Analysis of the Influence of Water Level Change on the Seepage Field and Stability of a Slope Based on a Numerical Simulation Method

River floods, dammed lake flood discharge, reservoir seawater recession, etc. all cause the water level in front of a slope to drop, which changes original steady-state seepage field soil, leading harmful instability. To study this phenomenon, numerical model was established through theoretical analysis combined with coupling Seep/W and Slope/W modules GeoStudio finite element software, verified by test results indoor medium sand silt. This paper focuses on effects when drops at different speeds, drop ratios, initial levels, filling materials, matrix suction stability. The conclusions are as follows: (1) greater speed falls, downward force formed body; (2) change curve safety factor higher is steeper falls value constant smaller; (3) decreases an increase ratio; ratio same, loss stability worse if lower; (4) there drawdown levels slope, non-cohesive more prone instability failure than cohesive silt slope; (5) modeling method applied suction, effect increases slope.