Abstract
Located in reservoir area of Dahuaqiao Hydropower Station in Lancang River, the Dahua ancient deposit landslide exhibits high possibility of reactivation due to reservoir impoundment. In this study, physical model tests are conducted to investigate the variations of groundwater, deformation, and failure process of the landslide under different fluctuation speeds of reservoir water level. Influence of groundwater on landslide stability when reservoir water level fluctuating is analyzed then. Results indicate that the seepage pressure caused by water level difference can increase landslide displacement. During the dropping process of reservoir water level, the relationship between landslide displacement and water level difference can be described by a power function model. Groundwater has negative effects on stability of landslides, and the damage is characterized by traction landslide. More attentions should be paid on the displacement of the front edge of the landslide during the first rise and drop of reservoir water level. The study provides indispensable information for scheduling reservoir water level in the Dahuaqiao and others similar reservoir areas, thus having vital importance.
Highlights
In reservoir areas, fluctuation of groundwater level caused by change of reservoir water level is one of major factors inducing and reactivating landslides
The landslide occurred on the left bank of the Vajont Reservoir area in Italy during the impoundment period in 1963[1,2,3]; the Qianjiangping landslide in the Three Gorges Reservoir in China occurred during the first impoundment in 2003[4,5]; both the Teton dam failure in the United States in 1976[6] and the Malpasset arch dam collapse in France in 1954[7] were related to the rapid rise of reservoir water
The groundwater level is applied at the interface between the groundwater level line and bedrock at the trailing edge of the landslide model, and the height of the groundwater level is calculated according to the geometric similarity ratio
Summary
Fluctuation of groundwater level caused by change of reservoir water level is one of major factors inducing and reactivating landslides. Fluctuations of reservoir water level will inevitably lead to fluctuations of groundwater level inside a landslide, which is believed to be the main factor inducing landslides [13,14,15,16,17]. Jia et al [22], Luo et al.[23], He et al.[24], and Wang et al.[25] studied the influence of reservoir water level on landslide stability through physical model tests. An in-depth analysis of the deformation mechanism of Dahua landslide with different reservoir water level fluctuation rates is of great significance for the safe operation of Dahuaqiao Hydropower Station. A large-scale physical model is established using a typical profile of the Dahua landslide, and deformation mechanism of the landslide is analyzed by model test
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