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

ABSTRACT Rainfall‐induced failures of soil–rock mixture slopes are characterized by abruptness and high destructiveness. Heterogeneous spatial distribution of rock blocks significantly differentiates slope instability modes. In this study, proportional physical model tests were performed on typical field soil–rock mixture slopes to simulate deformation and instability evolution under rainfall infiltration with various rock block spatial configurations. The results reveal distinct instability patterns: slopes with front‐middle rock blocks undergo tensile cracking and creep sliding failure (tensile‐creep slide); rear‐distributed rock blocks induce hydraulic erosion and gully incision (gully erosion‐flow); upper‐layer rock masses result in toe collapse and superficial erosion (toe collapse‐surface erosion); middle‐lower rock arrangements trigger channel collapse combined with surface denudation (channel collapse‐surface erosion). Landslide sliding distance, diffusion width and deposition area are positively correlated with rainfall duration. The deposition scale follows a descending order: upper layer > rear section > middle‐lower layer > front‐middle section. Evolution laws of plastic shear bands reveal intrinsic failure mechanisms. Shear bands bypass and wrap around rock blocks in tensile‐creep landslides and merely bypass rock blocks in gully erosion failures. For toe collapse slopes, shear bands bypass rock fragments when propagating to mid‐upper strata. Channel collapse slopes present shear diversion and rock block encapsulation.