Impact of Variation of Small Strain Shear Modulus on Seismic Slope Stability Analysis of a Levee: A Sensitivity Analysis

In this research, a sensitivity analysis was performed to study the effect of variation in maximum shear modulus (G(max)) values of different layers of a levee structure on the seismic response and stability of the levee slopes. The analysis was implemented by systematically varying the Gmax values of the different layers to simulate the effect of possible variation in estimated Gmax values obtained from in-situ/laboratory tests and correlation equations. The Gmax values of the layers were altered in two ways: variation in (1) individual layers; and (2) group of layers; thus, simulating the effect of incorrect estimation in Gmax values of a particular layer and a group of layers, respectively. The levee was subjected to the acceleration time-history data of two earthquakes with considerably different predominant frequencies. It was observed that the inaccurate estimation of Gmax values, especially for the deeper layers, significantly affects the natural frequency and peak crest acceleration. Moreover, a prominent change in the factor of safety of slopes under seismic loading conditions was observed with variation of Gmax values for the near resonance condition. The effects were pronounced when the Gmax values were varied for a group of layers, rather than individual layers.