Slope stability analysis method considering transfer of sliding failure surface and influence of engineered berm

The engineered berm is a general measure to increase the slope stability for valley landfills and the horizontal expansion of existing landfills. The transfer of sliding failure surface between different interfaces in composite liner system has been proved. The slope stability analysis method considering transfer of sliding failure surface and influence of engineered berm is not available. A five-wedge slope stability analysis method is established under the limit equilibrium condition using the failure surface transfer point in liner system as the demarcation and dividing the sliding waste body into five wedges. The research results show that the proposed method can be used to calculate the slope stability of waste filling considering the transfer of sliding failure surface and influence of engineered berm. The safety factor from the new analysis method is less than that without considering the transfer of sliding failure surface. More dangerous state can be found by the new method. The safety factor of slope stability increases with the increasing height of engineered berm. There is an optimum gradient. When the back slope of engineered berm is less than this value, the failure of back slope of the berm occurs. Otherwise the failure under the bottom of the berm happens. The most dangerous failure surface is along the back slope and subgrade slope in the landfill and liner on the back slope of engineered berm or the bottom of the berm.