Seismic stability analysis of downstream slope on the rockfill dams

The Sweden circular method and the Bishop simplified method were used commonly on seismic stability analysis of rockfill dam slope. The shear strength of the soil is originally expressed by MohrCoulomb failure criterion as a linear function. But many tests show the shear strength of the rockfill material is a nonlinear function of the normal stress. Some papers have analyzed the seismic stability of the rockfill dam slope by the nonlinear shear strength of the rockfill material. But the suited safety factor criterion was not clarified. In this paper, stability safety factors of the rockfill dam slope are compared by finite element method and limiting equilibrium method by the use of linear and nonlinear shear strength. The result shows the safety factor of Bishop method is larger 2%～10% than Sweden circular method, and factor of nonlinear shear strength is larger 15%～25% than linear. So the safety factor criterion of nonlinear shear strength should larger than linear.