The Influence of Water Level Fluctuation on the Bank Landslide Stability

The water level will periodically fluctuate between 145 and 175m since normal water level storage in Three Gorges reservoir, while the ground water seepage of landslide will be subject to great changes, which may lead to landslide instability. So it is of great significance to study the influence of water level fluctuatation on the bank landslide stability. In this paper, a polynomial constrained optimized model for soil-water characteristic curve is put forward and the saturated-unsaturated seepage flow numerical model is applied. In addition, Zhaoshuling landslide is taken as an example, water seepage fields are simulated by using finite element method with the water level fluctuation between 145 and 175m. The transient pore water pressures are used for limit equilibrium analyses of landslides with taking the effects of suction on shear strength of unsaturated soils into consideration. Then we discuss the effect of the fluctuation of water level in Three Gorges reservoir on the bank landslide stability. The result shows that a polynomial constrained optimized model may well fit the characteristic curve of soil and water of unsaturated soil. The stability coefficient increases gradually in general along with reservoir water level rise and the stability coefficient decreases gradually in general along with the fall of reservoir water level. However, when the reservoir water level reached 155m, whether it rises from 145m or falls from 175m, the stability coefficient is smallest; while the stability coefficient in period of reservoir water level rising from 145m to 175m is larger than that in period of falling from 175m to 145m.