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

Abstract

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