Abstract: Post-grouting technique has been applied to the infrastructure construction of coral reefs, but there has been little research about the horizontal bearing behavior of post-grouted piles in calcareous sand. Based on the case of post-grouted piles in calcareous sand under horizontal load, the horizontal bearing rule of ungrouted and post-grouted piles in calcareous sand was studied comprehensively by laboratory model tests, and the influence of post-grouting on the horizontal bearing behavior of pile in calcareous sand was investigated. The infiltration and diffusion of injected cement grout in calcareous sand were analyzed through soil excavation of post-grouted piles. The results show that the lateral critical load and the lateral ultimate load of post-grouted piles in calcareous sand are significantly improved compared with those of ungrouted piles under the same condition. Besides, the ability to control lateral deformation under grouting is better than that of piles without grouting. The proportional coefficient m of the lateral soil resistance coefficient of ungrouted and post-grouted piles gradually tends to be consistent with the increase of the lateral displacement of the pile head, and the bending moment of pile shaft and the soil pressure around piles are mainly concentrated in the upper part of the pile and soil. The lateral bearing capacity of piles is greatly affected by the upper level of soil, and grouting at the pile side can effectively increase lateral bearing capacity by improving the upper soil physico-mechanical properties. In addition, according to the soil excavation analysis, the cement grout injected at the pile side is mixed with calcareous sand to form a stable structure of cement stabilized soil. This provides the improved lateral bearing capacity of the pile in calcareous sand.

Key words: calcareous sand, post-grouted pile, model test, lateral bearing capacity, cement stabilized soil