, International Journal of Geomechanics, 10.1061/(ASCE)GM.1943-5622.0000655, 17, 5, 2017.05, The fault cutting algorithm is important when applying the three-dimensional numerical manifold method to engineering simulation. This paper presents a primary approach to the fault cutting algorithm, including data structures, fault cutting procedures, and some basic computing algorithms. First, the data structures of the physical elements and mathematical covers are proposed as single linked lists and linked list arrays, respectively. This reduces the complexity of the algorithm and increases the efficiency when connecting physical elements to covers. Second, a strategy of recording cutting traces between every two faults to ensure that the model agrees with the actual situation was proposed. This strategy also reduces the complexity and improves the efficiency. Third, the mathematical covers and physical elements are cut with all faults independently to process complete cutting instances in a multiblock form and incomplete cutting instances without forming any new irrational block. Finally, four cutting examples are presented that demonstrate that the proposed fault cutting algorithm is correct and useful..
25. Guruh Samodra, Guangqi Chen, Junun Sartohadi, Kiyonobu Kasama, Comparing data-driven landslide susceptibility models based on participatory landslide inventory mapping in Purwosari area, Yogyakarta, Java, Environmental Earth Sciences, 10.1007/s12665-017-6475-2, 76, 4, 2017.02, There are different approaches and techniques for landslide susceptibility mapping. However, no agreement has been reached in both the procedure and the use of specific controlling factors employed in the landslide susceptibility mapping. Each model has its own assumption, and the result may differ from place to place. Different landslide controlling factors and the completeness of landslide inventory may also affect the different result. Incomplete landslide inventory may produce significance error in the interpretation of the relationship between landslide and controlling factor. Comparing landslide susceptibility models using complete inventory is essential in order to identify the most realistic landslide susceptibility approach applied typically in the tropical region Indonesia. Purwosari area, Java, which has total 182 landslides occurred from 1979 to 2011, was selected as study area to evaluate three data-driven landslide susceptibility models, i.e., weight of evidence, logistic regression, and artificial neural network. Landslide in the study area is usually affected by rainfall and anthropogenic activities. The landslide typology consists of shallow translational and rotational slide. The elevation, slope, aspect, plan curvature, profile curvature, stream power index, topographic wetness index, distance to river, land use, and distance to road were selected as landslide controlling factors for the analysis. Considering the accuracy and the precision evaluations, the weight of evidence represents considerably the most realistic prediction capacities (79%) when comparing with the logistic regression (72%) and artificial neural network (71%). The linear model shows more powerful result than the nonlinear models because it fits to the area where complete landslide inventory is available, the landscape is not varied, and the occurence of landslide is evenly distributed to the class of controlling factor..
26. Guangqi Chen, Tsukasa Kawakami, Yingbin Zhang, Mechanism analysis of earthquake induced extreme motions
Clarifying extreme acceleration, 51st US Rock Mechanics / Geomechanics Symposium 2017 51st US Rock Mechanics / Geomechanics Symposium 2017, 4, 2905-2910, 2017.01, Earthquake induced extreme motions are classified as the extreme large acceleration, the extreme large velocity and the extreme large displacement. In this paper, a sudden braking model is proposed for the mechanism of the extreme large acceleration, i.e. The extreme large acceleration can easily occur when a moving body is suddenly braked. The model is verified by theoretical analysis, laboratory experiments and numerical simulation using DDA. It is successful to reproduce the unprecedented vertical surface acceleration of nearly four times gravity, recorded at the West Ichinoseki station during the 14 June 2008 Iwate-Miyagi earthquake (Ms6.9) in Japan, by DDA simulation..
27. Yingbin Zhang, John X. Zhao, Xiaofu Huang, Guangqi Chen, Tomohiro Hamasaki, Shaking table test for estimating the effects of seismic loading on the mobility of rockfall, 51st US Rock Mechanics / Geomechanics Symposium 2017 51st US Rock Mechanics / Geomechanics Symposium 2017, 4, 2890-2894, 2017.01, Rockfall is one of the most frequent geo-hazards, which often occurs in mountain areas and along land transportation. It often causes serious consequences in terms of lives lost, homes destroyed and infrastructures disrupted because its high energy and significant mobility, although it usually impacts only small areas compared to other geo-hazards. Rockfall could be activated by various triggers, in which earthquake is one important trigger. Estimate the run-out of earthquake-induced rockfall is important for choosing suitable protection measures. A growing body of evidence, including site videos and eyewitness testimonies, suggests that the ground still intensively quake when the process of rockfall. The main purpose of this paper is to clarify whether the seismic loading has any influence on the mobility of rockfall through shaking table test. Thousands of tests are conducted to investigate the effects of the amplitude and the frequency of simple harmonic seismic loading on the horizontal and the lateral displacements of triangular prism, quadrangular prism, pentagonal prism and hexagonal prism. The results show the significant effects of seismic loading on the run-out distance and the lateral displacements of rockfall..
28. Long Zhang, Guangqi Chen, Yanqiang Wu, Han Jiang, Stochastic ground-motion simulations for the 2016 Kumamoto, Japan, earthquake 2016 Kumamoto earthquake sequence and its impact on earthquake science and hazard assessment 4. Seismology, Earth, Planets and Space, 10.1186/s40623-016-0565-3, 68, 1, 2016.12, On April 15, 2016, Kumamoto, Japan, was struck by a large earthquake sequence, leading to severe casualty and building damage. The stochastic finite-fault method based on a dynamic corner frequency has been applied to perform ground-motion simulations for the 2016 Kumamoto earthquake. There are 53 high-quality KiK-net stations available in the Kyushu region, and we employed records from all stations to determine region-specific source, path and site parameters. The calculated S-wave attenuation for the Kyushu region beneath the volcanic and non-volcanic areas can be expressed in the form of Q s = (85.5 ± 1.5)f 0.68±0.01 and Q s = (120 ± 5)f 0.64±0.05, respectively. The effects of lateral S-wave velocity and attenuation heterogeneities on the ground-motion simulations were investigated. Site amplifications were estimated using the corrected cross-spectral ratios technique. Zero-distance kappa filter was obtained to be the value of 0.0514 ± 0.0055 s, using the spectral decay method. The stress drop of the mainshock based on the USGS slip model was estimated optimally to have a value of 64 bars. Our finite-fault model with optimized parameters was validated through the good agreement of observations and simulations at all stations. The attenuation characteristics of the simulated peak ground accelerations were also successfully captured by the ground-motion prediction equations. Finally, the ground motions at two destructively damaged regions, Kumamoto Castle and Minami Aso village, were simulated. We conclude that the stochastic finite-fault method with well-determined parameters can reproduce the ground-motion characteristics of the 2016 Kumamoto earthquake in both the time and frequency domains. This work is necessary for seismic hazard assessment and mitigation..
29. Guruh Samodra, Guangqi Chen, Junun Sartohadi, Danang Sri Hadmoko, Kiyonobu Kasama, Muhammad Anggri Setiawan, Rockfall susceptibility zoning based on back analysis of rockfall deposit inventory in Gunung Kelir, Java, Landslides, 10.1007/s10346-016-0713-7, 13, 4, 805-819, 2016.08, A rockfall susceptibility based on trajectory-energy/velocity approach needs release area or rockfall source. However, identification of rockfall source is not always possible for some areas in Indonesia. This paper presents a rockfall susceptibility zoning based on back analysis technique of rockfall deposit inventory in Gunung Kelir, Java. There were several steps in the rockfall susceptibility zoning: (1) rockfall deposit inventory, (2) rockfall simulation based on back analysis of rockfall deposit inventory, (3) sensitivity analysis, and (4) rockfall susceptibility zoning. The result suggests that the travel distance is affected by the spatial distribution of rockfall source, lithology or surface material, and topography (angle of slope and angle of aspect). Final trajectories were employed to generate landslide susceptibility map which may allow a policy maker to have an advanced consideration to achieve specified risk measures and evaluation of their cost efficiency to optimize budget and design. Application of rockfall susceptibility zoning based on back analysis of rockfall deposits is efficient where rockfall source information is unavailable..
30. Hong Zhang, Shu guang Liu, Guangqi Chen, Lu Zheng, Ying bin Zhang, Yan qiang Wu, Pei deng Jing, Wei Wang, Zheng Han, Gui hui Zhong, Sha Lou, Extension of three-dimensional discontinuous deformation analysis to frictional-cohesive materials, International Journal of Rock Mechanics and Mining Sciences, 10.1016/j.ijrmms.2016.03.021, 86, 65-79, 2016.07, This paper extends three-dimensional discontinuous deformation analysis (3-D DDA) to model the frictional-cohesive failure behavior of geotechnical materials and structures. Firstly, a new contact detection scheme was developed to successfully identify the dominant sub-contacts and areas of the joints between arbitrarily shaped polyhedral blocks. Secondly, a modified joint contact model subjected to the Mohr-Coulomb failure criteria based on distributed cohesion instead of concentrated cohesion, was proposed to ensure the accuracy of the simulation by 3-D DDA. Thirdly, the extended 3-D DDA was verified by three examples, including joint contact detection, critical stability and failure mode of a system of polyhedral blocks. Finally, the complete failure process involving large displacement and rotation of multiple interaction blocks is exhibited dynamically. Overall, these examples exhibit that the extended 3-D DDA is now capable of accurately modeling the failure behavior of frictional-cohesive materials and structures, so as to optimize the material and structure stabilization or protection design..
31. GUANGQI CHEN, Fusong FAN, Stability analysis of toppling slope using the extended NMM , American Rock Mechanics Association , 6ページ, 2016.06, The original numerical manifold method (NMM) is extended for stability analysis of a toppling slope with complex sliding surface and cohesion and tensile strengths existing in discontinuities. The extended NMM is shown effective by reproducing a centrifuge test. With NMM simulation, the commonly used Goodman and Bray’s analytical method is shown adaptable to a toppling slope model with a simple sliding surface without cohesion and tensile strengths in the discontinuities. It is shown that the deformation of the sliding body has no significant effect on the result. The relationship between dip angle and critical friction angle is investigated. A real toppling slope is simulated and the necessary cohesion and friction angle are verified. .
32. Suhua ZHOU, GUANGQI CHEN, Distribution Pattern of Landslides Triggered by the 2014 Ludian Earthquake of China: Implications for Regional Threshold Topography and the Seismogenic Fault Identification, ISPRS International Journal of Geo-Information , doi:10.3390/ijgi5040046, 22ページ, 2016.05.
33. Wei Wang, GUANGQI CHEN, 3D numerical simulation of debris-flow motion using SPH method incorporating non-Newtonian fluid behavior, Natural Hazards, 81, 3, 2016.04, Flow-type landslide, such as debris-flow, often exhibits high velocity and long run-out distance. Simulation on it benefits the propagation analysis and provides solution for risk assessment and mitigation design. Previous studies commonly used shallow water assumption to simulate this phenomenon, ignoring the information in vertical direction, and the Bingham model to describe constitutive law of non-Newtonian fluid can cause numerical divergence unless necessary parameter is defined. To address the issue, the full Navier–Stokes equations are adopted to describe the dynamics of the flow-type landslides. Additionally, the general Cross model is employed as the constitutive model, which ensures the numerical convergence. Rheological parameters are introduced from the Bingham model and the Mohr–Coulomb yield criterion. Subsequently, the governing equations incorporating the modified rheological model are numerically built in the smoothed particle hydrodynamics (SPH) framework and implemented into the open-source DualSPHysics code. To illustrate its performance, the 2010 Yohutagawa debris-flow event in Japan is selected as a case study. Parameters regarding the debris magnitude, i.e., the front velocity and section discharge, were also well analyzed. Simulated mass volume and deposition depth at the alluvial fan are in good agreements with the in situ observation. On the basis of the results, the developed method performs well to reproduce the debris-flow process and also benefits the analysis of flow characteristics, affected area for risk assessment and mitigation design..
34. Wei Wang, GUANGQI CHEN, Analysis of landslide-generated impulsive waves using a coupled DDA-SPH method, Engineering Analysis with Boundary Elements, 64, 2016.04, Large impulsive waves generated by slope failures and a subsequent landslide in a reservoir area may lead to serious damage to the dam, shoreline properties and lives. Therefore, analysis of landslide-generated impulsive waves is of significant importance for hazard prevention and reduction. There are three key points for analyzing this problem: (i) the landslide run-out, (ii) the free surface flow and (iii) the landslide-water interaction process. The Discontinuous Deformation Analysis (DDA) method was previously developed to investigate discontinuous block movements, while the Smoothed Particle Hydrodynamics (SPH) method was used mostly to model free surface flow. However, the solid–fluid interaction is seldom considered in the respective fields, which greatly restricts their applications. For this reason, the coupled DDA-SPH method was proposed in this study to solve the solid–fluid interaction problem. To validate this approach, this study considered a wedge sliding along an inclined plane and interacting with the water body. The corresponding Heinrich’s experimental results were adopted to evaluate the accuracy of the coupled method in modeling the landslide movement and wave profile, proving that the landslide motion and wave profiles could be captured accurately by the coupled method. Finally, the effect of the governing parameters on the wave amplitude was discussed.
35. Wei Wang, GUANGQI CHEN, Modeling of landslide generated impulsive waves considering complex topography in reservoir area, Environmental Earth Sciences, 75, 2016.04.
36. Suhua ZHOU, GUANGQI CHEN, GIS-Based Integration of Subjective and Objective Weighting Methods for Regional Landslides Susceptibility Mapping, Sustainability, Vol. 8, No.4, 2016.04.
37. Suhua ZHOU, GUANGQI CHEN, A Combined Weight of Evidence and Logistic Regression Method for Susceptibility Mapping of Earthquake-induced Landslides: A Case Study of the April 20, 2013 Lushan Earthquake, China, Acta Geologica Sinica (English Edition), Vol. 90, No.2, 2016.04, This Paper proposes a combined method LE-WoE of LE (Logistic Regression) and WoE (Weight of Evidence) for landslide susceptibility mapping by taking their individual merits and overcoming their limitations. By practical applications, the results show that the combined LR-WoE method is of higher accuracy than both the individual method. It can be concluded that the new combined method LE-WoE can provide a promising level of accuracy for earthquake induced landslide susceptibility mapping..
38. Zhao Xingquan, Zhang Yingbin, GUANGQI CHEN, Discontinuous Deformation Analysis Method and Its Applications to Disaster Prevention, Journal of Southwest Jiaotong University, 51, 2, 300-312, 2016.04.
