Three-Dimensional Seismic Response of a Large Embedded Structure and Induced Earth Pressure

Abstract

For large embedded structures, soil-structure interaction (SSI) plays a major role in dictating the overall seismic response. In light of recent strong seismic excitation affecting such structures, three-dimensional (3D) response as well as nonlinear (NL) soil behavior are among the areas of increased interest. As such, this paper presents a series of 3D NL numerical studies conducted to shed more light on the involved SSI mechanisms. In this parametric study, consideration is given to factors such as the effect of soil own-weight stress state, the structure-ground interface properties, and the intensity of seismic excitation. For comparison, additional time-domain simulations explore the use of linear soil (LS) properties derived from an equivalent linear (EL) site-response analysis. For the purposes of this study, the structure is taken to be cylindrical and fully embedded in the ground. Depending on the level of attained nonlinear response, the influence of the following modeling considerations is discussed: (1) employing the NL versus LS formulation, (2) initial own-weight lateral earth pressure stress state, and (3) the soil-structure interface characteristics. Accelerations along the profile of the structure as well as earth pressure on the walls and floor are among the main parameters of interest. In the free field it was observed that the LS representation adequately matches the NL acceleration response up to frequencies of about 10 Hz. Furthermore, both formulations generally resulted in remarkably close estimates of the structural response. Nevertheless, exceptions include the following: (1) the wall lateral earth pressure and floor pressure were noticeably different, and (2) the potential change in the soil initial stress state due to seismic excitation was manifested only in the NL modeling scenarios.