Shaking table tests on efficiency of improvement of X-section piles against lateral spreading

Lateral spreading often occurs in liquefiable sloping ground during earthquake, which causes severe damage to the nearby constructions. Installing piles into sloping ground has been proven to be effective in reducing the lateral displacement. The X-section cast-in-place concrete pile (XCC pile) can save material usage compared with the conventional circular pile. Besides, its special section shape has better effect in restraining the lateral flow of liquefied sand than circular section. A series of 1g shaking table tests are conducted to verify the efficiency of improvement of XCC piles against liquefaction-induced lateral flow. The mitigation efficiencies of XCC piles and circular pile are compared. Besides, the effects of pile arrangement pattern, orientation of X-section and special section are taken into consideration. The results suggest that the XCC pile can restrict the lateral displacement of liquefied sand, compared with the unimproved case, and the lateral displacement and flow area in XCC pile-improved case are reduced by 38% and 50%, respectively. With the same material usage, the mitigation efficiency of XCC piles is obviously higher than that of circular pile and the flow area is reduced by 20%. The triangular pile arrangement pattern is more effective in restricting the lateral spreading than square pile arrangement pattern. The mitigation efficiency of different orientations of XCC piles depends on the effective section length perpendicular to the direction of lateral flows. The special section effect of XCC piles can increase the mitigation effect by 5%~18%.