An improved transfer coefficient method considering the combined effect of reservoir level variation and rainfall and its application in the stability evaluation of multistage sliding ancient landslides

In this paper, by considering the dynamic water pressure and particle migration effect caused by reservoir level variation, the weakening effect of slip zone soil influenced by rainfall infiltration, and the interaction force between multistage sliding bodies, an improved transfer coefficient method for multistage sliding ancient landslide is proposed under the combined action of reservoir level variation and rainfall. The results show that (1) the combined action of reservoir level variation and rainfall has a significant influence on the stability of multistage sliding ancient landslides. (2) The sliding force calculated by the improved transfer coefficient method is smaller than the calculation result by the traditional transfer coefficient method, and the residual sliding force is larger. The different sliding body stability coefficient is reduced by about 28.84, 18.13, 19.26, and 21.01%, respectively. (3) The stability results calculated by the traditional transfer coefficient are higher than the improved transfer coefficient method, which may lead to deviation in the multistage sliding ancient landslide stable state judgment. (4) This improved transfer coefficient method can provide a reference for the multistage sliding ancient landslides stability accurate evaluation in hydropower station reservoir area.