SS-NEWMARK MODEL FOR EARTHQUKE-INDUCED SLOPE FAILURE

Abstract

 In a conventional Newmark slope sliding model, a soil block is assumed to slide along a rigid sliding plane in a rigid-perfect plastic manner when input acceleration exceeds a yield value. In reality, a small deformation may well be expected to occur immediately before the sliding starts due to shear deformation in a weak sliding layer underneath the sliding block as indicated from previous model shake table tests. In this research, Spring Supported-Newmark model (SS-Newmark model) is developed combining in sequence a spring for pre-sliding deformation and a slider identical to the Newmark model, and the responses of the model to sinusoidal and earthquake acceleration motions have been calculated and compared with those by the conventional Newmark model. It is found that the SS-Newmark model can evaluate the yield accelerations clearly exceeding those in the conventional Newmark model, and such an exceedance has actually been observed in slope failures in model shaking table tests. According to example calculations on typical slopes of realistic design parameters shaken by earthquake records which triggered a plenty of slope failures, the number of successive sliding and associated sliding distance of failed debris are calculated evidently smaller in this model than in the conventional model by considering small pre-sliding yield displacements. Thus, the newly developed SS-Newmark model can be more realistic in evaluating seismic slope behavior by employing a small pre-sliding slope deformation as a slide-specific design parameter.