39. Wei Wang, Guangqi Chen, Zheng Han, Suhua Zhou, Hong Zhang, Peideng Jing, 3D numerical simulation of debris-flow motion using SPH method incorporating non-Newtonian fluid behavior, Natural Hazards, 10.1007/s11069-016-2171-x, 81, 3, 1981-1998, 2016.04, Flow-type landslide, such as debris-flow, often exhibits high velocity and long run-out distance. Simulation on it benefits the propagation analysis and provides solution for risk assessment and mitigation design. Previous studies commonly used shallow water assumption to simulate this phenomenon, ignoring the information in vertical direction, and the Bingham model to describe constitutive law of non-Newtonian fluid can cause numerical divergence unless necessary parameter is defined. To address the issue, the full Navier–Stokes equations are adopted to describe the dynamics of the flow-type landslides. Additionally, the general Cross model is employed as the constitutive model, which ensures the numerical convergence. Rheological parameters are introduced from the Bingham model and the Mohr–Coulomb yield criterion. Subsequently, the governing equations incorporating the modified rheological model are numerically built in the smoothed particle hydrodynamics (SPH) framework and implemented into the open-source DualSPHysics code. To illustrate its performance, the 2010 Yohutagawa debris-flow event in Japan is selected as a case study. Parameters regarding the debris magnitude, i.e., the front velocity and section discharge, were also well analyzed. Simulated mass volume and deposition depth at the alluvial fan are in good agreements with the in situ observation. On the basis of the results, the developed method performs well to reproduce the debris-flow process and also benefits the analysis of flow characteristics, affected area for risk assessment and mitigation design..
40. Suhua Zhou, Wei Wang, Guangqi Chen, Baochen Liu, Ligang Fang, A Combined Weight of Evidence and Logistic Regression Method for Susceptibility Mapping of Earthquake-induced Landslides
A Case Study of the April 20, 2013 Lushan Earthquake, China, Acta Geologica Sinica (English Edition), 10.1111/1755-6724.12687, 90, 2, 511-524, 2016.04, The Ms 7.0 Lushan earthquake triggered a huge number of landslides. Landslide susceptibility mapping is of great importance. Weight of Evidence (WoE) and Logistic Regression (LR) methods have been widely used for LSM (Landslide Susceptibility Mapping). However, limitations still exist. WoE is capable of assessing the influence of different classes of each factor, but neglects the correlation between factors. LR is able to analyze the relationship among the factors while it is not capable of evaluating the influence of different classes. This paper proposes a combined method of LR and WoE for LSM, taking advantage of their individual merits and overcoming their limitations. An inventory of 1289 landslides was used: 70% were random-selected for training and the remaining for validation. 11 landslide condition factors were employed in the model and the result was validated using Receiver Operating Characteristic (ROC) curve. The results showed that the LR-WoE model had a better accuracy than the LR model, producing an area below the curve with values of 0.802 success and 0.791 predictive, higher than that of the LR model (0.715 success and 0.722 predictive). It is therefore concluded that the combined method of WoE and LR can provide a promising level of accuracy for earthquake-induced landslide susceptibility mapping..
41. Xingquan Zhao, Yingbin Zhang, Guangqi Chen, Pengcheng Yu, Xiaofu Huagn, Yanyan Chen, Discontinuous deformation analysis method and its applications to disaster prevention, Xinan Jiaotong Daxue Xuebao/Journal of Southwest Jiaotong University, 10.3969/j.issn.0258-2724.2016.02.010, 51, 2, 300-312, 2016.04, In order to explore the characteristics of geological hazards induced by earthquake, the discontinuous deformation analysis (DDA) was used to simulate the failure processes of rock collapses, landslides, and breakwaters under the earthquake loading. Particularly, the influence of the earthquake loading on hazard processes and motions was studied, and new modules were integrated into the current DDA code to obtain the interaction forces. The results show that DDA can be applied to evaluation of landslide mass mobility. The vertical ground motion can remarkably amplify the mobility in the near-fault area. DDA has advantage in the whole-process simulation of landslide induced by earthquake. The simulation results can reflect the characteristics of the failure processes of collapses, landslides and breakwaters faithfully. In addition, DDA is also able to calculate the impact force of failure masses on structures. The peak value of the impact force is much larger than the static lateral pressure, and is four times more than the static lateral pressure in the case study. Hence, the DDA can provide technical guidance for site selection and design of disaster protection from the perspective of reliability and economy..
42. Suhua Zhou, Guangqi Chen, Ligang Fang, Distribution pattern of landslides triggered by the 2014 Ludian earthquake of China
Implications for regional threshold topography and the Seismogenic fault identification, ISPRS International Journal of Geo-Information, 10.3390/ijgi5040046, 5, 4, 2016.04, The 3 August 2014 Ludian earthquake with a moment magnitude scale (Mw) of 6.1 induced widespread landslides in the Ludian County and its vicinity. This paper presents a preliminary analysis of the distribution patterns and characteristics of these co-seismic landslides. In total, 1826 landslides with a total area of 19.12 km2 triggered by the 3 August 2014 Ludian earthquake were visually interpreted using high-resolution aerial photos and Landsat-8 images. The sizes of the landslides were, in general, much smaller than those triggered by the 2008Wenchuan earthquake. The main types of landslides were rock falls and shallow, disrupted landslides from steep slopes. These landslides were unevenly distributed within the study area and concentrated within an elliptical area with a 25-km NW-SE striking long axis and a 15-km NW-SE striking short axis. Three indexes including landslides number (LN), landslide area ratio (LAR), and landslide density (LD) were employed to analyze the relation between the landslide distribution and several factors, including lithology, elevation, slope, aspect, distance to epicenter and distance to the active fault. The results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the more susceptible to co-seismic landslides. The elevation range of high landslide susceptibility was between 900-1300 m and 1800-2000 m. There was a generally positive correlation between co-seismic landslides and slope angle, until a maximum for the slope class 40°-50°. The co-seismic landslides occurred preferably on Southeast (SE), South (S) and Southwest (SW) oriented slopes. Results also show that the landslide concentration tends to decrease with distance from the surface projection of the epicenter rather than the seismogenic fault, and the highest landslide concentration is located within a 5-6 km distance of the seismogenic fault. Regarding the epicenter, the largest landslide clusters were found on the SE, northeast by east (NEE) and nearlyWest (W) of the epicenter. In addition, we also suggest that statistical results of slope gradients of landslides might imply a threshold topography of the study area within a tectonically active background. By analogy with other events, the statistical results of landslides aspects also imply the seismogenic fault of the Ludian earthquake might have been the Northwest (NW)-Trending fault, which is consistent with other studies..
43. Yange Li, Chuan Tang, Zheng Han, Jianling Huang, Linrong Xu, Yi He, Guangqi Chen, Estimating the mud depth of debris flow in a natural river channel
a theoretical approach and its engineering application, Environmental Earth Sciences, 10.1007/s12665-016-5480-1, 75, 8, 2016.04, Mud depth of debris flow is an essential parameter for assessing the hazard magnitude in an event. However, direct prediction of mud depth in a natural river channel is a scientific challenge because current methods often treat the complex relief of bed surface as a rectangular one, which makes the prediction illogical. In this paper, we propose a new theoretical approach, the so-called numerical integral method-based approach for estimating the maximum mud depth of debris flow at a complex cross-section in a natural river channel. Given a predefined peak discharge of the debris-flow event, the numerical integral method-based iteration algorithm uses the Riemann method to search for an approximate mud depth. In contrast to the previous methods, the presented approach addresses an important issue, namely it takes into account the complex shape of the bed surface and superelevation at the bend for natural channels. Two cases are used to illustrate the performance and advantages of the presented approach: one is a well-documented event in the previous study, and the other is a debris-flow event after Ms. 8.0 Wenchuan earthquake. An engineering application regarding the rational design of a debris-flow canal is subsequently discussed. The canal was completely destroyed in a debris flow event in 2008. We used the proposed method to back-analyze the mud depth and velocity in the canal. It was found that the abrupt decrease of mud depth from the natural channel to the concrete canal significantly reduced the transportation capability, thereby causing blockage in the canal. The canal was modified and reconstructed in 2009 with suggested improvements from the proposed method, and successfully transported subsequent debris flow in 2011..
44. Wei Wang, Guangqi Chen, Hong Zhang, Su Hua Zhou, Shu Guang Liu, Yan Qiang Wu, Fu Song Fana, Analysis of landslide-generated impulsive waves using a coupled DDA-SPH method, Engineering Analysis with Boundary Elements, 10.1016/j.enganabound.2015.12.014, 64, 267-277, 2016.03, Large impulsive waves generated by slope failures and a subsequent landslide in a reservoir area may lead to serious damage to the dam, shoreline properties and lives. Therefore, analysis of landslide-generated impulsive waves is of significant importance for hazard prevention and reduction. There are three key points for analyzing this problem: (i) the landslide run-out, (ii) the free surface flow and (iii) the landslide-water interaction process. The Discontinuous Deformation Analysis (DDA) method was previously developed to investigate discontinuous block movements, while the Smoothed Particle Hydrodynamics (SPH) method was used mostly to model free surface flow. However, the solid-fluid interaction is seldom considered in the respective fields, which greatly restricts their applications. For this reason, the coupled DDA-SPH method was proposed in this study to solve the solid-fluid interaction problem. To validate this approach, this study considered a wedge sliding along an inclined plane and interacting with the water body. The corresponding Heinrich's experimental results were adopted to evaluate the accuracy of the coupled method in modeling the landslide movement and wave profile, proving that the landslide motion and wave profiles could be captured accurately by the coupled method. Finally, the effect of the governing parameters on the wave amplitude was discussed..
45. Wei Wang, Guangqi Chen, Kunlong Yin, Yang Wang, Suhua Zhou, Yiliang Liu, Modeling of landslide generated impulsive waves considering complex topography in reservoir area, Environmental Earth Sciences, 10.1007/s12665-016-5252-y, 75, 5, 1-15, 2016.03, The impulsive wave is considered as one of the most notably secondary hazards induced by landslides in reservoir areas. The impulsive wave with considerable wave amplitude is able to cause serious damage to the dam body, shoreline properties and lives. To investigate and predict the wave characteristics, many experimental studies employed the generalized channels rather than the realistic topography. Deviation from the idealized geometries may result in non-negligible effects due to the wave refraction or reflection with complex topography. To consider the topography effect, a prototype scaled experiment was conducted. A series of tests with different collocation of parameters were performed. The experimental results were then summarized to propose empirical equations to predict the maximum wave amplitude, and wave decay in channel direction. The generalized empirical equations can obtain better results for wave features prediction by compared with those derived from the idealized models. Furthermore, a 3D numerical modeling corresponding to the physical experiment was conducted based on the SPH method. The wave characteristics in the sliding and channel directions were investigated in detail including the maximum wave amplitude, wave run-up, wave arrival time and wave crest amplitude decay. The comparison between the simulation and experiment indicates the promising accuracy of the SPH simulation in determining the general features even with complex river topography. Finally, the limitation and applicability of both the experimental and numerical methods in analyzing the practical engineering problems were discussed. Combination of the both methods can benefit the hazard prevention and reduction for landslide generated impulsive waves in reservoir area..
46. GUANGQI CHEN, Modeling of landslide generated waves in Three Gorges Reservoir, China using SPH method, Japanese Geotechnical Society Special Publication, 2016.02.
47. Suhua Zhou, Guangqi Chen, Ligang Fang, Yunwen Nie, GIS-based integration of subjective and objective weighting methods for regional landslides susceptibility mapping, Sustainability, 10.3390/su8040334, 8, 4, 2016, The development of landslide susceptibility maps is of great importance due to rapid urbanization. The purpose of this study is to present a method to integrate the subjective weight with objective weight for regional landslide susceptibility mapping on the geographical information system (GIS) platform. The analytical hierarchy process (AHP), which is subjective, was employed to weight predictive factors' contribution to landslide occurrence. The frequency ratio (FR) method, which is objective, was used to derive subclasses' frequency ratio with respect to landslides that indicate the relative importance of a subclasswithin each predictive factor. A case studywas carried out at Tsushima Island, Japan, using a historical inventory of 534 landslides and seven predictive factors: elevation, slope, aspect, terrain roughness index (TRI), lithology, land cover andmean annual precipitation (MAP). The landslide susceptibility index (LSI) was calculated using the weighted linear combination of factors' weights and subclasses' weights. The study area was classified into five susceptibility zones according to the LSI. In addition, the produced susceptibility map was compared with maps generated using the conventional FR and AHPmethod and validated using the relative landslide index (RLI). The validation result showed that the proposed method performed better than the conventional application of the FR method and AHP method. The obtained landslide susceptibility maps could serve as a scientific basis for urban planning and landslide hazard management..
48. Guangqi Chen, Fusong Fan, Stability analysis of toppling slope using the extended NMM, 50th US Rock Mechanics / Geomechanics Symposium 2016 50th US Rock Mechanics / Geomechanics Symposium 2016, 2, 1344-1349, 2016, The original numerical manifold method (NMM) is extended for stability analysis of a toppling slope with complex sliding surface and cohesion and tensile strengths existing in discontinuities. The extended NMM is shown effective by reproducing a centrifuge test. With NMM simulation, the commonly used Goodman and Bray's analytical method is shown adaptable to a toppling slope model with a simple sliding surface without cohesion and tensile strengths in the discontinuities. It is shown that the deformation of the sliding body has no significant effect on the result. The relationship between dip angle and critical friction angle is investigated. A real toppling slope is simulated and the necessary cohesion and friction angle are verified..
49. GUANGQI CHEN, Integration of Bivariate Statistics and Analytic Hierarchy Process Methods in Regional Landslides Susceptibility Mapping: A case study of Tsushima Island, Japan, Proceedings of the symposium on advanced technology of prediction and preventive measures of landslides, 2015.12.
50. GUANGQI CHEN, Numerical modeling of landslide generated impulsive waves using coupled DDA-SPH method, Proceedings of the symposium on advanced technology of prediction and preventive measures of landslides, 2015.12.
51. GUANGQI CHEN, Modeling of open channel flow for landslide dam formation using smoothed particle hydrodynamics method, Proceedings of the symposium on advanced technology of prediction and preventive measures of landslides, 2015.12.
