A Numerical Evaluation of Seismic Response of Shallow Soil Deposits

This paper employs one-dimensional numerical ground response analysis models to investigate seismic response of shallow cohesive and non-cohesive soil deposits on vertical propagation of horizontal shear waves. Soil response is modelled by traditional equivalent-linear (EL) frequency-domain analysis using DEEPSOIL software and nonlinear (NL) time-domain analysis using OPENSEES software. The analysis is performed on soil columns of different heights to account for depth dependency of responses. Input rock outcropping motions are selected from far-field and near-field time histories and scaled to various shaking levels to evaluate soil nonlinearity level. The results show that the shallow soil deposits have capability of amplifying the input motion considerably. Moreover, With increasing soil depth, greater damping and shifting in the dominant periods of the computed spectra occur and maximum value of spectrums increases. These results for shallow soil deposits, highlight the need to consider the full depth of the soil column to perform local ground response analysis.