Dynamic Analyses of Nonlinear Behavior and Stability of a Slope during Strong Ground Motions

This study aims to examine dynamic behavior and dynamic stability of a slope during strong earthquake motions. Nonlinear finite element method is employed in this study. The effect of vertical excitation on the dynamic response of the slope was investigated first. It was clarified that the vertical excitation did not affect the horizontal acceleration, velocity, displacement and the vertical displacement. Then, material nonlinearity of soil was introduced to examine the effect of the nonlinearity on the response of the slope. The soil was assumed to be elasto-perfect plastic body here. The nonlinearity decreased response acceleration and increased response displacement. Response velocity was not affected by the nonlinearity. Finally, stability of the slope under the seismic load was examined. Safety factors against sliding obtained from the dynamic stresses in the slope were compared with those from conventional method, i.e., the Bishop's method. The safety factor obtained from the static method was lower than that from the dynamic analysis. This means that the actual slope would be safe even when the value from the static analysis is the value critical from sliding to take place.