Analysis of the formation mechanism of rainfall-induced loess landslide: A case study of Beiyin landslide

Abstract

The increase in extreme precipitation in summer is one of the clearest changes in climate observed in Shanxi Province, China. The loess is dry, loose uncemented, and has well-developed internal pores in initial state. When extreme rainfall occurs, the special structure of loess provides a favorable channel for rainwater infiltration, which means decreasing the shear strength parameters. Loess landslide induced by extreme rainfall has caused great economic losses and casualties. This paper takes the Beiyin landslide as an example, the seepage field of the loess slope under rainfall infiltration is analyzed by the finite element method, and the stability of the loess slope is analyzed by the limit equilibrium method based on field survey. The pore water pressure, saturation zone, and horizontal seepage velocity at different altitudes of the loess landslide are investigated under various extreme precipitation. The results showed that the concentrated infiltration of extreme rainfall was in the trailing edge of the landslide, formed a saturated zone in the Tertiary water-resisting clay layer, and extended to the slope angle. When the saturated zone is formed in the middle shallow layer of the landslide and connects with the saturated zone of the trailing edge, the sliding force of each block is greater than the anti-sliding force in the sliding section and the slope will be unstable.