Effect of Nonlinear Soil Model on Seismic Response of Slopes Composed of Granular Soil

Yonghee Lee,Duhee Park,Hak-Sung Kim,Muhammad Irslan Khalid,Yonggook Lee,Bingxiang Yuan

doi:10.1155/2020/8890247

Abstract

A series of two-dimensional finite element analyses are performed to simulate the seismic response of slope composed of granular soil. Four sets of input parameters for the nonlinear soil model are used to fit the reference the shear modulus reduction and damping curves, thereby to evaluate the influence of the nonlinear soil model. The first set is fitted to the shear modulus reduction curve. The second and third sets are fitted simultaneously to both shear modulus reduction and damping curves. The final set applied the shear strength adjustment to adequately capture the nonlinear soil response at large strains. The accuracy of each set of parameters are evaluated through comparison with centrifuge model test measurements. It is observed that the nonlinear soil model has a marginal influence on the acceleration response. On the contrary, the vertical settlement is highly influenced by the nonlinear soil model. The discrepancy is shown to increase with an increase in the intensity of the input ground motion. It is demonstrated that the adjustment for the shear strength is important in performing seismic analyses of slopes, which is most often ignored in practice. Based on the results, practical guidelines on how to select the parameters for the nonlinear soil model are provided.

Highlights

Makdisi and Seed [10] performed dynamic finite element analyses using the equivalent linear soil model to develop a simplified procedure to estimate the permanent
The earthquake ground motion induces cyclic motion, producing nonlinear hysteretic stress-strain curve. e nonlinear soil response is reported to initiate at very small strains, and capturing this is important in a dynamic simulation. e nonlinear soil behavior is typically represented by the normalized shear modulus reduction and damping ratio curve. e shear modulus reduction curve represents the decrease of the secant shear modulus with an increase in strain. e damping ratio curve plots the increase in the area of the hysteretic curve with an increase in shear strain. e performance of a nonlinear constitutive model is calibrated by comparing the shear modulus reduction and damping curves derived from the nonlinear model with the target curves
E nonlinear model was fitted to the shear modulus reduction and damping curves of Darendeli [39], outlined below using three procedures. e first procedure matches the shear modulus reduction curve, denoted as the modulus reduction fit (MR) model. e second procedure fits both modulus reduction and damping curves; it is termed the modulus reduction and damping fit (MRD) model. e third procedure fits the shear modulus reduction curve in addition to adjusting the curve to match the target shear strength

Summary

Introduction

Makdisi and Seed [10] performed dynamic finite element analyses using the equivalent linear soil model to develop a simplified procedure to estimate the permanent. E parameters for the model were selected to fit the shear modulus reduction and damping curves of Darendeli [39] at the mid depth of each soil layer, the details of which are presented .

Results

Conclusion