Deformation mechanism and stability evaluation of Tanjiawan landslide based on multi-source data

Abstract

In view of the Tanjiawan landslide, which occurred in the northwest of Zigui County in May 2016, this paper preliminarily defined the affected area, characteristics and occurrence time sequence of the landslide based on multi-source data such as satellite remote sensing images, field survey data and historical data.By means of drilling, trough exploration and geophysical exploration, indoor and outdoor experiments were carried out to clarify the stratum characteristics and the physical and mechanical properties of the rock and soil mass in the landslide area.By analyzing the crack displacement and GPS data in the area, the deformation mechanism of the slope was discussed and the stability of the area was evaluated.The results show that: ①The Tanjiawan landslide belongs to reservoir descending landslide with irregular "chair-shaped" medium-sized loose layer; the surface morphology, geological structure and lithology of landslide area determine the formation and development of landslide, and the joint action of reservoir water level and precipitation stimulates the development of landslide; ②The landslide is divided into three levels of sliding body according to the time sequence, showing multiple, multi-layered and mutual shadows on the whole.The third-order sliding body has the characteristics of traction; ③The groundwater level in the landslide body decreases with the decrease of the reservoir level, but the rate of decline is slower than the reservoir level, and the hydraulic gradient and permeability in the slope body become significantly larger.Heavy rainfall at this time will lead to the occurrence of groundwater in the slope body, softening of rock and soil mass, and exacerbating landslide deformation, and necessary protective measures must be applied; ④Stability analysis shows that the landslide is in a critical stable state.Once rainfall and reservoir water level change, instability sliding may occur in some sections.

Keywords

• multi-source data
• reservoir descending landslide
• deformation characteristics
• instability mechanism