52. GUANGQI CHEN, Slope unit-based distribution analysis of landslides triggered by the April 20, 2013, Ms 7.0 Lushan earthquake, Arabian Journal of Geosciences, 2015.12.
53. Zheng Han, Guangqi Chen, Yange Li, Yi He, Assessing entrainment of bed material in a debris-flow event
A theoretical approach incorporating Monte Carlo method, Earth Surface Processes and Landforms, 10.1002/esp.3766, 40, 14, 1877-1890, 2015.11, Entrainment of underlying bed sediment by a debris flow can significantly increase the debris-flow magnitude. To study this phenomenon, a theoretical approach to assessing bed-sediment entrainment is presented. The approach is based on a static approximation that bed-sediment entrainment occurs when the shearing stress of the flow is sufficiently high to overcome the basal resistance of the bed sediment. In order to delineate erodible zones in a channel, we analyze the critical condition of this static equilibrium model, and subsequently propose a new concept of a critical line to detect the entrainment reaches in a channel. Considering the spatial and temporal uncertainties of the input parameter, the approach is further incorporated within a Monte Carlo method, and the distribution of entrainment zones and post-entrainment volumes can be analyzed. This approach is illustrated by back-analysis of the 2010 Yohutagawa debris-flow event, Japan. Results from 10 000 trials of Monte Carlo simulation are compared with the in situ surveys. It is shown that the present approach can be satisfactorily used to delineate erodible zones and estimate possible entrainment volume of the event. Discussion regarding the sensitivities and limitations of the approach concludes the paper..
54. Yingbin Zhang, Jinmei Wang, Qiang Xu, Guangqi Chen, John X Zhao, Lu Zheng, Zheng Han, Pengcheng Yu, DDA validation of the mobility of earthquake-induced landslides, Engineering Geology, 10.1016/j.enggeo.2014.08.024, 194, 1069-1075, 2015.09, This paper studies the run-out of earthquake-induced landslides. There are more than 20 mechanical models to explain long run-out of rapid landslides including some earthquake-induced landslides. However, notably few of them considered the effect of seismic loading on the run-out of landslides. In a previous study, we have proposed a model, which is called the multiplex acceleration model (MAM), to interpret the long run-out mechanism, and a shaking-table test has been performed to verify the MAM. Because the previous MAM is a conceptual model and only a single stone has been examined under sine waves by the shaking-table test, the MAM needs to be extended and further verified.In this paper, the MAM was extended by introducing the movement change that was induced by the so-called trampoline effect of earthquake loading, and the latest practical numerical simulation program, discontinuous deformation analysis (DDA), was used to verify the mobility of earthquake-induced landslides. After a conceptual landslide model was used to verify the effect of seismic loading on the mobility, the Donghekou landslide, which was a typical long run-out landslide that was induced by the 2008 Wenchuan earthquake, was analyzed. The results show that: the seismic loading could be one of the factors that could eventually help increase the run-out of landslides..
55. Hong Zhang, Guangqi Chen, Lu Zheng, Zheng Han, Yingbin Zhang, Yan Qiang Wu, Shuguang Liu, Detection of contacts between three-dimensional polyhedral blocks for discontinuous deformation analysis, International Journal of Rock Mechanics and Mining Sciences, 10.1016/j.ijrmms.2015.05.008, 78, 57-73, 2015.09, A new algorithm to detect contacts between three-dimensional (3-D) arbitrarily shaped polyhedral blocks for the discontinuous deformation analysis (DDA) method is presented in this paper. The new algorithm includes three main steps, i.e. neighbor search, contact type examination, and entrance candidate identification, all of which are performed using the general features and relations of geometric elements of polyhedra. First, contact detection begins with searching neighbor blocks and vertices potential to be in contact in order to improve the computation efficiency. Then, pairs of neighbor blocks are examined in more detail for four basic contact types. Finally, corresponding contact points and planes for each contact type are identified by general entrance formulas, which is prepared for the subsequent contact force calculations in the program. The new algorithm has been implemented in the original 3-D DDA program and the extended 3-D DDA program can display the results using OpenGL. Three typical contact examples including concave blocks, i.e. vertex-to-concave-edge, convex-edge-to-concave-edge and vertex-to-concave-vertex contacts are provided to verify the new algorithm. Additionally, a practical example in rock engineering, sliding of a tetrahedral wedge, is also presented, and the 3-DDA results are compared with the analytical solutions..
56. Fan F., GUANGQI CHEN, Numerical study on soil arching effects of stabilizing piles, Memoirs of the Faculty of Engineering, Kyushu University, 2015.07.
57. Zheng Han, Guangqi Chen, Yange Li, Wei Wang, Hong Zhang, Exploring the velocity distribution of debris flows
An iteration algorithm based approach for complex cross-sections, Geomorphology, 10.1016/j.geomorph.2015.03.043, 241, 72-82, 2015.07, The estimation of debris-flow velocity in a cross-section is of primary importance due to its correlation to impact force, run up and superelevation. However, previous methods sometimes neglect the observed asymmetric velocity distribution, and consequently underestimate the debris-flow velocity. This paper presents a new approach for exploring the debris-flow velocity distribution in a cross-section. The presented approach uses an iteration algorithm based on the Riemann integral method to search an approximate solution to the unknown flow surface. The established laws for vertical velocity profile are compared and subsequently integrated to analyze the velocity distribution in the cross-section. The major benefit of the presented approach is that natural channels typically with irregular beds and superelevations can be taken into account, and the resulting approximation by the approach well replicates the direct integral solution. The approach is programmed in MATLAB environment, and the code is open to the public. A well-documented debris-flow event in Sichuan Province, China, is used to demonstrate the presented approach. Results show that the solutions of the flow surface and the mean velocity well reproduce the investigated results. Discussion regarding the model sensitivity and the source of errors concludes the paper..
58. Fusong Fan, Guangqi Chen, Xinli Hu, Wei Wang, Numerical study on soil arching effects of stabilizing piles, Memoirs of the Faculty of Engineering, Kyushu University, 75, 1, 17-27, 2015.07, The Soil arching effect, the transfer of soil pressure from the yielding soil to the piles support, is a phenomena commonly encountered in geotechnical engineering for stabilizing landslides. In this paper, the (finite element method) FEM and (discontinuous deformation analysis) DDA were used to study on the soil arching effects of stabilizing piles in landslides. This paper proposes a method for two dimensional numerical simulation to perform three dimensional soil-pile interaction so that the slope angle can be considered even using a two dimensional numerical method. And then, a FEM model is built based on the FEM to investigate the soil arching effect on stress and deformation distribution in detail for different pile intervals and pile width. The results shown that the soil arching effects do exist and the height of soil arching becomes larger when the pile interval is larger; the soil arching height does not change when the pile width increases, while the shape of soil arching changes. Finally, in order to investigate the failure condition of a stabilizing pile enforced slope, DDA is applied. The results comparison between the example of FEM model and DDA model is conducted to verify the DDA application of solving the continuity problem. Then the failure of model is also analyzed by the simulation of DDA. The results show that the DDA has accordant results with FEM for the small deformation problems, and the DDA can be applied to simulate the large deformation and failure problems of soil arching which cannot be done by FEM..
59. Yingbin Zhang, Jue Zhang, GUANGQI CHEN, Effects of vertical seismic force on initiation of the Daguangbao landslide induced by the 2008 Wenchuan earthquake, Soil Dynamics and Earthquake Engineering, 10.1016/j.soildyn.2014.06.036, 70, 91-102, 2015.06, This paper analyses the effects of vertical seismic force on initiation mechanism of near-fault large-scale landslides by using the Daguangbao landslide induced by the 2008 Wenchuan earthquake as an example. Field investigations showed that tension failure plays an important role in failure mechanism, and the tension failure is due to the effect of a large vertical seismic motion that occurred in the meizoseismal area during the earthquake. Firstly, two key issues in seismic analysis of near-fault large-scale landslide are proposed: i) how to select and correct the severe near-fault excitations with significant co-seismic displacements and ii) how to consider the effect of the landslide scale on estimation of material strength. Then, in order to investigate the effect of the severe vertical seismic force on the initiation of the huge Daguangbao landslide, five cases, 1) static; 2) pseudo-static only-horizontal; 3) pseudo-static horizontal-and-vertical; 4) dynamic only-horizontal; 5) dynamic horizontal-and-vertical, are performed using the finite difference program FLAC3D. The simulation results are presented in terms of tension failure area, factor of safety, and displacement. The results confirm the significant effects of vertical seismic force on seismic slope failure mechanism as the tension failure areas and the displacements observed in the case of horizontal-and-vertical are larger than those observed in the case of only-horizontal..
60. Jue Zhang, GUANGQI CHEN, Integration of Bivariate Statistics and Analytic Hierarchy Process Methods in Regional Landslides Susceptibility Mapping: A case study of Tsushima Island, Japan, Soil Dynamics and Earthquake Engineering, 10.1016/j.soildyn.2014.06.036, 70, 91-102, 2015.06.
61. Zheng Han, Guangqi Chen, Yange Li, Chuan Tang, Linrong Xu, Yi He, Xun Huang, Wei Wang, Numerical simulation of debris-flow behavior incorporating a dynamic method for estimating the entrainment, Engineering Geology, 10.1016/j.enggeo.2015.02.009, 190, 52-64, 2015.05, There is a pressing need to estimate debris-flow entrainment because several lines of studies have substantiated that the magnitude of a debris flow may grow manyfold due to sediment entrainment. In this paper, we present a two-dimensional numerical model of debris-flow behavior for estimating entrainment over complex topography. The model is governed by a numerical integration of the depth-average motion equations using shallow water approximation. The governing equations are numerically solved using the semi-Lagrangian method in an explicit finite difference grid. Compared to previous models, the presented model highlights the importance of entrainment, and incorporates a physically-based dynamic method to estimate the entrainment rate. The entrainment rate can be predicted using reasonable assumptions regarding the velocity profile of the debris flow and the rapidly changing pore pressure of the bed sediment. The stability of the presented model is first illustrated by a hypothesized dam-breaking problem; the effectiveness of the implemented model entrainment process is subsequently tested on the 2010 Yohutagawa debris-flow event in Japan. The test indicates that the presented method can be satisfactorily used to simulate debris-flow behavior and the entrainment process. A discussion regarding the advantages and limitations of the model concludes the paper..
62. Zheng Han, GUANGQI CHEN, Exploring the velocity distribution of debris flows: an iteration algorithm based approach for complex cross-sections, Geomorphology, 241, 72-82, 2015.04.
63. Zheng Han, GUANGQI CHEN, Numerical simulation of debris-flow behavior incorporating a dynamic method for estimating the entrainment, Engineering Geology, 190, 52-64, 2015.03, 土石流の数値シミュレーション手法を開発し、実用的なアプローチの提案により土砂災害防災に寄与できる。.
64. Yingbin Zhang, H. Xing, GUANGQI CHEN, A new movement mechanism of earthquake-induced landslides by considering the trampoline effect of vertical seismic loading, Engineering Geology for Society and Territory, 10.1016/j.soildyn.2014.06.036, 2, 753-758, 2015.02.
65. H. Zhang, Guangqi Chen, L. Zheng, Y. Zhang, Y. Q. Wu, Z. Han, F. S. Fan, P. D. Jing, W. Wang, A new discontinuous model for three dimensional analysis of fluid-solid interaction behavior, International Symposium on Geomechanics from Micro to Macro, IS-Cambridge 2014 Geomechanics from Micro to Macro - Proceedings of the TC105 ISSMGE International Symposium on Geomechanics from Micro to Macro, IS-Cambridge 2014, 1, 503-508, 2015.01, The analysis of interaction behavior between fluid and solid is a topic interested to many researchers due to its wide application in engineering. A new discontinuous model coupling the methods of 3D Discontinuous Deformation Analysis (DDA) and 3D Smoothed Particle Hydrodynamics (SPH) is presented for three dimensional analysis of fluid-solid interaction behavior. The motions of solid element (termed block) are analyzed with 3D DDA method while the motions of the fluid element (termed particle) are simulated using 3D SPH method. The contact type between the particles and the blocks is treated as vertex-to-face contact, thus the impact of fluid is applied as point loading on the blocks which is referred to as "penalty-force" method. A method of particle-block contact detection is developed aiming to judge the entrance facet and maintain the interaction with the identical facet during the process of contact interaction to satisfy the criterion that the blocks should be prevent form penetrating by the particles and push them back directly in the case of high velocity impact. A quick sort and search algorithm of particles in the vicinity of the blocks combined with the method of bounding box is introduced for efficient particle-block contact detection. The coupled SPH-DDA provides a promising computational tool to simulate a variety of fluid-solid interaction problems in many potential applications in hydraulic engineering, coastal and offshore engineering, geomechanical engineering, etc..
66. Yingbin Zhang, Hao Xing, Guangqi Chen, Lu Zheng, A new movement mechanism of earthquake-induced landslides by considering the trampoline effect of vertical seismic loading, Engineering Geology for Society and Territory - Volume 2: Landslide Processes, 10.1007/978-3-319-09057-3_127, 753-757, 2015.01, This paper presents a new explanation for large-scale long run-out earthquake-induced landslides by considering the trampoline effect of earthquake loading. Long run-out is one of the major features of the earthquake-induced landslides, especially for those large-scale landslides. Since the long run-out mechanism of earthquake-induced landslides is still not clear, a new run-out model was presented on the basis of the so-called trampoline effect of vertical earthquake loading, and a practical numerical simulation program based on discontinuous deformation analysis (DDA) was developed to clarify movement behaviours of earthquake-induced landslides by incorporating the trampoline effect. This new mechanism was applied to explain some complicated phenomena appeared in large-scale long run-out landslides induced by the 2008 Wenchuan earthquake. A typical long run-out landslides induced by the 2008 Wenchuan earthquake, Donghekou landslide, was analysed in practical numerical simulation. The results show that the presented new long run-out model is reasonable and applicable. ..
