## 1 Introduction
The other is to use the discrete element method (DEM) to analyze the Micro-Mechanical Properties of SRM [9; 15; 16; 17] carried out a two-dimensional particle flow simulation of soil-rock mixture near the foundation of a dam by biaxial test and direct shear test and analyzed the influence laws of rock content, shape of block stone, and confining pressure. Non-homogeneous slopes are more widely distributed in nature than homogeneous soil slopes. Moreover, one of the most representative of these is the SRM slope [18; 19], which consists of stones and soils with comprehensively varying properties (in this study, the effect of water is not considered). The traditional assumption of homogeneous slopes always leads to erroneous results in the solution of such problems. At present, research on SRM slope mainly includes on-site geological investigation [20], indoor experiments [21], numerical simulation [3; 4; 15; 22] and so on. With the development of computer technology and the advantages of numerical simulation, such as low cost and high repeatability, computer simulation has gradually become an integral part of geotechnical engineering research. It has remained a research hotspot in the field. Current numerical simulations of SRM are more concerned with their stability and small-scale model tests to determine the mechanical properties of SRM materials and less with the instability of SRM slopes and the large deformation phase after instability. However, it must be acknowledged that it is impossible to prevent landslides from occurring in the foreseeable future [23], so it is equally important to investigate the extent of the effects of slope failure as it is to investigate the stability of slopes. As mentioned above, the material point strength reduction method is adopted in this paper to study the stability and post-damage behaviors of SRM slopes. On the one hand, because of the significant advantages of the MPM in solving large deformation problems, e.g., simple imposition of boundary conditions, and higher solution efficiency compared to DEM, SPH, and so on [24]; on the other hand, the combination of the strength reduction method makes the MPM, a method for solving dynamic problems, equally capable of determining the safety factor of a slope. The MPM, first proposed by [PERSON] et al. [25] uses a hybrid Eulerian-Lagrangian description, thus combining the advantages of both the Lagrangian and Eulerian descriptions. All material information is stored in the material point, the grid exists only as a tool for solving the equations, and deformed meshes are discarded, which ensures the reliability of the material point method for modeling large deformation problems. Over the past 20 years, the material point method has evolved considerably, extending a number of stable solution formats [26; 27; 28; 29], and has been applied to a wide range of fields such as geotechnical engineering [30; 31; 32; 33], biomechanics [6], aerospace [34; 35; 36] and so on. This paper uses the MPM to simulate and analyze the SRM slopes. First of all, a material point model of the slope is established. One is a pure soil slope model without considering stones, and the other is an SRM slope model. Next, the mechanical parameters of the slope are reduced, the safety factor of the slope can be determined, and the stones' contribution to the slope's stability is explored. Finally, the whole process of the landslide is studied, and the different damage behaviors of the pure soil slope and SRM slope are compared.