Effect of spatial variations in relative density for dense sand on seismic behavior of the seawall pile foundation based on centrifugal shaking table experiments

抄録

Physical properties of soil ground are generally varying spatially. However, in the seismic design of structures, especially nuclear power plants, the physical properties are considered conservatively even though their spatial variation is observed at the ground surrounding the foundations. In this study, to clarify the effect of spatial variations of relative density (Dr) of sand on the seismic behavior of the seawall pile foundation, two cases of the centrifugal shaking table experiment under centrifugal acceleration of 50 G were conducted. They had different spatial variations composed of two relative densities of sand; one was Dr = 103% with 80% of the volume occupation ratio, another one was Dr = 70%, which liquefaction strength ratio was the half that of Dr = 103%, with 20% of the volume occupation. Based on the experimental results, it was found that the effect of the different arrangements of the sand with Dr = 70% were negligible because similar dynamic response of excess pore water pressure, horizontal displacement of the seawall, and bending strain of the seawall pile foundation were observed in both cases.