67. Z. Han, Guangqi Chen, Y. Li, H. Zhang, F. Fan, P. Jing, W. Wang, S. Zhou, L. Xu, S. Chen, Development of the cellular automaton model for simulating the propagation extent of debris flow at the alluvial fan
A case study of Yohutagawa, Japan, International Symposium on Geomechanics from Micro to Macro, IS-Cambridge 2014 Geomechanics from Micro to Macro - Proceedings of the TC105 ISSMGE International Symposium on Geomechanics from Micro to Macro, IS-Cambridge 2014, 2, 983-988, 2015.01, As a two-phase anisotropic mixture, debris flowshows some complex fluid-dynamical characteristics on its motion behavior, which makes it difficult to be modelled or simulated through standard approaches. Consequently, Cellular Automaton (CA) model in the field of parallel computing, which has long been verified as efficiently applying in the simulation of complex natural process, are recently introduced to simulate flow-type phenomena. In this paper, the components of CA model for debris-flow simulation are reviewed, after that a two-dimensional cellular space is generated from the Digital Terrain Model (DTM) with 2.5m high-resolution, and the relationship of lattices in the space is defined as Moore neighborhood type. A new transition function, aiming at flow direction determination, is proposed through the way that implementing the debris-flow inertial influence into the traditional topography-based D8 algorithm, by a multiplying equation or an addition equation. We also present a three-step propagation algorithm to integrate the single flow routines, then use the constant discharge model to assign the flow depth to each routine, in this way the propagation area can be gradually delineated through each increment step. We test the developed model with CH87 Brichboden debris-flow event, and illustrate its application withYohutagawa debris-flow event in Japan, 2010. Results of both cases show that a more accurate propagation perimeter pattern is observed using addition equation in the modified flow direction algorithm, comparing to the traditional D8 algorithm and multiplying equation-based algorithm..
68. Guangqi Chen, Yanan Fan, Yange Li, Hazard mapping of landslide-dam induced by earthquake, 10.3208/jgssp.JPN-115, 1103-1106, 2015.01, A landslide-dam hazard mapping method is proposed so as to provide the necessary information to countermeasures against earthquake induced landslide disaster chain. The procedures of the method are introduced together with newly developed slope identification technique and new slope stability analysis GIS module. A practical application is presented to show the practical usefulness of the hazard mapping system..
69. Zheng Han, Guangqi Chen, A method for estimating the bed-sediment entrainment in debris flow, 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability, 10.3208/jgssp.JPN-033, 1089-1093, 2015, The immense destructive impact induced by debris flow in mountainous region endangers human lives and infrastructure facilities. Previous studies have long indicated that the fatalities in a debris-flow event depend on the volume of debris flow, which may be conspicuously amplified by entraining bed-sediment along the trajectory as it descends the slope. Several lines of evidence by the previous studies have also highlighted this viewpoint that debris flow can grow dramatically in magnitude as accompanying by the entrainment. In this paper, we present an elementary model to estimate the dynamic entrainment rate of bed-sediment when overridden by debris flow. Following the preliminary studies done by Iverson (2012) and Medina et al. (2008), a temporal entrainment rate can be computed basing on the momentum conservation of the two-layer system. To take into account the influence of the pore water pressure on the entrainment rate, we employ two parameters, λ1 and λ2 into the model, which denote the saturate degree of debris flow and bed-sediment, respectively. Our approach demonstrates that if flow layer and bed layer shares the same friction angle, the condition λ21 should be satisfied to provoke the entrainment. The performance of the approach is firstly tested on a simple scenario with the parameters of typical value, and then a debris-flow event that occurred in 2010 at the Yohutagawa torrent, Japan. The computed entrainment rate and accumulated depth show a good agreement with the in-situ surveys. Another advantage of our approach rests on the fact that entrainment rate is written in a differential form, thus it can be easily incorporated to the mass constitutive equation of the numerical model using a shallow water approximation..
70. Wei Wang, Guangqi Chen, Kunlong Yin, Suhua Zhou, Peideng Jing, Lixia Chen, Modeling of landslide generated waves in Three Gorges Reservoir, China using SPH method, 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability, 10.3208/jgssp.ATC1-3-07, 1183-1188, 2015, To investigate the wave characteristics generated by subaerial landside in Three Gorges Reservoir, China, a large laboratory physical experiment was conducted. Specially, the channel of Baishuihe landslide in the reservoir was selected as prototype and reproduced with scale of 1:200 under the similarity conditions. A series of test with different collocation of parameters were performed. Empirical equations were derived by the means of dimensionless analysis and multiple nonlinear regression. The proposed equations were then used to quickly predict the wave features (maximum wave amplitude, runup, and wave attenuation) of Gongjiafang landslide in the Wu Gorge. Numerical simulation of waves generated by Gongjiafang landslide was carried out using DualSphysics which is a SPH method based application. Comparison between the wave features derived from the numerical simulation and the prediction equations was looked insight. Results show better agreements of both methods either in maximum wave amplitude and runup. In Addition, wave characteristics (wave length, velocity and period) were well analyzed using the wave gauges' data in the numerical simulation. It can be concluded that the modeling work using SPH method should be well adopted in investigating the problems of landslide generated waves in detail, while the equations derived from the experiment enable a quick basis in the prediction of the main wave features. Combination of both methods will be an excellent way in analyzing the practical case and thus provides significant means for hazard assessment and prevention..
71. GUANGQI CHEN, An assessment on the functional effects of the existing preventive structures during landslides, International Journal of Landslide and Environment, 2014.12.
72. Yange LI, GUANGQI CHEN, Zheng Han, A hybrid automatic thresholding approach using panchromatic image for rapid mapping of landslides, GIScience and Remote Sensing, 51, 6, 710-730, 2014.11.
73. Zheng Han, GUANGQI CHEN, Elementary analysis on the bed-sediment entrainment by debris flow and its application using the TopFlowDF model, Geomatics, Natural Hazards and Risk, 10.1080/19475705.2014.966868, 2014.10.
74. T. K. Nian, K. Liu, GUANGQI CHEN, Seismic stability for slopes with multi-row anchors, The Proceedings of the 4th International Conference on Geotechnical Engineering for Disaster Mitigation and Rehabilitation, 543-546, 2014.09, Anchor or pre-stress anchor is one of the most effective countermeasures to stabilize the landslides
and potential unstable slopes in seismically active zone. In this paper, the seismic stability of slope
reinforced with multi-row anchors is analyzed using the pseudo-static approach. Considering the presence of multi-row anchors and vertically seismic acceleration, the upper-bound approach of limit analysis is employed to solve the seismic yield acceleration and the corresponding critical log-spiral failure mechanism. The force provided by anchors is simplified as an axial force, and the seismic load is regarded as pseudo-static body force acting at the center of gravity of the sliding mass. An least upper bound solution of the yield acceleration is obtained based on mathematical optimization method. Furthermore, a series of parametric study is carried out to illustrate the influence of vertical acceleration and anchor position on the stability of slopes..
75. Yingbin Zhang, Qiang Xu, GUANGQI CHEN, Extension of discontinuous deformation analysis and application in cohesive-frictional slope analysis, International Journal of Rock Mechanics and Mining Sciences, 70, 533- 545, 2014.09, This paper extends the discontinuous deformation analysis (DDA) by using an additional evaluation of edge-to-edge contact, with the aim that it can be used to accurately model the failure behaviour of joints dominated by both cohesion and interface friction angle. The original DDA can deal well with the effects of interface friction angle. However, when cohesion exists, DDA results often show an inscrutable behaviour, i.e. a slope may be unstable even if the cohesion is much greater than the theoretical value required for its critical stability. After many detailed investigations and validations, joint contact treatment was found to be the key reason why the original DDA cannot simulate the cohesive material accurately, in which every edge-to-edge contact is treated as two vertex-to-edge contacts that may have different contact states associated with different cohesion treatments. In order to solve this problem, an additional contact type determination process for an edge-to-edge contact was added into the original computer code to avoid the unreasonable situation when two contact states exist in one joint. Several examples were performed to illustrate the accuracy of the modified code and a real landslide case was analysed by using the improved DDA to estimate the shear strength on the interface. Our results show that the improved DDA can simulate the failure of cohesive-frictional material accurately..
76. Zheng Han, GUANGQI CHEN, A new approach for analyzing the velocity distribution of debris flows at typical cross-sections, Natural Hazards, 74, 3, 2053-2070, 2014.06, The asymmetrical distribution of debris-flow velocity in a cross-section has long been observed and is currently regarded as one of the most essential issues in debrisflow research. Due to a lack of quantitative models for the velocity distributions of debris flows, most studies consider only the mean velocity. However, to optimize countermeasure structures, to estimate the erosion rate, or to evaluate the constitutive equations for shear behavior, it is beneficial to know the velocity profile in a cross-section. In this paper, a generalized model of typical channel geometries (e.g., rectangular, trapezoid, or V-shape) is proposed. A description of the velocity distribution that optimizes the Manning–Strickler velocity equation for transverse distribution and Egashira’s velocity equation for vertical distribution is presented; thus, the debris-flow velocity at any point in the cross-section can be calculated and the distribution profile therefore obtained. A well-documented debrisflow reference case and the Jiasikou debris flow in the high-seismic-intensity zone of the Wenchuan earthquake are selected as case studies to demonstrate the model. Analyses of both cases confirm the asymmetrical distribution of debris-flow velocity in cross-section,as originally expected. This shows that the velocity at the top surface in the middle of the channel is much larger than that at each sidewall and than the mean value calculated by former equations. The obtained velocity distribution profile is a better approximation of the observed field profiles.
77. Guruh Samodra, GUANGQI CHEN, Automated landform classification in a rockfall-prone area, Gunung Kelir, Java, European Geosciences Union, 10.5194/esurf-2-339-2014, 2, 239-248, 2014.06, This paper presents an automated landform classification in a rockfall-prone area. Digital terrain models (DTMs) and a geomorphological inventory of rockfall deposits were the basis of landform classification analysis. Several data layers produced solely from DTMs were slope, plan curvature, stream power index, and shape complexity index; whereas layers produced from DTMs and rockfall modeling were velocity and energy. Unsupervised fuzzy k means was applied to classify the generic landforms into seven classes: interfluve, convex creep slope, fall face, transportational middle slope, colluvial foot slope, lower slope and channel bed. We draped the generic landforms over DTMs and derived a power-law statistical relationship between the volume of the rockfall deposits and number of events associated with different landforms. Cumulative probability density was adopted to estimate the probability density of rockfall volume in four generic landforms, i.e., fall face, transportational middle slope, colluvial foot slope and lower slope. It shows negative power laws with exponents 0.58, 0.73, 0.68, and 0.64 for fall face, transportational middle slope, colluvial foot slope and lower slope, respectively. Different values of the scaling exponents in each landform reflect that geomorphometry influences the volume statistics of rockfall. The methodology introduced in this paper has possibility to be used for preliminary rockfall risk analyses; it reveals that the potential high risk is located in the transportational middle slope and colluvial foot slope..
78. T. K. Nian, K. Liu, D. F. Zheng, GUANGQI CHEN, Limit Analysis of Anchored Slopes Subjected to Seismic Loading, Advances in Soil Dynamics and Foundation Engineering GSP 240 © ASCE 2014, 548-553, 2014.05, The seismic stability of an earth slope reinforced with a row of anchors is analyzed within the framework of pseudo-static approach. First, the upper-bound approach of limit analysis combined with strength reduction technique is employed to solve the safety factor and the corresponding critical log-spiral failure mechanism for a given slope. Then, the slope reinforced with a row of anchors is considered, the analytical expressions for calculating the safety factor are derived.The reasonability of solutions is fully verified by comparison with the known solutions from different methods. Further, a pseudo-static seismic load is applied to the anchored slope, and the new analytical formula is also built. Finally, the parametric study is carried out to illustrate the effect.
79. Lu Zheng, GUANGQI CHEN, Yingbin Zhang, The slope modeling method with GIS support for rockfall analysis using 3D DDA, Geomechanics and Geoengineering: An International Journal, 10.1080/17486025.2013.871070, 9, 2, 142-152, 2014.02.
80. Nian Tinkai, Yingbin Zhang, Lu Zheng, GUANGQI CHEN, Failure process simulation of highly jointed rock slope with a fault, Applied Mechanics and Materials, 10.4028/www.scientific.net/AMM.501-504.12, 501, 12-15, 2014.01.
81. Yange Li, Guangqi Chen, Zheng Han, Lu Zheng, Feilian Zhang, A hybrid automatic thresholding approach using panchromatic imagery for rapid mapping of landslides, GIScience and Remote Sensing, 10.1080/15481603.2014.972867, 51, 6, 710-730, 2014.01, In this paper, we propose a hybrid approach for the rapid mapping of landslides, based on automatic thresholding using panchromatic (PAN) images as data sources. The new approach is a combination of image differencing, a multistage local thresholding strategy, and a newly developed directional recursive method. Firstly, the Otsu method has been selected to calculate the global threshold of the entire residual image and the image is repeatedly segmented into sub-images with a growing window size. Secondly, the resulting sub-images are categorized into three types (balanced, background-dominated, and object-dominated) according to the histogram of global and local image information. Thirdly, sub-images of different types are binarized respectively by using different schemes of the proposed directional recursive method. Finally, the individual results in each running step are integrated and the entire image is binarized. The proposed approach has been tested for rapid detection of landslides induced by the Wenchuan earthquake in Beichuan County, China. Results show that almost all of the landslides are properly detected including the low-contrast ones, which cannot be identified neither by the original Otsu method nor the change detection algorithm within ERDAS software..
82. Zheng Han, Guangqi Chen, Yange Li, Linrong Xu, Lu Zheng, Yingbing Zhang, A new approach for analyzing the velocity distribution of debris flows at typical cross-sections, Natural Hazards, 10.1007/s11069-014-1276-3, 74, 3, 2053-2070, 2014.01, The asymmetrical distribution of debris-flow velocity in a cross-section has long been observed and is currently regarded as one of the most essential issues in debrisflow research. Due to a lack of quantitative models for the velocity distributions of debris flows, most studies consider only the mean velocity. However, to optimize countermeasure structures, to estimate the erosion rate, or to evaluate the constitutive equations for shear behavior, it is beneficial to know the velocity profile in a cross-section. In this paper, a generalized model of typical channel geometries (e.g., rectangular, trapezoid, or V-shape) is proposed. A description of the velocity distribution that optimizes the Manning–Strickler velocity equation for transverse distribution and Egashira’s velocity equation for vertical distribution is presented; thus, the debris-flow velocity at any point in the cross-section can be calculated and the distribution profile therefore obtained. A well-documented debrisflow reference case and the Jiasikou debris flow in the high-seismic-intensity zone of the Wenchuan earthquake are selected as case studies to demonstrate the model. Analyses of both cases confirm the asymmetrical distribution of debris-flow velocity in cross-section, as originally expected. This shows that the velocity at the top surface in the middle of the channel is much larger than that at each sidewall and than the mean value calculated by former equations. The obtained velocity distribution profile is a better approximation of the observed field profiles..
