A Modified Newmark Analysis of Lateral Spreading Based on Liquefaction Initiation Time

Abstract

The displacement of lateral spreading induced by liquefaction is of great interest to engineering practice. In this paper, a modified Newmark sliding block method was proposed to predict the displacement magnitude of lateral spreading. Two input factors, i.e., yield acceleration and seismic motion, used in the Newmark sliding block method were modified to incorporate the mechanism of lateral spreading. The modified Newmark sliding block method used the input motion after liquefaction time and the yield acceleration corresponded to the residual shear strength of liquefiable soil. First, a residual shear strength model for liquefied soil was developed based on history cases of lateral spreading to calculate the yield acceleration using the limit equilibrium method. Then, a liquefaction initiation time identification method was proposed to consider the influence of liquefaction on input motion and obtain the seismic motion post liquefaction. The lateral spreading of the Wildlife site case was used to illustrate the modified Newmark sliding block method, as well as a set of lateral spreading cases was used to validate the applicability of the proposed method. The method proposed in this paper indicates that considering the liquefaction initiation time can provide a reasonable prediction of lateral spreading.