Centrifugal model test of post-grouting pile group in loess area

Abstract

In this paper, based on the in-situ post-grouting single pile of the Wuqi-Dingbian Expressway in China, the bearing performance of the post-grouting pile groups in loess area were studied with the use of the centrifugal model test. Taking into consideration pile spacing and number of piles, nine working conditions of single pile, 2 × 2 pile group with different pile spacing and 3 × 3 pile group were designed. The settlement, ultimate bearing capacity, pile side resistance, and end resistance ratio of pile groups with different pile spacing and number of piles before and after grouting were compared and analyzed. Finally, based on the change in the group efficiency obtained before and after grouting through the model test, the group efficiency of non-grouting pile groups in code was modified and applied to the calculation of the ultimate bearing capacity of the grouting pile groups. The results show that the group efficiency will decrease after grouting, and the bearing capacity of grouting pile groups increases gradually with the increase of pile spacing, and reaches the maximum when the pile spacing is 5d. The proposed bearing capacity calculation method of grouting pile group was validated by the model test results, and the calculation results generally agree with the model results, which is valuable for pile foundation designs.