A study of deformation mechanism and stability evaluation of the Chenxiyu landslide in western Hunan

Shallow landslide hazards widely occur in China. The distribution regularity of this type of landslide areas is poor, and it is characterized by suddenness, concealment and destructiveness. In the Wuling Mountains, geological conditions are complex, rainfall is abundant, human engineering activities are intense, and sudden geological disasters occur frequently, especially the shallow landslides induced by rainfall. The Chenxiyu landslide in Cili county of western Hunan is taken as an example, and monitoring of rainfall, matric suction, groundwater levels and surface deformation is carried out. Combined with field investigation and monitoring results of the landslide, the formation conditions and deformation mechanism of the landslide are carried out. By considering the contribution of matrix suction to slope stability, the strength reduction finite element method is extended to the unsaturated soil slope, and the stability of landslide stability under different rainfall conditions is calculated. The results show that when heavy rainfall falls on the landslide, the matrix suction value in the slope decreases rapidly and does not change after a certain value (about 9.5 kPa). The groundwater level in the slope is significantly affected by seasonal rainfall and the groundwater is caused by short-term heavy rainfall. The geomechanics of the Chenxiyu landslide is due to the creeping-type soil landslide, and the movement form is a shallow landslide along the base-covered interface. Short-term heavy rainfall is the most critical factor inducing the landslide deformation. The rainfall warning value of the Chenxiyu landslide under continuous rainfall is about 280 mm, and the warning value of rainfall intensity under short-term heavy rainfall is about 240 mm/d.