Landslide Reliability Analysis Based on Transfer Coefficient Method: A Case Study from Three Gorges Reservoir

To evaluate the reliability of a landslide in a reservoir, the universal transfer coefficient method, which is popularized by the Chinese standard, is adopted as performance function in this study for: (1) common deterministic method stability evaluation; (2) reliability evaluation based on a Monte Carlo method; (3) comparison of landslide reliability under different water levels and under different correlation coefficients between soil shear strength parameters (c, Φ), respectively with mean, standard deviation, reliability coefficient and failure probability. This article uses the Bazimen (八字门) landslide, which is located at the outlet of Xiangxi (香溪) River in the Three Gorges Reservoir, as an example to evaluate its stability and reliability under different water levels with two-dimensional deterministic and probabilistic methods. With the assumption that constant mean and normal distributed shear strength parameters (c, Φ), correlation coefficient ρ_{c, Φ}=−1 based reliability analysis, compared with ρ_{c, Φ}=0 and 1, indicates obviously more increase of reliability index and lower standard deviation as water levels rise. To the case of a certain water level, ρ_{c, Φ}=−1 does not have constantly positive or negative effects on landslide reliability compared with ρ_{c, Φ}=0 or 1, but is associated with water level. Whereas the safety factor F_s by deterministic method, which is almost the same value as corresponding mean of safety factor from probabilistic analysis, will increase slightly as water level increases.