Controlling influence of the “perched water structure” on rainfall-induced landslide: A case study of the Yaogou landslide in Zhushan County, Hubei Province

The Yaogou landslide, located in Zhushan County, Hubei Province, exhibits distinctive aquifer characteristics and varying permeability, leading to the retention of groundwater within the landslide after rainfall, forming confined water. This kind of landslide aquifer underlying weakly permeable rock and soil mass is called a “stagnant water structure”. By monitoring a two-year dataset of rainfall, groundwater level, water content and displacement of the Yaogou landslide, it was found that the confined water head of the landslide fell slowly with the sharp rise of rainfall, which showed an obvious "stagnant water" pattern. Geostudio software was used to simulate the rainfall infiltration process, and it was verified that the sliding body was subjected to the action of confined water, and the lifting amplitude and acting position of confined water were basically consistent with the observed situation. The landslide stability coefficient and pressure head exhibited a reverse curve with a consistent curvature. It showed that the "water stagnation structure" of the landslide had a significant controlling effect on the formation of confined water head and the stability of landslide. This emphasizes the significant control exerted by the "water stagnation structure" on confined water head formation and landslide stability.