83. Yingbin Zhang, Qiang Xu, Guangqi Chen, John X. Zhao, Lu Zheng, Extension of discontinuous deformation analysis and application in cohesive-frictional slope analysis, International Journal of Rock Mechanics and Mining Sciences, 10.1016/j.ijrmms.2014.06.005, 70, 533-545, 2014.01, This paper extends the discontinuous deformation analysis (DDA) by using an additional evaluation of edge-to-edge contact, with the aim that it can be used to accurately model the failure behaviour of joints dominated by both cohesion and interface friction angle. The original DDA can deal well with the effects of interface friction angle. However, when cohesion exists, DDA results often show an inscrutable behaviour, i.e. a slope may be unstable even if the cohesion is much greater than the theoretical value required for its critical stability. After many detailed investigations and validations, joint contact treatment was found to be the key reason why the original DDA cannot simulate the cohesive material accurately, in which every edge-to-edge contact is treated as two vertex-to-edge contacts that may have different contact states associated with different cohesion treatments. In order to solve this problem, an additional contact type determination process for an edge-to-edge contact was added into the original computer code to avoid the unreasonable situation when two contact states exist in one joint. Several examples were performed to illustrate the accuracy of the modified code and a real landslide case was analysed by using the improved DDA to estimate the shear strength on the interface. Our results show that the improved DDA can simulate the failure of cohesive-frictional material accurately..
84. L. Zheng, Guangqi Chen, Y. B. Zhang, Investigating the influence of rock-shape on rockfall dynamics using 3-D DDA, 8th Asian Rock Mechanics Symposium, ARMS 2014 ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014, 2858-2867, 2014.01, Rockfall is one of the most frequent, major hazards in mountainous areas and along engineered slopes worldwide. Accurate estimation of rockfall dynamics is essential for rockfall risk assessment, design and performance evaluation of preventive structures. Although many rockfall simulation codes have been developed, a major variable involved in rockfalls, the rock-shape, which strongly affects the rockfall events, is still poorly considered. Three dimensional discontinuous deformation analysis (3-D DDA) is an effective and helpful tool on rockfall analysis which can explicitly account for rock-shape. In this paper, a practical 3-D DDA code is demonstrated to be capable of simulating free falling, rolling, sliding, and bouncing with high accuracy, which indicates the implemented code is capable of providing reliable rockfall analysis. Rockfall simulations are performed on both idealized incline planes as well as bin-planar slopes. Particle shape index has been induced to investigate the influence of rock-shape after impacts occurred. The rockfall movement behaviors: lateral dispersion and jump height are used to obtain the influence of rock-shape. The analysis provides a more detail description of rock masses and useful information on consideration of rock-shape in rockfall simulation..
85. T. K. Nian, K. Liu, D. F. Zheng, Guangqi Chen, Limit analysis of anchored slopes subjected to seismic loading, 2014 GeoShanghai International Congress: Advances in Soil Dynamics and Foundation Engineering Advances in Soil Dynamics and Foundation Engineering - Selected Papers from the Proceedings of the 2014 GeoShanghai International Congress, 10.1061/9780784413425.056, 548-553, 2014, The seismic stability of an earth slope reinforced with a row of anchors is analyzed within the framework of pseudo-static approach. First, the upper-bound approach of limit analysis combined with strength reduction technique is employed to solve the safety factor and the corresponding critical log-spiral failure mechanism for a given slope. Then, the slope reinforced with a row of anchors is considered and the analytical expressions for calculating the safety factor are derived. The reasonability of solutions is fully verified by comparison with the known solutions from different methods. Further, a pseudo-static seismic load is applied to the anchored slope, and the new analytical formula is also built. Finally, the parametric study is carried out to illustrate the effect of anchor orientation, anchor position, and seismic loading on slope stability..
86. Yingbin Zhang, GUANGQI CHEN, Lu Zheng, Effects of near-fault seismic loadings on run-out of large-scale landslide: A case study, Engineering Geology, 166, 216-236, 2013.11, This study presents the run-out analysis of the Daguangbao landslides subjected to near-faultmulti-direction earthquake forces using discontinuous deformation analysis (DDA). The Daguangbao landslide is the largest landslide induced by the 2008 Wenchuan earthquake. In order to investigate the effects of near-fault seismic force on landslide run-out, kinematic behavior of sliding mass is simulated by a dynamic discrete numerical analysis method called DDA. In this simulation, based on the shape of failure surface and the feature of slope geology, thewhole slope is divided into three parts: base block, upper sliding mass, and lower slidingmass. Then two slidingmasses are divided into the smaller discrete deformable blocks based on pre-existing discontinuities. Size effect of the huge landslide is also considered. Baseline corrected real horizontal and vertical ground motions are taken as volume force acting to the base block. The results show that seismic force has a significant influence on the landslide progression, sliding distance, and shape of post-failure. Results of the horizontal-and-vertical situation are in good agreement with those obtained from post-earthquake field investigation, remote sensing image and description fromthe survivors..
87. Yingbin Zhang, Guangqi Chen, Lu Zheng, Yange Li, Jian Wu, Effects of near-fault seismic loadings on run-out of large-scale landslide
A case study, Engineering Geology, 10.1016/j.enggeo.2013.08.002, 166, 216-236, 2013.11, This study presents the run-out analysis of the Daguangbao landslides subjected to near-fault multi-direction earthquake forces using discontinuous deformation analysis (DDA). The Daguangbao landslide is the largest landslide induced by the 2008 Wenchuan earthquake. In order to investigate the effects of near-fault seismic force on landslide run-out, kinematic behavior of sliding mass is simulated by a dynamic discrete numerical analysis method called DDA. In this simulation, based on the shape of failure surface and the feature of slope geology, the whole slope is divided into three parts: base block, upper sliding mass, and lower sliding mass. Then two sliding masses are divided into the smaller discrete deformable blocks based on pre-existing discontinuities. Size effect of the huge landslide is also considered. Baseline corrected real horizontal and vertical ground motions are taken as volume force acting to the base block. The results show that seismic force has a significant influence on the landslide progression, sliding distance, and shape of post-failure. Results of the horizontal-and-vertical situation are in good agreement with those obtained from post-earthquake field investigation, remote sensing image and description from the survivors..
88. Jian Wu, GUANGQI CHEN, Lu Zheng, Yingbin Zhang, GIS-based numerical modelling of debris flow motion across three-dimensional terrain, Journal of Mountain Science, 10, 4, 522-531, 2013.10, The objective of this study is to incorporate a numerical model with GIS to simulate the movement, erosion and deposition of debris flow across the three dimensional complex terrain. In light of the importance of erosion and deposition processes during debris flow movement, no entrainment assumption is unreasonable. The numerical model
considering these processes is used for simulating debris flow. Raster grid networks of a digital elevation model in GIS provide a uniform grid system to describe complex topography. As the raster grid can be used as the finite difference mesh, the numerical model is solved numerically using the Leap-frog finite difference method. Finally, the simulation results can be displayed by GIS easily and used to debris flow evaluation. To illustrate this approach, the proposed
methodology is applied to the Yohutagawa debris flow that occurred on 20th October 2010, in Amami-Oshima area, Japan. The simulation results that reproduced the movement, erosion and deposition are in good agreement with the field investigation. The effectiveness of the dam in this real-case is also verified by this approach. Comparison with the results
were simulated by other models, shows that the present coupled model is more rational and effective..
89. Y. Li, Guangqi Chen, L. Zheng, Z. Han, J. L. Huang, Assessment of functional effects of the existing preventive structures during landslides, 307-311, 2013.10, Many landslide prone slopes were identified in Japan and preventive structures were implemented against them. However, property damage and life loss were still caused by landslide despite of existing preventive structures. Therefore, the validity of existed structures should be investigated. The Discontinuous Deformation Analysis (DDA) is considered as an appropriate numerical tool to resolve this problem since it can reproduce the process of landslide movement after failure. In this paper, both landslide with or without preventive structures is simulated to assess the validity of preventive structures by using DDA. Moreover, different cases are carried out to determine the appropriate position of the building according to the change trend of impact force. Results show that the assessment is acceptable and believable, the calculated impact forces on the building at different locations can be used to future preventive design..
90. Y. Zhang, Guangqi Chen, L. Zheng, J. Wu, Detailed investigation of near-fault earthquake loading induced displacement of sliding system by the Discontinuous Deformation Analysis (DDA), 153-160, 2013.10, In this paper, a detailed validation of dynamic block is carried out by extended Discontinuous Deformation Analysis (DDA). A rigorous analytical model for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane is proposed in which ground shakings are applied on base block or dynamic block in direction of either horizontally or parallel to the inclined plane, with or without a simultaneous vertical component of motion. Both analytical solution and DDA simulation results for 6 cases (block on an inclined plane, subjected to only-horizontal or horizontal-and-vertical seismic force, and excitation applied on base block or dynamic block) are presented. Two idealized wavelets and one group of accelerograms are used as excitation. Comparisons of the theory solution and DDA results for different cases are carried out. The Results show that DDA can simulate the movement of dynamic block successfully and give accurate results..
91. Yanan Fan, Guangqi Chen, Kiyonobu Kasama, Yange Li, Susceptibility Zonation of earthquake induced landslide-dams at the catchment of Tongkou river, China, Memoirs of the Faculty of Engineering, Kyushu University, 73, 2, 57-70, 2013.10, Significant hazards may occur due to large landslide-dams formed by earthquake induced landslides. Those landslide-dams present serious threats to both life and property from possible upstream flooding when the impounded lake water level rises, and possible dam failure and downstream flooding with rapid release of impounded water. In order to prevent those secondary disasters, we made an assumption that the landslide-dams are only formed when a large amount of landslide deposits directly rush into a river with moderate or high-velocities. Then a practical prediction method is presented to extract the dangerous slopes which are thought as the sources of earthquake induced landslide-dams. The prediction procedure consists of the following steps: (1) identification of all the slopes using spatial statistics; (2) the extraction of potential slopes according to our assumption using three spatial relation filters; (3) stability analysis to determine landslide prone slopes and volume estimation of potential landslide deposits using Limit Equilibrium Analysis. (4) susceptibility mapping by ranking the exact slopes. This method has been used to extract slopes those are potential to collapse and form landslide-dams in the catchment of Tongkou river after the 2008 Wenchuan earthquake, China. Results show that the proposed method is effective and efficient..
92. Yingbin Zhang, GUANGQI CHEN, Lu Zheng, An analytical method for evaluating the effects of turning corner on 3D slope stability, Computers and Geotechnics, 50, 40-45, 2013.09, The cut complement method (CCM) used to evaluate the effect of a turning corner is discussed in this paper. It is crucial to evaluate the turning corner effect in three-dimensional (3D) slope engineering because this effect may influence the slope stability. CCM determines the criticality of opposing effects by comparing the stabilities of the different components of a turning corner slope (turning, virtual and common components). These effects depend on the slope angle and the cohesion and internal friction angle. CCM determines the critical slope angles for a turning slope with different shear strengths. These results are presented graphically to facilitate the safe and economic design and the reinforcement of corner turning slopes..
93. Yana FAN, GUANGQI CHEN, Susceptibility Zonation of Earthquake induced Landslide-dams at the Catchment of Tongkou River, China, Memoirs of the Faculty of Engineering, Kyushu University, 73, 2, 57-70, 2013.09.
94. Yingbin Zhang, Guangqi Chen, Bo Wang, Liang Li, An analytical method to evaluate the effect of a turning corner on 3D slope stability, Computers and Geotechnics, 10.1016/j.compgeo.2013.05.002, 53, 40-45, 2013.09, The cut complement method (CCM) used to evaluate the effect of a turning corner is discussed in this paper. It is crucial to evaluate the turning corner effect in three-dimensional (3D) slope engineering because this effect may influence the slope stability. CCM determines the criticality of opposing effects by comparing the stabilities of the different components of a turning corner slope (turning, virtual and common components). These effects depend on the slope angle and the cohesion and internal friction angle. CCM determines the critical slope angles for a turning slope with different shear strengths. These results are presented graphically to facilitate the safe and economic design and the reinforcement of corner turning slopes..
95. GUANGQI CHEN, Zheng Lu, Yingbin Zhang, Practical applications of DDA to disaster prevention, The 11th International Conference on Analysis of Discontinuous Deformation (ICADD11) , 15-28, 2013.08, Some of practical applications of DDA to disaster prevention in Kyushu University are introduced. The first application is to analyze stability of breakwater by considering tsunami induced see page. A local piping mode and global failure mode are clarified by DDA simulations. The second application is to analyze stability and simulate cave-in phenomenon for sand beach. An approach of using DDA to continuous material like sand ground is proposed by generating proper artificial mesh. The bearing capacity and arch function are clarified for the sand ground with a cave. The cave-in phenomenon is reshown by DDA simulations. The third application is to clarify the mechanism of extreme earthquake wave based on so-called trampoline effect and ping-pong model. The extreme waveform with a PGA of more than 4000 gal recorded in Japan is reshown by DDA simulation. These applications will play an important role in disaster prevention in future..
96. Yingbin Zhang, GUANGQI CHEN, Zheng Lu, Detailed investigation of near-fault earthquake loading induced displacement of sliding system by the Discontinuous Deformation Analysis (DDA), The 11th International Conference on Analysis of Discontinuous Deformation (ICADD11) , 153-160, 2013.08, In this paper, a detailed validation of dynamic block is carried out by extended Discontinuous Deformation Analysis (DDA). A rigorous analytical model for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane is proposed in which ground shakings are applied on base block or dynamic block in direction of either horizontally or parallel to the inclined plane, with or without a simultaneous vertical component of motion. Both analytical solution and DDA simulation results for 6 cases (block on an inclined plane, subjected to only-horizontal or horizontal-and-vertical seismic force, and excitation applied on base block or dynamic block) are presented. Two idealized wavelets and one group of accelerograms are used as excitation. Comparisons of the theory solution and DDA results for different cases are carried out. The Results show that DDA can simulate the movement of dynamic block successfully and give accurate results..
