Shaking table test study on seismic performance of inclined pile foundations in liquefiable soil

Inclined pile foundations are widely used in civil engineering by virtue of sufficient horizontal stiffness, but few studies have touched upon the seismic performance of inclined piles in liquefiable soil. To better understand the performance of the inclined piles in liquefiable soil under earthquake conditions, a series of 1 g shaking table tests of inclined and vertical piles in liquefiable soil were performed. Superstructure-pile-soil dynamic interaction was considered while three types of earthquake waves with different characteristics were selected as the applied earthquake motions. The horizontal acceleration of the superstructure and the pile cap, the rotational acceleration of the pile cap, the total base shear force, and the bending moment of two types of physical models were monitored and analyzed. The results show that inclined piles in liquefiable soil can effectively reduce the horizontal vibration of the superstructure and the pile cap, and the acceleration reduction of the pile cap is about 2.5 times larger than that of the superstructure. Meanwhile, inclined piles can also reduce the total base shear force, and the extent of reduction depends on the input earthquake wave. Besides, the results suggest that the maximum bending moment of inclined piles is located at the pile head, and its value is positively correlated with the amplitude of the earthquake wave, and is affected by the type of the input earthquake wave. Overall, inclined pile foundations show satisfactory seismic performance for a superstructure-foundation-liquefiable soil system, and this study, with a rich amount of data, can serve as an important reference for the seismic design of inclined piles in liquefiable soil.