Layered gravel soil slope stability of a waste dump considering long-term hard rain

In order to examine the effect of long-term hard rain on the layered gravel soil slope stability of a waste dump, the for-mula derivation relating natural water content, natural unit weight and natural volumetric water content was conducted to help to con-firm the initial suction of the slope rapidly. A numerical analysis model of a waste dump with a layered gravel soil slope based on the finite element method was established to analyze the saturated-unsaturated seepage, coupled stress-pore pressure and slope stability. The results show that a seepage channel will be formed in the slope surface due to its high permeability during the rain. If there exists a water-resisting soil layer in the bottom of the slope, water will come out from the slope toe. The displacement of the slope increases with a decreasing rate during the rain and decreases immediately after the rain. The stability coefficient of the slope decreases rapidly at the beginning of the rain. Then the stability coefficient barely changes till the rain stops as the seepage in the slope surface becomes stable. After the rain, the stability coefficient increases slowly. It is most possible for the layered gravel soil slope of a waste dump to fail in the middle and late stages of long-term hard rain.