Full-scale field test study of bearing characteristics of post-grouting pile for offshore wind turbines

Full-scale load tests were conducted on a combined steel pipe and bored pile foundation used for offshore wind turbine in Fuqing Xinghua Bay. Due to the complex geological conditions of the project, lengthening the bored pile will cause it to exceed the steel pipe pile so much that there are construction risks such as collapsed holes, hence, combined tip-and-side post-grouting was used to improve the bearing characteristics of the pile foun-dations. The results of double-level O-cell bi-direction tests before and after grouting on test pile SZ32 are re-ported. Comparing the test results before and after grouting shows that post grouting can significantly enhance the bearing capacity of the pile foundations. Furthermore, the relative displacement required to mobilize the shaft resistance of the test pile is significantly reduced by the post grouting craftwork. Additionally, the core samples obtained from the coring tests showed that the cement grout was distributed from 0.5 D below the pile tip to 5.3 D above the pile tip, respectively. Finally, the results could be applied to similar foundation design used in offshore wind turbine.