Study on the Influence of Rock Block Spatial Distribution on Deformation and Instability of Soil-Rock Mixture Slopes

The collapse of rain-induced soil-rock mixture slopes often exhibits characteristics of suddenness and high destructiveness, and the non-uniform distribution of internal rock blocks can lead to varying collapse forms in these slopes. In this study, typical field soil-rock mixture slopes were proportionally replicated, simulating the deformation and instability processes of slopes with different rock block spatial distributions after rainfall infiltration. The research results indicate that when rock blocks are distributed in the front-middle section, the slope instability mode is characterized by tension cracking and creep-type landslides. When rock blocks are distributed in the rear section, the slope instability mode involves erosion and gully formation. When rock blocks are distributed in the upper layer, the slope instability mode is characterized by toe collapse and surface erosion, and when they are distributed in the middle-lower layer, the slope instability mode involves channel collapse and surface erosion. Additionally, an analysis of the accumulation forms and surface deposition patterns of different types of landslides reveals a positive correlation between the travel distance, width, and area of landslides and rainfall duration. The final ranking of accumulation profiles from largest to smallest is as follows: upper layer > rear section > middle-lower layer > front-middle section. Finally, by studying the development patterns of plastic shear bands in soil-rock mixture slopes under various rock block spatial distributions, the underlying mechanisms of different instability modes are revealed. For tension cracking and creep-type landslides, the development pattern primarily involves "detouring" and "encapsulation" of rock blocks. Erosion and gully formation-type landslides exhibit a development pattern of "detouring" rock blocks. In toe collapse and surface erosion-type landslides, when the plastic shear band develops into the middle-upper layer, the primary development pattern is "detouring" of rock blocks. For channel collapse and surface erosion-type landslides, the development pattern includes "diversion" and "encapsulation" of rock blocks.