Failure mechanism of boulder-embedded slope under excavation disturbance and rainfall

Abstract

Due to the uneven weathering of rocks, boulders can exist inside a slope, making the deformation and failure mechanism of the slope very complex. By analyzing the failure characteristics of a boulder-embedded slope under alternating excavation and rainfall, two classical instability modes are proposed, i.e., boulder instability and soil instability. For the soil instability, three failure processes may occur, including the sliding surface above the boulder, the sliding surface below the boulder, and the sliding surface intersecting the boulder. Meanwhile, the interaction between soil and boulder can also vary during different failure phases. Furthermore, the slope sliding deformation, failure mechanism, and soil-boulder interaction are investigated by on-site monitoring and numerical simulation. The results show that the boulders play an anti-sliding role and block the formation of deep sliding surface, resulting in the shallow soil instability and local large deformation of the studied slope. Besides, during the slope sliding deformation, three failure processes of the soils appear one after another, and the soils may slide along the bottom or top of the boulders because of the hindering effect of the boulders.