The water level drawdown of reservoir or river often causes the decrease of stability of bank slopes. Establishing a rapid assessment approach for evaluating the stability of slope under the variation of water levels has an important practical significance. Based on the water level drawdown of reservoir or river

and the transient unsteady seepage in clay slope

the program based on shear strength reduction finite element method (SSR-FEM) is developed to compute the factor of safety (FOS) for the slopes under the action of surface water and ground water together. Considering the influences of soil properties

relative permeability ratio and boundary conditions on slopes stability

the relative stability graphic method is presented under the integration parameters of soil properties

relative permeability ratio

drawdown ratio

slope angle

etc. The suggested method can rapidly obtain the FOS of existing slope and the design inclination ratio of planning embankment

and it can also be a helpful supplement for the existing stability charts of simple slope.