Application of the material point method to simulate the post-failure runout processes of the Wangjiayan landslide

• MPM is used to simulate post-failure runout and deposit process of Wangjiayan landslide.
• Kinematic behaviors of landslide are investigated in displacement, velocity, plastic strain, and deposition.
• The effects of buildings on landslide kinematics and deposition are significant.

The first part of the paper presents a brief description of the material point method (MPM) including the governing equations, solution scheme and a benchmark problem of soil collapse simulated using the method. In the second and third part of the paper, the post-failure runout process of the Wangjiayan landslide is simulated and analyzed. The landslide's final topography and information from post-failure in-situ survey and laboratory tests are used to constrain the accuracy of computational results. The kinematic behaviors of the failure mass are investigated in terms of displacement, velocity, effective plastic strain fields and topography changes during the movement. Comparisons are made between conditions with and without buildings on the deposition area. Numerical computations demonstrate that the presence of buildings on the sliding path strongly governs the flow regime, run-out distance, velocity, strain field and final deposition topography of the landslide. So it is very essential to incorporate the effects of buildings in the modelling and analyses. Numerical results considering buildings show that the slide lasts about 30 s with the most rapid phase occurring between 6 and 12 s, and that the maximum simulated velocity among the sliding particles in the landslide is 43.5 m/s, indicates that the moving of the landslide mass was very fast. The run-out distance simulated with MPM matches the measured post-earthquake topography well, whereas the shape of the simulated deposition zone is a little differs. The buildings influence the sliding by shortening the overall run-out distance, decelerating the movement of the bottom layer, and increasing the internal deformation and mixing among deposition layers.