Deformation mechanism of the Taping H1 landslide in Wushan County in the Three Gorges Reservoir area

Affected by the water level fluctuations and heavy rainfall, several bedding rock landslides have reactivated since the 175 m trail impoundment in the Three Gorges Reservoir area. The Taping H1 landslide near Quchi in Wushan County is taken as an example, and combining the landslide investigation and monitoring, the deformation characteristics and reactivation mechanism of the landslide are analyzed. The research results show that (1) the Taping H1 landslide is an ancient bedding rock landslide, the rock mass is fragmented and is mainly composed of soft and hard sandstone, mudstone and shale of the Triassic Xiangxi Group, which is sandwiched by multiple layers of weak inter layers, forming a multi-stage slip zone to control landslide deformation. (2) According to the monitoring of surface and underground displacements, the deformation of the landslide is divided into three regions. The maximum horizontal displacement of the landslide leading zone of the landslide with the largest displacement has reached 80 cm. The middle area of the landslide is slowly deformed, and the area of the rear Quchi Township is relatively stable. (3) The numerical simulation results show that the water level fluctuations influences the deformation and stability of the landslide leading edge which is below the water surface, and the heavy rainfall infiltration along the structural plane accelerates the deformation of the front area of the landslide. The middle and front areas of the Taping H1 landslide is currently in the stage of continuous deformation. Under the combined influence of water level fluctuations and short-term heavy rainfall, the Taping H1 landslide shows a slow deformation during the annual flood season, which is consistent with the monitoring results. Landslide prevention projects are urgently needed to improve the stability of the landslide and ensure the safety of the town.