A hybrid contact approach for modeling soil-structure interaction using the material point method

The grid-based multi-velocity field technique has become increasingly popular for simulating the Material Point Method (MPM) in contact problems. However, this traditional technique has some shortcomings, such as (1) early contact and contact penetration can occur when the contact conditions are unsuitable, and (2) the method is not available for contact problems involving rigid-nonrigid materials, which can cause numerical instability. This study presents a new hybrid contact approach for the MPM to address these limitations to simulate the soil and structure interactions. The approach combines the advantages of point-point and point-segment contacts to implement contact detection, satisfying the impenetrability condition and smoothing the corner contact problem. The proposed approach is first validated through a disk test on an inclined slope. Then, several typical cases, such as granular collapse, bearing capacity, and deformation of a flexible retaining wall, are simulated to demonstrate the robustness of the proposed approach compared with FEM or analytical solutions. Finally, the proposed method is used to simulate the impact of sand flow on a deformable structure. The results show that the proposed contact approach can well describe the phenomenon of soil-structure interaction problems.