Experimental Analysis of Pile Group in Liquefying Soil Under a Ground Motion Using Centrifuge Test

This study is aimed to conduct a series of grouped-model piles (2x2) using centrifuge shaking table tests with the acceleration of 80 g and to simulate seismic dynamic responses of the grouped-piles embedded in liquefiable sandy soil subjected to different magnitudes of earthquake loading. The grouped-piles testing connected with a pile cap are used to support 4 sets of model dry storage tank. Test variables including elevations of pile cap, elevations of ground water, as well as dry sand and saturated sand beds all are reported and compared. Strain gauges and accelerometers at different depths densely instrumented in the piles and the surrounding soils provide valuable information for examining their evolution at various degrees of liquefaction. Test results illustrated that the magnitudes of bending moment along pile depths would increase with the increases of base shaking. The lowest bending moments are gained at the grouped-piles with the pile cap embedded in the dry sand bed; correspondingly, the largest bending moments are measured for the grouped-piles with the pile cap embedded in the saturated sand bed with the water table at the surface.