Abstract: Based on the principles of the unsaturated soil mechanics and circular the slicing method, this paper analyzes the mechanism of the stability reduction under the action of seepage. The weak zones in the slope are simulated with contact elements. The analytical model of soil slopes with weak zones and coupled with stress and seepage is established by using MIDAS GTS software. In the slope stability model, the strength reduction and limit equilibrium methods are considered in the seepage analysis. The results indicate that, the slope instability criterion cannot be purely based on the connection of plastic zones. The results from the numerical analysis with strength reduction method are very similar to those with limit equilibrium approach. The weak planes and seepage have significant impacts on the deformation and stress redistribution as well as stability of slopes.

Key words: slope mitigation, structural surfaces, coupled analysis, slope stability