Study on the deformation mechanism of anti-piles in Majiagou landslide in Three Gorges Reservoir Area, China

Abstract

In the Majiagou landslide of the Three Gorges Reservoir Area, there appears a wide crack between the anti-pile and sliding body behind the piles, which can hardly be clarified by the sliding force of the sliding body. Therefore, the deformation mechanism of anti-piles in the Majiagou landslide was studied to explain how the crack appears between the anti-pile and sliding body behind the piles from perspectives of embedded rock degradation and declining water level. The mechanical degradation of the embedded rock was studied experimentally with triaxial compression and Brazilian splitting tests at first. Then, the embedded rock degradation and declining water level were introduced into the FLAC3D model, where the deformation mechanism of anti-piles and soils behind the anti-piles were studied. The results show that the rock resistances in front of anti-piles gradually decrease and the embedding effect of anti-piles gradually weakens due to the embedded rock degradation, resulting in plastic deformation in the rock and forward inclination of anti-piles. In addition, the declining water level leads to an increasing seepage force, leading to an increasing sliding deformation of the sliding body in front of the anti-piles, which weakens the front support of the anti-pile. Thus, the anti-pile displacements continually increase and exceed those of the sliding body behind the pile, and a wide crack appears between the anti-pile and sliding body behind the piles as a result. Consequently, the mechanical and deformation parameters after degradation should be employed for the reinforcement design of anti-piles in reservoir bank slopes.