97. Zheng Lu, GUANGQI CHEN, Yingbin Zhang, Rock mass stability analysis based on contact mode using DDA, The 11th International Conference on Analysis of Discontinuous Deformation (ICADD11) , 161-167, 2013.08, This paper firstly introduces the process in contact calculation between blocks of Discontinuous Deformation Analysis (DDA) and validates its precision. The contact mode judged after Open-Close iteration is also accurate since the contact force calculation is based on the rigorous equilibrium equations. Therefore, the detachment between two neighboring blocks along joints could be identified quickly and accurately. Based on this, we propose a new approach to search the failure surface in rock mass automatically based on contact mode information. At last, combining with Shear Strength Reduction method (SSR), DDA has been used to analyze the stability of model rock slope using the new proposed failure criterion. Comparing with analytical solution, it is shown that our new approach is applicable and accurate..
98. Yanqiang Wu, GUANGQI CHEN, Zaisen Jiang, The mathematical algorithm of multi-point constraints in the simulations of three-dimensional Numerical Manifold Method, The 11th International Conference on Analysis of Discontinuous Deformation (ICADD11) , 335-340, 2013.08, In this paper, we introduce the parameter adjustment method with condition equations(one surveying adjustment method in geodetic data processing) to three-dimensional Manifold Method through formula derivation, and present the strict-constraint solution and least-squares solution strategies. In least-square solution, we develop the power conception of surveying adjustment and use power ratio to balance the physical and mathematical equations. Then, we use the uniaxial tensile model to verify the validity of above two solution strategies, and analyze their difference. Furthermore, the shearing failure simulation with mathematical constraint is presented. In conclusion, the essential difference of above two strategies is that the strict-constraint strategy can realize strong constraint on some unknowns and have minimum influence on others in the examples of this paper. On the other hand, the least-square strategy influences more than constrained unknowns, and perhaps affects the whole equations. Furthermore, we can control the constraint intensity by adjusting power ratio when using least-square strategy, because the constraint intensity is directly proportional to the power ratio..
99. Zheng Han, GUANGQI CHEN, Yange Li, A numerical simulation of volumetric enlargement for seismic debris flow using integrated DDA and KANAKO 2D, The 11th International Conference on Analysis of Discontinuous Deformation (ICADD11) , 281-287, 2013.08, The assessment of the debris-flow hazard potential has to rely on the debris volume, for now seismic condition and relevant influence is not considered in the current estimation method, which causing the calculating volume far less than reality. Current researches indicate that volumetric enlargement for seismic debris flow mostly due to the debris material accumulation along the flowing path induced by earthquake, however only qualitative or semi-quantitative methods are adopted. In this paper, a method integrating with DDA and dilatant flow model based KANAKO 2D is proposed, in which the process of debris material accumulation is simulated by DDA, the processes of debris material entrainment and debris-flow deposition are simulated by KANAKO 2D. To demonstrate this method, Shekeniluo debris flow gully, which located in the high seismic intensity zone of Wenchuan earthquake in Shimian County, Sichuan Province is selected as a case study. Numerical simulation results show that debris volume and influence area would expand to 3 times, and it is also verified to approximate to the investigation result..
100. Jian Wu, Guangqi Chen, Lu Zheng, Ying bin Zhang, GIS-based numerical modelling of debris flow motion across three-dimensional terrain, Journal of Mountain Science, 10.1007/s11629-013-2486-y, 10, 4, 522-531, 2013.08, The objective of this study is to incorporate a numerical model with GIS to simulate the movement, erosion and deposition of debris flow across the three dimensional complex terrain. In light of the importance of erosion and deposition processes during debris flow movement, no entrainment assumption is unreasonable. The numerical model considering these processes is used for simulating debris flow. Raster grid networks of a digital elevation model in GIS provide a uniform grid system to describe complex topography. As the raster grid can be used as the finite difference mesh, the numerical model is solved numerically using the Leap-frog finite difference method. Finally, the simulation results can be displayed by GIS easily and used to debris flow evaluation. To illustrate this approach, the proposed methodology is applied to the Yohutagawa debris flow that occurred on 20th October 2010, in Amami-Oshima area, Japan. The simulation results that reproduced the movement, erosion and deposition are in good agreement with the field investigation. The effectiveness of the dam in this real-case is also verified by this approach. Comparison with the results were simulated by other models, shows that the present coupled model is more rational and effective..
101. L. Zheng, Guangqi Chen, Y. Zhang, H. Zhang, Review of rock stability analysis using discontinuous deformation analysis (DDA), 3rd ISRM Symposium on Rock Characterisation, Modelling and Engineering Design Methods, SINOROCK 2013 Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, 491-500, 2013.07, Since 1990s, researchers in the discontinuous deformation analysis (DDA) community have dedicated a great deal of effort on the stability analysis of slopes, tunnels and caverns. This paper contains a summary of more than 80 published papers or theses concerning stability analysis using DDA. These studies are grouped into the following two categories: (a) validations with respect to analytical solutions, laboratory experiment results or field data; and (b) applications of rock stability analysis using DDA. After reviewing the validations and variety applications, we are focusing on discussing recent issue in this research filed: limitations and solutions concerning cohesive-friction in DDA stability analysis. Addressed by this review, we find that DDA can perform more than adequately in stability analysis for a variety of engineering problems. In addition, we present a general solution for modeling rock masses behaviors with cohesive-friction joints..
102. Yana FAN, GUANGQI CHEN, Susceptibility analysis of earthquake induced landslide-dam based on GIS, American Rock Mechanics Association , 8 pages, 2013.06.
103. GUANGQI CHEN, Zheng Lu, Yingbin Zhang, Kawakami T., Stability Analysis of Breakwater Under Seepage Flow Using DDA, ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering, Nante, France, 10.1115/OMAE2013-11605, 6, 2013.06.
104. B. Wang, K. Zen, Guangqi Chen, Y. B. Zhang, Kiyonobu Kasama, Excess pore pressure dissipation and solidification after liquefaction of saturated sand deposits, Soil Dynamics and Earthquake Engineering, 10.1016/j.soildyn.2013.02.018, 49, 157-164, 2013.06, To understand the post-liquefaction behavior of liquefied ground, it is important to get a better understanding and a more suitable characterization of the variation of excess pore pressure after liquefaction. In this paper, the soil permeability is considered as one of the key soil parameters for clarifying the mechanism of post-liquefaction behavior of liquefied ground. For this reason, a series of shaking table tests were conducted for a Toyoura sand deposit with different soil permeability values. Polymer fluid was used in model tests to vary the permeability of sand deposits. Excess pore pressures and settlements were measured in each test. A basic mechanism in post-liquefaction behavior and the solidification phenomenon after liquefaction were discussed based on these test results. Also, a new method for predicting the dissipation of excess pore pressure was developed. This study provides evidence of the important effect of soil permeability on the velocity with which the solidification front moves upward in liquefied ground. It is suggested that the value of coefficient of permeability of liquefied sand can increase to about 4.0 times the initial value. This variation of permeability after liquefaction should be taken into account in post-liquefaction analysis..
105. Jian Wu, Guangqi Chen, Lu Zheng, Yingbin Zhang, GIS-based numerical simulation of Amamioshima debris flow in Japan, Frontiers of Structural and Civil Engineering, 10.1007/s11709-013-0198-6, 7, 2, 206-214, 2013.06, Debris flow is a rapid flow which could lead to severe flooding with catastrophic consequences such as damage to properties and loss of human lives. It is important to study the movement of debris flow. Since during a debris flow process, the erosion and deposition processes are important, the no entrainment assumption is not acceptable. In this study, first we considered the debris flow as equivalent fluid and adopted the depth-averaged govern equations to simulate the movements and evolution of river bed. Secondly, the set of partial differential equations was solved numerically by means of explicit staggered leap-frog scheme that is accurate in space and time. The grid of difference scheme was derived from GIS raster data. Then the simulation results can be displayed by GIS and easily used to form the hazard maps. Finally, the numerical model coupled with GIS is applied to simulate the debris flow occurred on Oct. 20th, 2010, in Amamioshima City, Japan. The simulation reproduces the movement, erosion and deposition. The results are shown to be consistent with the field investigation..
106. GUANGQI CHEN, Yange Li, Yingbin Zhang, Jian Wu, Earthquake induced disaster chains, 5th Japan-China Geotechnical Symposium, Chengdu, China, 2013.05.
107. GUANGQI CHEN, Lu Zheng, Yingbin Zhang, Jian Wu, Numerical Simulation in Rockfall Analysis: A Close Comparison of 2-D and 3-D DDA, Rock Mechanics and Rock Engineering, 10.1007/s00603-012-0360-9, 46, 3, 527-541, 2013.05, Accurate estimation of rockfall trajectory and motion behaviors is essential for rockfall risk assessment and the design and performance evaluation of preventive structures. Numerical simulation using discontinuous deformation analysis (DDA) is effective and helpful in rockfall analysis. Up to now, there have been many reports on application of two-dimensional (2-D) DDA programs. In this paper, the major advantages of rockfall analysis using 2-D and extensions to three-dimensional (3-D) analysis are presented. A practical 3-D DDA code is demonstrated to be capable of simulating free falling, rolling, sliding, and bouncing with high accuracy. Because rockfall trajectories and motion behaviors can be described as combinations of these four types, this demonstration indicates that the implemented code is capable of providing reliable rockfall analysis. Finally, specific tests are conducted to compare 2-D and 3-D DDA rockfall analysis in
predicting trajectory and dynamic behavior. The results indicate that 3-D DDA simulations are more appropriate for rough tree-laden inclined slopes in providing detailed spatial distribution, whereas 2-D DDA simulations have better efficiency for slopes dominated by valleys and ravines. These results can help in selecting the appropriate DDA simulation for rockfall analysis..
108. Yingbin Zhang, GUANGQI CHEN, Lu Zheng, Yange Li, Xiaoying Zhuang, Effects of geometries on three-dimensional slope stability, Canadian Geotechnical Journal, 10.1139/cgj-2012-0279, 50, 3, 233-249, 2013.03, This paper analyzes the effects of complex geometries on three-dimensional (3D) slope stability using an elastoplastic
finite difference method (FDM) with a strength reduction technique. A series of special 3D slopes with various geometric
configurations, including curving slope surface, turning corners, turning arcs, and turning forms, is presented in terms of factor
of safety, shear slip surface, and deformed mesh. More than 180 cases with various geometries for different slope gradient (90°,
45°, and 26.57°) under different boundary conditions (smooth–smooth, rough–smooth, and rough–rough) are calculated and
discussed in detail. Many interesting results are obtained and some of them appear to be surprising. These results can be used
directly to offer suggestions for landslide hazard preparedness or safe and economical design of infrastructures, e.g., excavations,
embankments, and so on..
109. Yange Li, Guangqi Chen, Bo Wang, Lu Zheng, Yingbin Zhang, Chuan Tang, A new approach of combining aerial photography with satellite imagery for landslide detection, Natural Hazards, 10.1007/s11069-012-0505-x, 66, 2, 649-669, 2013.01, Subsequent rainfall after a strong earthquake can easily trigger landslides. Aerial photography is always available after a strong earthquake but not always available in a timely manner after a subsequent rainfall following the earthquake. Sometimes, only panchromatic imagery is available because of its relatively low cost and large cover capacity. To detect multi-temporal landslides induced by earthquake and its post long-term effect, in company of other factors such as subsequent rainfall, traditionally, it needs to carry out image classification multi-times to calculate the variance information. Therefore, the accuracy will be affected by accumulated errors from multi-classification, and the process is very time-consuming. In this paper, a new semi-automatic approach combing aerial photograph with satellite imagery was proposed for rapid mapping of multi-temporal landslides. The approach can enhance the change information of each landslide event in one detection process. In addition, slope units were introduced to separate the detected conjoint landslides. Chenjiaba area, which located in the highest seismic intensity zone of Wenchuan earthquake in Beichuan, China, and had a strong rainfall 4 months later, was selected as a case study to demonstrate the usefulness of this methodology. Accuracy assessment was carried out by comparing those extracted ones with a manually prepared landslide inventory map. Correctly detected were 90. 1 and 94. 2 % for earthquake-induced landslides and new landslides, respectively. Results show that this approach is capable of mapping different temporal landslides efficiently and quickly..
110. Guangqi Chen, Yange Li, Yingbin Zhang, Jian Wu, Earthquake induced geo-disaster chain, 5th China-Japan Geotechnical Symposium: New Advances in Geotechnical Engineering 5th China-Japan Geotechnical Symposium, 82-90, 2013.01, A strong earthquake can cause a large number of landslides and avalanches, which can initiate causal geo-disaster chains. A representative ring in disaster chain is that a coseismic landslide can block a river and form a landslide dam, which may burst and cause a catastrophic flood. In order to disclose the serious impacts of the geo-disaster chain induced by earthquake, this paper presented the form process of geo-disaster chain and proposed some cutting measures. According to the developing process, the geo-disaster chain from the 2008 Wenchuan earthquake was discussed. Two measures for cutting the chain are proposed, one is the landslide hazard map constructing on susceptibility analysis and the other is numerical simulation of debris flows for assessment of dangerous zone. The results of this study can help the authority make the right decision rapidly to take appropriate counter measures to reduce the risk of the geo-disaster chain or cut it directly..
111. Yange Li, GUANGQI CHEN, Bo Wang, Lu Zheng, Yingbin Zhang, Chuan Tang, A New Approach for Semi-Automatic Landslide Detection Combined by Remote Sensing and GIS Technology., Natural Hazards, 10.1007/s11069-012-0505-x, 2012.11, 66, 2, 649-669, 2012.11, A multi-temporal landslide inventory is the most basic element to better assess the co-seismic to post long term effects of strong earthquakes on slopes. In addition, quick detection of new slope failures is very helpful for relief and rescue works after each landslide disaster event. However, traditional mapping approaches are affected by the accumulated error by multiple event-based classifications and time consuming. In this paper, a new semi-automatic approach is proposed for rapid mapping of multi-temporal landslides. First, the variance information of each landslides event was assessed by image fusion technique. Second, the fusion image was semi-automatically interpreted. Third, the extracted conjoint landslides were separated by slope units. Chenjiaba area, which located in highest seismic intensity zone of Wenchuan earthquake in Beichuan, China and had a strong rainfall four months later, was selected as a case study to demonstrate the usefulness of this methodology. Accuracy assessment was carried out by comparing those extracted ones with a manually prepared landslide inventory map. Correctly detected were 90.1% and 94.2% for earthquake-induced landslides and rainfall-induced landslides respectively. Results show that this approach is capable of mapping different temporal landslides efficiently and quickly..
