Random generation of the meso-structure of a soil-rock mixture and its application in the study of the mechanical behavior in a landslide dam

• A 2D random generation program of the meso-structure of (S-RM) based on random polygonal rock blocks has been developed;
• A new multi-circle representation method of polygonal blocks has been developed;
• A DEM biaxial test method with a flexible confining stress boundary has also been developed;
• The meso parameters of the soil and rock blocks have been obtained from laboratory and DEM numerical tests;
• The shear strength, failure process and formation mechanism of shear zones in (S-RM) have been studied.

A discrete element method (DEM) numerical simulation is used as a tool to study the mechanical behavior of soil-rock mixtures (S-RM) in a landslide dam. A 2D random generation program (R-SRM2D) of the meso-structure of (S-RM) based on random polygonal rock blocks has been developed, and is used to generate the (S-RM) numerical model of the study area. A new multi-circle representation method of polygonal blocks has been developed, which can better model the mechanical properties and failure process of rock blocks. A DEM biaxial test method with a flexible confining stress boundary has also been developed, which can better model the side boundary conditions of the sample. The meso-parameters of the circular particles representing the soil and rock blocks of the (S-RM) have been obtained from laboratory tests and DEM numerical simulations of soil and rock samples. Based on the meso-parameters, a series of biaxial tests of (S-RM) sample have been conducted using the DEM numerical method. The shear strength, failure process and formation mechanism of shear zones in (S-RM) have been studied. With the increase of the confining stress, the rock blocks in or near the shear zones will be broken, changing the shape of the shear zones, and leads to the shear strength of the (S-RM) sample showing nonlinear characteristics. Furthermore, the strength envelope of (S-RM) sample can be fitted through a power law function in the p-q plane.