Experimental study on the seismic response of foundations : impact of coral silt location on structural behavior during seismic events

Abstract

In coral reef hydraulic reclamation projects, particle sorting creates interbedded foundations composed of coral sand and silt within the reef structure. This study examined the seismic response of such foundations with varying positions of the coral silt layer using 1 g shaking table tests. The results showed that a coral sand foundation with the silt layer positioned in the middle exhibited greater overall stiffness during seismic activity compared to one with the silt at the bottom A middle located silt layer also alters the distribution of excess pore water pressure: the depth-distribution curve beneath the superstructure displayed a distinct turning point at the silt layer, with a significant increase in pressure within the silt and a reduction in the upper layers. At a peak ground acceleration (PGA) of 0.15 g, the middle silt layer substantially reduced both horizontal displacement and superstructure settlement, with settlement decreasing by 70.1 % compared to foundations with the silt at the bottom. In both configurations, shear strain decreases with depth, underscoring the influence of overburden pressure.