Qianjiangping Landslide near Three Gorges Reservoir: Coupled analysis of Seepage and Slope stability

Abstract

The Qianjiangping landslide occurred on July 14, 2003, near the Three Gorges Reservoir in China. The accident was a large planar rockslide. In order to deeply understand the mechanism and failure process of the landslide, Geo-Studio software was used to simulate and analyze the accident site. The results show that the landslide was caused by the rise of the water level and continuous rainfall. By adding several monitoring points, it was found that the change of pore water pressure in different positions of the slope will be different. The change of water level has a more obvious effect on the pore water pressure at the bottom of the slope while rainfall has a greater impact on the change of pore water on the slope surface. In addition, the results show the impact of rainfall on slope stability is not immediate, because it takes some time for infiltration water to transfer to the bottom of the slope. For soil slope, the influence of different rainfall patterns on slope stability was different. Therefore, the effects of four rainfall patterns (delayed, uniform, normal and advanced) and different rainfall intensities on slope stability are analyzed. The results show that under the influence of an "advanced" rainfall pattern, the cumulative rainfall rate was the fastest. Therefore, the factor of safety of slope decreases the fastest. The cumulative rainfall rate of "normal" and "uniform" patterns was slightly slower than that of advanced patterns, so the time of slope landslide was also slightly later. The accumulated rainfall of the “delayed” pattern was the slowest among the four, and the occurrence time of landslide was also the latest. Finally, by increasing the rainfall intensity, it is found that the rainfall intensity has an important impact on the slope stability, and the total rainfall is proportional to the pore water pressure.