Structure–soil–structure interaction (SSSI) of adjacent buildings with shallow foundations on liquefiable soil

Abstract

AbstractThis paper studies the effect of structure–soil–structure interaction (SSSI) on the seismic response of neighboring structures with shallow foundations on liquefiable sand. The problem is studied through coupled hydromechanical analyses. Nonlinear soil response is modeled with PM4Sand, calibrated on the basis of soil element tests of Hostun sand. The numerical methodology has been compared against six centrifuge model tests, showcasing its ability to predict the settlements. Three idealized structures of width B are considered, of different aspect ratio and foundation bearing pressure q, founded on two liquefiable layer depths, DL/B = 1 and 2. Initially, the response of a single building is studied, offering insights on the developing failure mechanisms. While the settlement increases with q in the case of a deep (DL/B = 2) layer, this is not the case for the shallow (DL/B = 1) layer, where the increased soil confinement leads to the development of a stiffer soil column, which offers increased support to the structure. Pairs of identical structures are subsequently analysed, revealing the effect of SSSI on settlement (w) and rotation (ϑ). While its effect on w is beneficial, its effect on ϑ is detrimental, leading to a dramatic increase compared to the single structure. The detrimental effect of SSSI on θ is shown to be a function of the gap (s/B) between the buildings and the depth of the liquefiable layer (DL/B). In the case of the shallow layer, the two structures rotate away from each other. This is not the case of the deeper layer, where they may either rotate away or towards each other, depending on s/B.