Seismic Translational Failure Analysis of MSW Landfills Using Modified Pseudo-Dynamic Approach

Abstract

For landfills situated in regions of high seismicity, seismic inertial forces may be a triggering factor for the translational stability of municipal solid waste (MSW) landfills. This paper applies a modified pseudodynamic method to the seismic translational stability analysis of landfills. In the present study, a closed-form solution is proposed to obtain the factor of safety and the yield acceleration coefficient for a typical side-hill-type landfill resting on a rigid base using limit equilibrium method. The acceleration ratio obtained in the present study compares well with that obtained using popular ground response analysis software for a given set of input parameters. The acceleration ratio is the ratio of seismic acceleration at the top of the landfill to the seismic acceleration at the base of the landfill. From parametric study, it is observed that the landfill is vulnerable to seismic damage in low-frequency input motions. At low frequencies, the seismic inertia force is in phase at all depths. The seismic force acting on the landfill mass is reduced at higher frequencies, where landfill mass is entering into higher modes of vibration, where some portion of landfill is moving in one direction and the remaining portion is moving in opposite direction. The results obtained are compared with the available literature sharing the same input parameters. The values of the factor of safety obtained in the present study are higher than those calculated using pseudostatic and pseudodynamic approaches. For the input parameters assigned in the comparison, the landfill mass in the third mode of vibration is the reason for the greater values of the factor of safety. Material damping may be also a reason for the higher factor of safety values.