Abstract
The existing research data show that, after reservoir impoundment, due to the repeated rise and fall of water level and water-rock interaction, the mechanical parameters of landslide are reduced, which will have an adverse effect on the stability of landslide. Therefore, sufficient attention must be paid to the stability of slope after reservoir impoundment. Hejia landslide is the largest landslide near the bank of Miaojiaba hydropower station, and its stability plays an important role in the normal operation of the hydropower station. Through field investigation and analysis of regional geological conditions, it is concluded that Hejia landslide is a large-scale landslide, through long-term sliding-bending deformation; it is generated from the external hard rock with thick layers and sliding zone for layered soft rock; the formation mechanism of landslide is as follows: (1) high-steep and hard-soft layered slope is the slope structure condition that caused the large landslide; (2) the existence of thick soft rock belt provides material conditions for the formation of slip surface; (3) certain air conditions provide displacement space for the separation and disintegration of the sliding body, and the landslide is stable at present. Numerical analysis results show that reservoir impoundment will adversely affect the stability of landslide. In order to ensure the normal operation of power station, certain engineering measures must be taken to treat Hejia landslide. After taking measures, years of monitoring data show that the deformation of Hejia landslide tends to be stable, and the current operation is normal, indicating that the engineering treatment measures are reasonable and feasible.
Highlights
Over the past 20 years, most hydropower stations in China have been constructed in the western mountains and valleys with harsh natural conditions, poor geological conditions, and broken rock masses
Unfavorable geologic bodies such as landslide and toppling mass are widely distributed. They will have an adverse effect on the construction and operation of the hydropower stations. ere were landslides in the Longyangxia Hydropower Station [1], Lijiaxia Hydropower Station [2], Manwan Hydropower Station [3], and Laxiwa Hydropower Station [4] after their completion and operation
The adits of the Hejia landslide were first excavated in 1990. e field survey in 2009 suggested that the main adits retained their original shape without any supports [17]. is suggested that the sliding mass composed of slate near the sliding zone had good integrity and tightness
Summary
Over the past 20 years, most hydropower stations in China have been constructed in the western mountains and valleys with harsh natural conditions, poor geological conditions, and broken rock masses. Unfavorable geologic bodies such as landslide and toppling mass are widely distributed If improperly treated, they will have an adverse effect on the construction and operation of the hydropower stations. Xiao et al [13] conducted a model test to study slope deformation under rainfall and the variation of reservoir water level. E influence of the change of the rainfall conditions on the VWC and PWP was considered He et al [15] analyzed the stability of slope under the change of water level. To control flood and generate power, large hydropower stations have to frequently change the water level of the reservoir during the operation, which greatly affects the slope stability. Backed by results from the field survey and analysis of regional geology, it carried out a numerical analysis of the landslide stability to provide basis for engineering design
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