Study on Mechanical Response and Stability Algorithm of Soft and Hard Rock Interbedded Slope Excavation

Based on the actual engineering geological survey, the mechanical response mechanism and sliding surface characteristics of the interbedded slope containing six layers of soft and hard rock during excavation under heavy rain conditions are studied by numerical simulation, and the composite sliding surface stability algorithm of the layered slope is established by using the penalty function. The research shows that, during the excavation, the distribution characteristics of stress, strain, plastic zone, and horizontal displacement along the bedding plane are obvious; the stress is concentrated in the hard rock layer; however, the strain and plastic zone are concentrated in the soft rock layer. When the ratio of the maximum vertical displacement to the maximum horizontal displacement is less than 1.85, the slope will slide. According to the relative position of the soft rock layer and the toe of the slope, the sliding surface of soft and hard rock interbedded slope can be divided into two types, namely, circular-straight sliding surface and circular-straight-circular sliding surface. The verification shows that the composite sliding surface algorithm objectively reflects the destruction of the slope by bedding sliding and can reasonably evaluate the safety of soft and hard rock interbedded slope.