The stability of landslide is affected by the drawdown of reservoir water level. A polynomial constrained optimized model for soil-water characteristic curve and a new restrict function for overflow surface are put forward. Based on these

a saturated-unsaturated seepage program is edited with APDL in ANSYS. Zhaoshuling Landslide is taken as an example

firstly the physical model is established through Nuclear Magnetic Resonance and bore data，and then the seepage fields are simulated when the Yangtze River water level falls from 175 m to 145 m at different speeds

the stability of the landslide at different times is also analyzed. The result shows that the bigger the fall speed is

the least the minimum value of the stability coefficient is

and the earlier the value comes.