112. GUANGQI CHEN, Yange Li, Yingbin Zhang, Jian Wu, The disaster chain of earthquake induced landslides, International Symposium on Earthquake-induced Landslides (IS-Kiryu), Kiryu, Japan, 947-956, 2012.11.
113. Yingbin Zhang, GUANGQI CHEN, Lu Zheng, Yange Li, Numerical analysis of the largest landslide induced by the Wenchuan earthquake, May 12, 2008 using DDA, International Symposium on Earthquake-induced Landslides (IS-Kiryu), Kiryu, Japan, 615-624, 2012.11.
114. Yingbin Zhang, GUANGQI CHEN, Kiyonobu KASAMA, Yange Li, Newmark sliding displacement induced by severe near-fault ground motion, International Joint Symposium on Urban Geotechnics for Sustainable Development, Suwon, Korea, 2012.11.
115. Yanqiang Wu, GUANGQI CHEN, Zaisen Jiang, L. Zhang, X. Liu, The Algorithm of Simplex Integration in Three-Dimension and Its Characteristic Analysis, International Journal of Advancements in Computing Technology, 4, 10, 246-256, 2012.10.
116. GUANGQI CHEN, Rockfall Analysis Using 3D DDA Simulation, The 1st Workshop of ISRM DDA Commission, Seoul, Korea, 2012.10.
117. L. Zheng, G. Chen, K. Kasama, Y. Li and Y. Zhang, Rockfall simulation with consideration of multi-blocks using 3D DDA and its application to countermeasures, Proceedings of 7th Asian Rock Mechanics Symposium (ARMS7), Seoul, Korea, 2012.10.
118. Li Yange, GUANGQI CHEN, Rainfall and earthquake-induced landslides susceptibility assessment using GIS and Artificial Neural Network, the European Geosciences Union, 10.5194/nhess-12-2719-2012, 12, 2719-2729, 2012.08, A GIS-based method for the assessment of landslide susceptibility in a selected area of Qingchuan County in China is proposed by using the back-propagation Artificial Neural Network model (ANN). Landslide inventory was derived from field investigation and aerial photo interpretation. 473 landslides occurred before the Wenchuan earthquake (which were thought as rainfall-induced landslides (RIL) in this study), and 885 earthquake-induced landslides (EIL) were recorded into the landslide inventory map. To understand the different impacts of rainfall and earthquake on landslide occurrence, we first compared the variations between landslide spatial distribution and conditioning factors. Then, we compared the weight variation of each conditioning factor derived by adjusting ANN structure and factors combination respectively. Last, the weight of each factor derived from the best prediction model was applied to the entire study area to produce landslide susceptibility maps..
119. J. Wu, G. Chen, K. Kasama, L. Zheng and Y. Zhang, GIS-based numerical simulation of debris flow, Proceedings of The world congress on advances in civil, environmental, and materials research (ACEM'12), Seoul, Korea, 2012.08.
120. G. Samodra, G. Chen, J. Sartohadi, K. Kasama and D. Hadmoko, Spatial pattern of Socio-economic landslide vulnerability and its spatial prediction by means of GIS-Fuzzy Logic in Kayangan Catchment, Indonesia, Proceedings of The 8th Annual Conference of International Institute for Infrastructure, Renewal and Reconstruction. Kumamoto, Japan, 520 - 529, 2012.08.
121. Y. Fan, G. Chen and K. Kasama, Geographical information analysis on the causes of collapse initiation in Tohoku Earthquake, Proceedings of The 8th Annual Conference of International Institute for Infrastructure, Renewal and Reconstruction. Kumamoto, Japan, 548 - 557, 2012.08.
122. Y. Zhang, G. Chen, L. Zheng, J. Wu and X. Zhuang, Effects of vertical seismic force on the initiation of the Daguangbao landslide induced by the Wenchuan earthquake, Proceedings of The 8th Annual Conference of International Institute for Infrastructure, Renewal and Reconstruction. Kumamoto, Japan, 530 - 539, 2012.08.
123. J. Wu, G. Chen, Y. Zhang and C. Tang, Application of back-propagation networks in debris flow runout estimation in the Wenchuan earthquake area, Proceedings of The 8th Annual Conference of International Institute for Infrastructure, Renewal and Reconstruction. Kumamoto, Japan, 512 - 519, 2012.08.
124. T.-K. Nian, C. Liu, GUANGQI CHEN, et al., Numerical analysis of stability and creep-deformation of complex embankment using non-convergence criterion, Journal of Convergence Information Technology-An International Journal, 7, 17, 164-175, 2012.07.
125. Y. Zhang, G. Chen, J. Wu, L. Zheng and X. Zhuang, Numerical simulation of seismic slope stability analysis based on tension-shear failure mechanism, Geotechnical Engineering, 43, 18 - 28, 2012.06.
126. B. Wang, G. Chen, K. Kasama and Y. Li, Experimental studies of liquefaction-induced ground deformation with different sand permeability, Proceedings of the 46th U.S. Rock Mechanics and Geomechanics Symposium, Chicago, USA, 2012.06.
127. G. Chen, L. Zheng and Z. Jiang, Comparison of 2D and 3D DDA in rockfall analysis, Proceedings of the 46th U.S. Rock Mechanics and Geomechanics Symposium, Chicago, USA, 2012.06.
128. Y. Li, G. Chen, C. Tang, L. Zheng and B. Wang, Automatic Detection of Landslides Induced by the Wenchuan Earthquake and Subsequent Rainstorm, Proceedings of the 46th U.S. Rock Mechanics and Geomechanics Symposium, Chicago, USA, 2012.06.
129. Li Yange, GUANGQI CHEN, An approach from earthquake-induced landslides identification to numerical simulation of debris flow, Memoirs of the Faculty of Engineering, Kyushu University, 72, 2, 69 - 83, 2012.06.
130. T.-K. Nian, R.-Q. Huang, S.-S. Wan, GUANGQI CHEN, Three-dimensional strength-reduction finite element analysis of slopes: geometric effects, Canadian Geotechnical Journal, 10.1139/T2012-014, 49, 5, 574-588, 2012.05.
131. GUANGQI CHEN, Application of GEOBIA-Multinomial logistic regression for landslide vulnerability assessment in Kayangan Catchment, Indonesia, Proceedings of International Conference on Geographic Object Based Image Analysis, 4. (GEOBIA), 13 -19, 2012.05.
132. L. Zheng, G. Chen, K. Zen and K. Kasama, Numerical validation of Multiplex Acceleration Model for earthquake induced landslides, Geomechanics and Engineering, 4, 1, 39 -53, 2012.03.
133. Y. Zhang, G. Chen, K. Zen, K. Kasama, J. Wu and L. Zheng, Seismic slope stability analysis subjected to tension failure, 自然災害研究協議会西部地区部会報, 36, 21 - 24, 2012.02.
134. J. Wu, G. Chen, K. Zen, K. Kasama, L. Zheng and Y. Zhang, GIS-based two-dimensional numerical simulation of debris flow in mobile-bed gully, 自然災害研究協議会西部地区部会報, 36, 17 - 20, 2012.02.
135. G. Samodra, G. Chen, J. Sartohadi and K. Kasama, Comparison of weight of evidence and logistic regression for medium scale landslide susceptibility mapping in Yogyakarta Region Indonesia, 自然災害研究協議会西部地区部会報, 36, 25 - 28, 2012.02.
136. C. Tang, T.W.J. van Asch, M. Chang, G. Chen, X. Zhao and X. Huang, Catastrophic debris flows on 13 August 2010 in the Qingping area, southwestern China: The combined effects of a strong earthquake and subsequent rainstorms, Geomorphology, 139, 559 -576, 2012.02.
137. G. Chen, Z. Jiang and Y. Wu, A New Approach for Numerical Manifold Method, Journal of Adaptive & Dynamic Computing, 2012.02.
138. Y. Wu, Guangqi Chen, Z. Jiang, Q. Li, W. Wei, X. Liu and J. Zhao, Research on 3 dimension manifold method and its application, Proceedings of the 10th International Conference on Analysis of Discontinuous Deformation, Hawaii, USA, 281-286, 2011.12.
139. L. Zheng, Guangqi Chen, Kouki Zen and Kiyonobu Kasama, The method of slope modelling for rockfall analysis using 3D DDA, Proceedings of the 10th International Conference on Analysis of Discontinuous Deformation, Hawaii, USA, 189-194, 2011.12.
140. Y. Li, G. Chen, C. Tang and L. Zheng, A debris flow and its risk analysis related to the 2008 Wenchuan earthquake, GEOMAT2011, Geotechnique, Construction, Materials & Enviroment, 1, 479-484, 2011.12.
141. Yasuhara,K.,Komine, H., Yokoki, H., Suzuki, T., Mimura, N., Tamura, M. and Chen, G., Effects of climate change on geo-disasters in coastal zones and their adaptation, Journal of Geotextiles and Geomembranes, 30, 24-34, 2011.12.
142. Yuka YAMASHITA, Kiyonobu KASAMA, Kouki ZEN and Guangqi CHEN, Dehydration and Strength Properties of Cement-mixed and Dehydrated Clay, Proceedings of the International Conference on Advances in Geotechnical Engineering (ICAGE 2011), 151-155, 2011.11.
143. Yutaro INATOMI, Kiyonobu KASAMA, Kouki ZEN and Guangqi CHEN, Effects of Percent Defective on the Liquefaction Risk of Anti-liquefaction Ground, Proceedings of the International Conference on Advances in Geotechnical Engineering (ICAGE 2011), 791-796, 2011.11.
144. Yingbin Zhang, Guangqi Chen, Kouki Zen and Kiyonobu Kasama, High-speed Starting Mechanism of Rock Avalanches Induced by Earthquake, Proceedings of the International Conference on Advances in Geotechnical Engineering (ICAGE 2011), 803-809, 2011.11.
145. Nian Tingkai, Guangqi Chen and Maotian Luan, Strength reduction limit analysis approach of slope-pile system subjected to pore-water pressure and seismic force, Proceedings of International Symposium on Advaced Technology of Preventive Measures against Landslides Fukuoka 2011, 109-115, 2011.11.
146. Yange Li, Guangqi Chen, Kouki Zen and Kiyonobu Kasama, Application of remote sensing and GIS technique to landslide analysis, Proceedings of International Symposium on Advaced Technology of Preventive Measures against Landslides Fukuoka 2011, 140-146, 2011.11.
147. Yingbin Zhang, Guangqi Chen, Kouki Zen and Kiyonobu Kasama, Seismic stability analysis of multi-orientational anchored rock slope subjected to surcharge, ground water by the limit analysis method, Proceedings of International Symposium on Advaced Technology of Preventive Measures against Landslides Fukuoka 2011, 191-197, 2011.11.
148. Yingbin Zhang, Guangqi Chen, Kouki Zen and Kiyonobu Kasama, Limit analysis of seismic slope stability based on tension-shear failure mechanism, Proceedings of the International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Vancouver, Canada, CDROM, 2011.09.
149. Simeng Dong, Kouki Zen, Guangqi Chen and Kiyonobu Kasama, Temporal Spatial Response Between Caisson Breakwater and Seabed Caused by Wave Induced Liquefaction, Proceedings of International Conference on Coastal Structures 2011, CDROM, 2011.09.
150. Bo Wang, Kouki Zen, Guangqi Chen and Kiyonobu Kasama, Effect of permeability on liquefaction-induced lateral flow, Proceedings of International Conference on Coastal Structures 2011, CDROM, 2011.09.
151. K. Yasuhara, H. Komine, H. Yokoki, T. Suzuki, N. Mimura, M. Tamura and G. Chen, Effects of climate change on coastal disasters: new methodologies and recent results, Sustainability Science, 6, 219-232, 2011.09.
152. Zusong Wu, Guangqi Chen, Kouki Zen, Kiyonobu Kasama and Daoliang Wang, Effect of Blasting on the Adjacent Underground Tunnels, Applied Mechanics and Materials, 92, 1870-1878, 2011.08.
153. T. K. Nian, K. L. Zhang, R. Q. Huang and G. Q. Chen, Stability Analysis of a 3D Vertical Slope with Transverse Earthquake Load and Surcharge, Applied Mechanics and Materials, 91, 676-679, 2011.07.
154. G. Chen, K. Zen, L. Zheng and Y. Tsusue, Assessing validity of landslide preventive structure by DDA simulations, Proceedings of the 45th U.S. Rock Mechanics and Geomechanics Symposium, CDROM, ARMA 11-280, 2011.06.
155. G. Chen, Z. Jiang and Y. Wu, Numerical manifold method with fixed mesh, Proceedings of the 45th U.S. Rock Mechanics and Geomechanics Symposium, CDROM, ARMA 11-281, 2011.06.
156. Zusong Wu, Guangqi Chen, Kouki Zen and Xinrong Liu, The Slabbing Mechanics Analysis of the Tunnel Lining, Advanced Materials Research, 246, 3530-3537, 2011.06.
157. G. Chen, K. Zen and Y.Okubo, Stability analysis of rainfall induced shallow landslides, Proceedings of the 14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, Hong Kong, 2011.05.
158. Junjie Sun, Lanmin Wang and Guangqi Chen, A probabilistic method to assess the regional susceptibility of landslides induced by earthquake in Kitakyushu City, Japan, Disaster Advances, 4, 1, 7-18, 2011.01.
159. Seismic Bearing Capacity of Artificially Solidified Ground by the Random Field Numerical Limit Analyses.
160. Effects of Water-cement Ratio on the Unconfined Compressive Strength of Cement-mixed and Dehydrated Clays.
161. Strength Property of Large Soil-block by Cement Mixing and Mechanical Dehydration.
162. Guangqi Chen, Lu Zheng, and Kouki Zen, A comparison between DDA and DEM in numerical simulations of earthquake induced landslides, Geomechanics and Geotechnics: From Micro to Macro, 551-557, 2010.10.
163. Residual shear behavior of serpentinite in Shiraishi landslide, Tokushima Prefecture and sliding mechanism.
164. Masaki SANO, Kouki ZEN, Guangqi CHEN and Kiyonobu KASAMA, Effects of Physical Property on the Unconfined Compressive Strength of Cement-Mixed and Dehydrated Clay, The 7th International Symposium on Lowland Technology (ISLT 2010), 70-73, 2010.09.
