Centrifuge modeling of seismic foundation-soil-foundation interaction on liquefiable sand

Abstract

Liquefaction-induced settlement and bearing capacity failure have been reported as leading causes of damages in shallow foundations during earthquakes. Previous studies of this problem have mainly focused on the performance of isolated shallow foundations. In urban areas, however, foundations are generally located in close proximity. In this study, three series of centrifuge tests were conducted to investigate the effect of foundation-soil-foundation interaction (FSFI) on the seismic and post-seismic settlement of shallow foundations on saturated sand. Two rigid foundations with different surcharge loads (as heavy and light foundations) were placed with different spacing. Multiple shaking events were applied to achieve different extents of soil liquefaction. The results indicate that significant part of foundation settlement occurred before soil reconsolidation. Furthermore, the time period after shaking, wherein excess pore water pressure sustains, plays an important role in the total settlement of foundations. The acceleration responses experienced by the foundations were significantly larger than those observed in the free-field. The heavy foundation fluctuated more strongly than the light one. Moreover, adjacency considerably affected the seismic response of foundations whereas stronger acceleration response on the ground level was observed for the closer cases. The Clear asymmetric settlement was observed for the adjacent foundations. It is demonstrated that settlement of foundations not only is dependent on foundations' proximity but also is a function of shaking intensity. Influence of foundations' spacing on the generation-dissipation mechanism of excess pore water pressure (EPWP) and liquefaction extent was described by the time-dependent contours plotted by interpolation of the recorded data.