Test Analysis of Post-Grouting Improvement Coefficient for Cast-in-situ Pile in Thick Sand Layers

The experience of the post-grouting effect for cast-in-situ pile in thick sand layer is limited presently. Based on the static pile load test in a project of Tongzhou New Town, Beijing, the bearing capacity of single pile after post-grouting and without post-grouting was analyzed and compared, and the efficiency of post-grouting technology in this thick sand layer site was studied. It shows that post-grouting can effectively reduce settlement. Compared with the test results of pile without post-grouting, the comprehensive improvement coefficient of post-grouting can reach 2.22. Compared with the calculated value based on geotechnical report for bearing capacity of non-post-grouting pile, the comprehensive improvement coefficient of post-grouting for cast-in-situ pile is about 2.53～3.57. This study can provide reference for the subsequent design of pile foundation with similar geological conditions.