## 1 Introduction  
The main methods of slope stability analysis are the limit equilibrium method, the finite element strength reduction method, as well as the reliability method, the fuzzy mathematical method, and the artificial intelligence method [1]. The limit equilibrium method takes into account the strength properties of the soil but does not take into account the soil's constitutive model and cannot reflect the relationship between stress and strain within the slope. The finite element method (FEM) of strength reduction overcomes the difficulties encountered in the former method and has a high degree of acceptance in the field of slope stability analysis because it can take into account the non-linear constitutive relationships of geotechnical materials and deal with complex working conditions such as excavation and shoring [2; 3; 4; 5]. However, the solution format of the FEM makes it difficult or impossible to solve the subsequent behaviors of the slope after instability [6]. Methods such as reliability methods, fuzzy mathematical methods, and artificial intelligence methods are less interpretable, the conclusions obtained by utilizing these methods are often not of sufficient physical significance, and they rely on the experience of the engineer to work well [7]. In the specific implementation of the strength reduction method, the judgment criteria are the key, but at present, there is a big controversy on the selection of the judging criteria. For example, [PERSON] et al. [8] used the displacement in the vertical direction at the top point of the slope and the lateral displacement at the foot point of the slope, whether there is a sudden variation, as the criterion for slope instability. [PERSON] et al. and [PERSON] et al. [9; 10]considered that the non-convergence of FEM should be used as the criterion for slope failure. [PERSON] et al. [11] and [PERSON] et al. [12] considered that the plastic zone or the generalized plastic shear strain running from the foot to the top of the slope should be used as a sign of slope failure. In addition, there are significant differences in the magnitude of the stability coefficients obtained with different determinants. It is worthwhile to investigate whether a simple numerical calculation method can be used to improve the judgment criteria of the strength reduction method and if MPM is a more suitable algorithm. [PERSON] et al. [13] have carried out more work in this area. They have proposed the material point strength reduction method and carried out a stability analysis of a slope and compared it with the finite element strength reduction method to illustrate the advantages of the material point strength reduction method. In this paper, the stability of SRM slopes is studied by the material point strength reduction method, using the occurrence of sudden changes in vertical displacement of the slope as a criterion for instability. The damage behaviors of the slope after instability are also analyzed, including displacement, kinetic energy changes et al. Previous numerical simulations on SRM slopes can be divided into two main areas: one is based on stability analysis represented by the FEM. [PERSON] et al. [14] established the SRM slope model using digital image processing technology. On this basis, the stability study was carried out using the finite element strength reduction method. They found that the distribution of shear bands presents prominent rock-surrounding characteristics, and the stability coefficient of the SRM slope is higher than that of an equivalent homogeneous soil slope. [PERSON] et al. [3] proposed an SRM slope model which can consider stones of arbitrary shape and realize different block size distribution and stones content. Then, the FEM was used to simulate the stability of the SRM slope with different block sizes and stones content.