DEFORMATION CHARACTERISTICS AND INSTABILITY MECHANISM OF LARGE MONOCLINAL LAYERED NEOGENIC BEDROCK LANDSLIDE IN THREE GORGES RESERVOIR AREA

This paper take the Jiaodingfeng Ⅱ landslide in Wushan County of the Three Gorges Reservoir area as an example and combines the reservoir water level changes and geological environment conditions data. It analyzes the deformation characteristics,formation mechanism and development trend of the landslide in detail. It uses field survey and mapping,UAV,engineering geological drilling,surface and deep displacement monitoring and other techniques. The volume of the landslide is about 250×10⁴ m³. It is a large monoclinal neogenic bedrock landslide. The height difference between the front and rear edges of the landslide is about 380 m. The leading-edge shear outlet is high and steep and is located below the reservoir water level. The deep monitoring data show that there are two sliding zone in the water-level-fluctuation zone. The two zones are located between 12.0~17.0 m and 25.0~30.0 m from the slope. At present,the landslide is in the creep deformation stage. Under the influence of landform,stratigraphic structure,deterioration of the water-fluctuation zone and water,the vertical displacement continues to increase. The front deterioration zone has a high possibility of sliding failure and instability,and there is a risk of landslide surge disaster chain. It is suggested to carry out continuous observation and research on the deterioration system of the fluctuation zone in the reservoir area to improve the ability of identification and early warning of new landslide disasters in the reservoir area.