Reactivation Characteristics and Failure Mechanism of the Hongyan landslide

This paper studies the Hongyan landslides with complex reactivation mechanisms induced by human engineering activities.Through field investigation, drilling, in site monitoring and numerical simulation, the reactivation characteristics and instability mechanism of the Hongyan landslide were systematically studied.The results show that the regional lithology, topographic characteristics, geological structure and engineering activities have a certain promoting effect on the reactivation of the Hongyan landslide; the existence of clay in the sliding body and the layered structure in the sliding body enhances the sensitivity of the slope.The free surface of the slope creates favorable conditions for the subsequent deformation of the sliding body; the sliding body is mainly the ancient landslide accumulation body, and the layered structure before the slope sliding is retained in the ancient landslide accumulation body; the excavation of the slope reduces the anti-sliding force and changes the free surface conditions, which directly leads to the reactivation of the landslide; during the deformation process, due to the change of the free surface conditions, the sliding body shows the characteristics of counterclockwise deflection.The reactivation of the Hongyan landslide is the result of the interaction of multiple inducing factors, and its instability mechanism is complex.This study is of great significance for the hazard evaluation of such ancient landslides.