15:30 〜 17:00
[HDS05-P17] Dynamic Analysis of Soil-Rock Mixture (SRM) Landslide Using the Coupled DDA-SPH Method
キーワード：地すべり、数値計算法、動的シミュレーション、斜面安定解析
Population growth and human activities have brought significant environmental challenges and increased natural events such as landslides. Landslides occur frequently throughout the world and can result in massive damage and casualties. Soil-rock mixture (SRM), which is mainly composed of rock blocks and fine soil, is widely distributed in nature, especially in mountainous areas. Therefore, it is necessary to study the mechanical behaviors of SRM for the prediction and mitigation of landslide disasters, which is still a challenging issue. However, it is very difficult to apply the traditional testing method to the investigation of SRM on account of the limitations of testing techniques. Thanks to advances in computer technology, computational approaches to the stability analysis of SRM slope are playing an increasingly important role, both in theory and practice.
A single numerical method is usually applied to solve problems involving one or two phases. Some researchers have devoted their efforts to coupling various numerical methods in order to broaden the applications of numerical methods. Among them, DDA is a promising technique for simulating problems composed of blocky systems, such as rock falls, fractures, landslides, and others. As a member of the family of the discrete element method, DDA has the advantage of simulating arbitrary-shaped rocks and large deformation problems. On the other hand, SPH is one of the most popular numerical methods for analyzing the mechanical behaviors of flow-like materials and has been extended to simulate soil by implementing proper constitutive models. In this study, the coupling procedure of the coupled DDA-SPH method is modified, and the application of this method is extended to the slope stability analysis and the post-failure analysis of SRM slopes to investigate the behaviors of SRM slopes. First, the soil constitutive model in the soil-particle-based SPH is improved by implementing a pension damage model. The effectiveness of the Brazilian disc model has been demonstrated. Second, the contact algorithm is modified by adding tensile springs at the interfaces between the SPH particle and the edge of the DDA block. The determination of the contact spring stiffness is presented, and the accuracy of the contact force is verified. After these improvements and modifications, the tensile behavior of the SRM slope can be investigated. Then, the effect of the interface tensile strength is clarified using the proposed method. An SRM slope toppling model is presented and simulated using the modified DDA-SPH coupled method. The result suggests that the weak interface strength could more likely lead to tensile failure at interfaces, which could further cause toppling and collapse of the SRM slope. The safety factor of the SEM slope increased nearly linearly with the increase in the interface tensile strength until it reached an upper limit. Then, the effect of the rock content in SRM slopes on the impact force on buildings is studied through several numerical slope models with different rock contents. It is found that the impact force on nearby buildings increases with increasing rock content.
A single numerical method is usually applied to solve problems involving one or two phases. Some researchers have devoted their efforts to coupling various numerical methods in order to broaden the applications of numerical methods. Among them, DDA is a promising technique for simulating problems composed of blocky systems, such as rock falls, fractures, landslides, and others. As a member of the family of the discrete element method, DDA has the advantage of simulating arbitrary-shaped rocks and large deformation problems. On the other hand, SPH is one of the most popular numerical methods for analyzing the mechanical behaviors of flow-like materials and has been extended to simulate soil by implementing proper constitutive models. In this study, the coupling procedure of the coupled DDA-SPH method is modified, and the application of this method is extended to the slope stability analysis and the post-failure analysis of SRM slopes to investigate the behaviors of SRM slopes. First, the soil constitutive model in the soil-particle-based SPH is improved by implementing a pension damage model. The effectiveness of the Brazilian disc model has been demonstrated. Second, the contact algorithm is modified by adding tensile springs at the interfaces between the SPH particle and the edge of the DDA block. The determination of the contact spring stiffness is presented, and the accuracy of the contact force is verified. After these improvements and modifications, the tensile behavior of the SRM slope can be investigated. Then, the effect of the interface tensile strength is clarified using the proposed method. An SRM slope toppling model is presented and simulated using the modified DDA-SPH coupled method. The result suggests that the weak interface strength could more likely lead to tensile failure at interfaces, which could further cause toppling and collapse of the SRM slope. The safety factor of the SEM slope increased nearly linearly with the increase in the interface tensile strength until it reached an upper limit. Then, the effect of the rock content in SRM slopes on the impact force on buildings is studied through several numerical slope models with different rock contents. It is found that the impact force on nearby buildings increases with increasing rock content.