Shaking table test on rock-socketed piles in saturated sand foundation considering the effect of karst caves

Karst landform is a major unfavorable geological condition that significantly impacts the pile foundation in bridge engineering. The karst caves may cause foundation failure and induce severe damage to pile foundation under seismic action. Currently, there is a limited number of studies on the seismic dynamic response rules and mechanical properties of rock-socketed piles in karst areas. In this paper, the shaking table test on the seismic response of penetrated rock-socketed piles in saturated sand foundation considering the effect of karst caves is carried out, and a large-sized stratified suspended shear box is adopted to simulate the soil boundary effect. The effects of ground motion intensity, karst cave height, and foundation state on the seismic dynamic strain response of rock-socketed piles are explored. Test results show that the peak dynamic strain of the penetrated rock-socketed pile in the saturated sand layer initially increases and then decreases from bottom to top of the pile, and its maximum peak strain response occurs in the middle of the pile. The increase of karst wave height causes the penetrated rock-socketed pile in the saturated sand layer to become susceptible to premature failure in the middle. With the increase of earthquake intensity, the effect of karst caves on the response becomes weaker. However, in dry sand foundation, the peak strain of the pile is small in the middle and large value occurs at pile ends, which indicates that the seismic failure modes of pile foundation in dry and saturated sand foundation are significantly different.