Rainfall Boundary Condition in a Multiphase Material Point Method

The Material Point Method (MPM) is an emerging computational tool to simulate the complex dynamic process of rainfall-induced landslide. In this field, hydraulic boundary conditions play an important role. In recent researches, the average relative velocity of pore water with respect to the solid skeleton is considered as Darcy’s velocity usually. Hence, rainfall intensity (mm/h) can be assigned to the node of the mesh as a velocity boundary directly. However, the evolution of true velocities of liquid and solid phases has missed so far in the investigation of the landslide process. In order to keep the information of true velocities in the simulation, this paper provided a new solution to estimate the true velocity of the liquid phase at the node of the boundary layer and has been implemented a coupled hydro-mechanical model using MPM. The validation of such implementation was achieved by simulating a 1D infiltration problem and comparing with the MPM results with those obtained through the commercial software PLAXIS. With the help of this newly implemented boundary condition, rainfall-induced landslides can be better investigated using MPM.