165. Yuka YAMASHITA, Kouki ZEN, Guangqi CHEN and Kiyonobu KASAMA, Scale-up Test for Producing High-strength Clay by Cement Mixing and Mechanical Dehydration, The 7th International Symposium on Lowland Technology (ISLT 2010), 74-78, 2010.09.
166. K.Yasuhara, H. Komine, S. Murakami, G. Chen , Y. Mitani, D.M. Duc, Effects of climate change on geo-disasters in coastal zones and their adaption, Journal of Geotextiles and Geomembranes, 29, 4, 2010.08.
167. G. Wang, T. Kamai, R. Huang, G. CHEN, F. Du, W. Zhang, A large landslide triggering by the 2008 Wenchuan (M8.0) earthquake: insights of seismic motion, Proceedings of the 11th Congress of the International Association for Engineering Geology and the Environment (IAEG), 757-764, 2010.07.
168. Shaking table test on the dynamic property of solidified ground considering the spatial locality of liquefaction.
169. G. Chen, K. Zen, L. Zheng and Z. Jiang, A new model for long-distance movement of earthquake induced landslide, Proceedings of the 44th U.S. Rock Mechanics and Geomechanics Symposium,  U.S.A, CDROM ARMA 10-297, 2010.06.
170. GUANGQI CHEN , LU ZHENG, KOUKI ZEN and ZAISHENG JIANG, BEHAVIOR OF DDA IN THE SIMULATION OF BLOCK COLLISION FOR EARTHQUAKE INDUCED LANDSLIDE, Recent Developments of Geotechnical Engineering, 572-577, 2010.04.
171. 安原一哉、小峯秀雄、村上 哲、陳 光斉、三谷泰浩、田村 誠, 温暖化による気候変動が地盤災害に及ぼす影響と適応策, 第24回環境工学連合講演会論文集, 85-94, 2010.04.
172. Shaking Table Model Test on Seismic Stability of Caisson Type Quay-Wall in Application of Cement-Mixing Method.
173. 地盤物性に空間的不均質性を有する固化処理地盤の液状化リスク.
174. The Effects of Mound Dimension of a Breakwater on the Mechanism of Wave-induced Liquefaction of Seabed.
175. Numerical Limit Analysis for Reliability-based Bearing Capacity of Non-Uniform Ground.
176. K.Yasuhara, H. Komine, S. Murakami, G. Chen & Y. Mitani, Effects of climate change on geo-disasters in coastal zones, Journal of Global Enviroment Engineering, Vol. 15, pp.15-23, 2010.02.
177. Kiyonobu KASAMA, Kouki ZEN and Guangqi CHEN, Shaking Table Test on the Dynamic Earth Pressure against Retaining Structure in Application of Cement-Mixing Method, Proceedings of International Symposium on Ground Improvement Technologies and Case Histories (ISGI09), pp.579-586, 2009.12.
178. Masaki SANO, Kouki ZEN, Guangqi CHEN and Kiyonobu KASAMA, Dehydration and Strength Properties of Cement-Mixed Soils with a Mechanical Dehydration, Proceedings of International Symposium on Ground Improvement Technologies and Case Histories (ISGI09), pp.483-490, 2009.12.
179. Jun KUTSUNA, Kouki ZEN, Guangqi CHEN and Kiyonobu KASAMA, Numerical Limit Analysis on the Seismic Bearing Capacity of Anti-Liquefaction Ground, Proceedings of International Symposium on Ground Improvement Technologies and Case Histories (ISGI09), pp.411-418, 2009.12.
180. Y.L. HOU, G.Q. CHEN and C.H. ZHANG, Extension of Distinct Element Method and Its Application in Fracture Analysis of Quasi-brittle Materials, Proceedings of the 9th International Conference on Analysis of Discontinuous Deformation, Singapore, pp227-236, 2009.11.
181. G. CHEN, J. SUN and K. ZEN, GIS-BASED PROBABILISTIC ANALYSIS OF THE SLOPE SAFETY FACTOR FOR LANDSLIDE HAZARD MAPPING INDUCED BY EARTHQUAKE, Proceedings of International Joint Symposium on Geodisaster prevention and Geoenvironment in Asia, pp76-83, 2009.11.
182. T. NIAN, S. WAN and G.. CHEN, 2D AND 3D SLOPE STABILITY ANALYSIS USING SHEAR STRENGTH REDUCTION FINITE ELEMENT METHOD, Proceedings of International Joint Symposium on Geodisaster prevention and Geoenvironment in Asia, pp71-75, 2009.11.
183. K. YASUHARA, H. KOMINE, S. MURAKAMI, G. CHEN, Y. MITANI, EFFECTS OF CLIMATE CHANGE ON GEO-DISASTERS IN COASTAL ZONES, Proceedings of International Joint Symposium on Geodisaster prevention and Geoenvironment in Asia, pp102-109, 2009.11.
184. Norio KATAOKA, Kouki ZEN, Guangqi CHEN, Kiyonobu KASAMA and Kentaro HAYASHI, Effects of Spatial Variability of Cement-Treated Soil on Liquefaction Potential, Proceedings of International Conference on Performance-Based Design in Earthquake Geotechnical Engineering - from case history to practice -, pp.1249-1554, 2009.06.
185. Kiyonobu KASAMA, Kouki ZEN, Guangqi CHEN, Masakazu KOBAYASHI and Kentaro HAYASHI, Shaking Table Test for Partially Improved Ground Considering the Spatial Locality of Liquefaction, Proceedings of International Conference on Performance-Based Design in Earthquake Geotechnical Engineering - from case history to practice -, pp.1161-1166,, 2009.06.
186. Guangqi CHEN,Kouki ZEN,Zaisen Jiang and Yujian Jiang, Study on Mechanism of Long-distance Movement of Debris from Landslide Induced by Earthquake, Proceedings of International Conference on Earthquake Engineering, pp648-651, 2009.05.
187. K. Kasama, K. Zen and G. Chen, SHAKING TABLE TEST ON THE SEISMIC BEHAVIOR OF CAISSON TYPE QUAYWALL IN APPLICATION OF GROUND SOLIDIFICATION TECHNIQUE, Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering, p8, CDROM: OMAE2009-79112, 2009.05.
188. Y. Tomi, K. Zen, G. Chen and K. Kasama, EFFECT OF RELATIVE DENSITY ON THE WAVE-INDUCED LIQUEFACTION IN SEABED AROUND A BREAKWATER, Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering, p7, CDROM: OMAE2009-79601, 2009.05.
189. M. Kobayashi, K. Zen, G. Chen and K. Kasama, SHAKING TABLE TEST ON THE IMPROVEMENT DIMENSION OF PERMEABLE GROUNTING METHOD FOR LIQUEFACTION CONTERMESURE, Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering, p7, CDROM: OMAE2009-79635, 2009.05.
190. Guangqi CHEN,Kouki ZEN, Study on Mechanism of High Speed & Long-distance Movement of the Debris Induced by Earthquake, Proceedings of the Second China-Japan Science Forum, pp199-200, 2009.03.
191. CHEN Guangqi, PRACTICAL TECHNIQUES FOR RISK ANALYSIS OF EARTHQUAKE-INDUCED LANDSLIDE, Chinese Journal of Rock Mechanics and Engineering, Vol.27, No.12, pp2395-2402, 2008.12.
192. ZHOU Guoyun, CHEN Guangqi, LANDSLIDE RISK PREDICTION BASED ON COUPLING GIS AND SECOND THEORY OF QUANTIFICATION, Chinese Journal of Rock Mechanics and Engineering, Vol.27, No.12, pp2494-2500, 2008.12.
193. CHEN Guangqi,ZEN Kouki,KASUYA Yuki, PRACTICAL RISK ASSESSMENT OF SLOPE DISASTER INDUCED BY EARTHQUAKE, Chinese Journal of Rock Mechanics and Engineering, Vol.27, No.12, pp2488-2493, 2008.12.
194. CHEN Guangqi,ZEN Kouki, Application of Risk Management to Slope Disaster Prevention, Proceedings of the 2nd International Symposium on Climate Change and the Sustainability, pp27-35, 2008.11.
195. MAKIKO MISUMI,KOUKI ZEN,GUANGQI CHEN and KIYONOBU KASAMA, ACCURACY EVALUATION OF SLOPE DISASTER RISK MAP AT KITA-KYUSHU CITY USING GEOGRAPHICAL INFORMATION SYSTEM, Proceedings of the 2nd International Symposium on Climate Change and the Sustainability, pp136-139, 2008.11.
196. Practical Risk Management of Slope Disaster.
197. T.K. Nian, G.Q. CHen, M.T. Luan, Q. Yang, and D.F. Zheng, Limit analysis of the stability of slopes reinforced with piles against landslide in nonhomogeneous and anisotropic soils, Canadian Geotechnical Journal, Vol.45, No.8, pp1092-1103, 2008.08.
198. G. CHEN, K. ZEN & N. Kasuya, RISK MANEGEMENT OF SLOPE DISASTER INDUCED BY EARTHQUAKE, Proceedings of the 13th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, Vol.29,  pp. 927-930, 2007.12.
199. Tomoyuki Shigeoka, Kouki Zen, Guangqi Chen, Kiyonobu Kasama, SEISMIC SETTLEMENT ESTIMATION ON PARTIALLY IMPROVED GROUND USING SHAKING TABLE, NEW FRONTIERS IN CHINESE AND JAPANESE GEOTECHNIQUES, Vol.29,  pp. 521-531, 2007.11.
200. Daisuke Irikado, Kouki Zen, Guangqi Chen, A STUDY ON EVALUATION OF LANDSLIDE RISK INDUCED BY RAINFALL WITH GEOGRAPHICAL INFORMATION SYSTEM, NEW FRONTIERS IN CHINESE AND JAPANESE GEOTECHNIQUES, Vol.29,  pp. 207-212, 2007.11.
201. T.K. Nian, M.T. Luan, Q.Yang & G. Chen, Numerical analysis of stability of slope reinforced with piles subjected to combined load, New Horizons in Earth Reinforcement, Vol.29,  pp. 401-405, 2007.11.
202. Guangqi CHEN, Kouki ZEN and Daisuke IRIKADO, Estimation of economic loss from climate-change-induced natural disasters using GIS Platform, Proceedings of international Symposium on Mitigation & Adaptation of Climate-change-induced Natural Disasters, Vol.29,  pp. 203-212, 2007.09.
203. Guangqi CHEN, A View on Manifold Method Comparing with Finite Element Method, Proceedings of International Symposium on Computational Mechanics, Vol.29,  pp. 1093-1103, 2007.07.
204. Soonbo YANG,善功企,陳光斉,笠間清伸, Analysis of the model experiment on the wave-induced pore presure, 自然災害研究協議会西部地区部会会報・研究論文集, Vol.31、 pp.129-132, 2007.02.
205. Guangqi Chen, Kouki Zen、Hideo Nagase、 Kenichi Sato、Kiyoshi Omine、Taizou Kobayashi、Hidefumi Sato, Investigation and Restoration Countermeasure Work for the Slope Disaster Induced by the 2005 West off Fukuoka Earthquake, SOILS AND FOUNDATIONS, Vol.46, No.6、777−791, 2006.12.
206. Hideo Nagase、Kouki Zen、 Akihiko Hirooka、Noriyuki Yasufuku、Kiyunobu Kasama, Taizou Kobayashi, Guangqi Chen, ZONING FOR LIQUEFACTION AND DAMAGE TO PORT AND HARBOR FACILITIES AND OTHERS DURING THE 2005 FUKUOKA FUKUOKA-KEN SEIHO SEIHO-OKI EARTHQUAKE, SOILS AND FOUNDATIONS, Vol.46, No.6、805−816, 2006.12.
207. Taizou Kobayashi, Kouki Zen, Noriyuki Yasufuku, Hideo Nagase, Guangqi Chen, Kiyonobu Kasama,Akihiko Hirooka, Hiromu Wada, Yuji OnoYama and Hiroshi Uchida, Damage to Residential Retaining Walls at the Genkai-Jima Island Induced by the 2005 Fukuoka-Ken Seiho-Oki Earthquake, SOILS AND FOUNDATIONS, Vol.46, No.6、793-804, 2006.12.
208. Kouki Zen, Guangqi Chen, Kiyonobu Kasama, Kiichiro Kuratomi, Elution Characteristics of Pollutants in Cement-Mixed and Dehydrated Contaminated Sediment, RECENT DEVELOPMENT OF GEOTECHNICAL AND GEO-ENVIRONMENTAL ENGINEERING IN ASIA, 337-342, 2006.11.
209. Takeshi Fujinami, Guangqi Chen, Kouki Zen, Kiyonobu Kasama, An Attempt to Estimate Economic Loss Caused by Typhoon Considering Global Warming, RECENT DEVELOPMENT OF GEOTECHNICAL AND GEO-ENVIRONMENTAL ENGINEERING IN ASIA, 435-440, 2006.11.
210. Kiyonobu Kasama, Kouki Zen, Guangqi Chen, Liquefaction Potential Evaluation for Cement-Treated Sandy Ground, RECENT DEVELOPMENT OF GEOTECHNICAL AND GEO-ENVIRONMENTAL ENGINEERING IN ASIA, 397-402, 2006.11.
211. Hideo Nagase、Kouki Zen、 Akihiko Hirooka、Noriyuki Yasufuku、Kiyunobu Kasama, Taizou Kobayashi, Guangqi Chen, Zoning for liquefaction and structural damage during the 2005 Fukuoka-Ken Seiho-Oki earthquake, RECENT DEVELOPMENT OF GEOTECHNICAL AND GEO-ENVIRONMENTAL ENGINEERING IN ASIA, 40249, 2006.11.
212. Guangqi Chen, Kouki Zen, Shu Moriyama, Risk Analysis of Slope Disasters in a Large Area Using GIS Platform, RECENT DEVELOPMENT OF GEOTECHNICAL AND GEO-ENVIRONMENTAL ENGINEERING IN ASIA, 269-274, 2006.11.
213. Statistical Consideration of the Amount of Disaster Damage by a Typhoon in Kyushu Region.
214. Report for Geotechnical Disaster in Oita Caused by Typhoon No.14 in 2005.