Research on the Influence of Pile Shoe Insertion and Removal on the Neighboring Three-Cylinder Jacket Foundation in Clay

[Introduction] The construction process of pile insertion and removal for installing offshore wind turbines on mobile platforms is risky, which can easily affect the working performance of adjacent infrastructure, and even lead to its instability and failure. [Method] In order to clarify the mechanism of the influence of pile shoe insertion and removal on adjacent foundation, this paper used CEL large deformation method to simulate the insertion and removal process of similar rectangular pile shoe in homogeneous and heterogeneous clay, and focused on the analysis of the evolution mechanism of additional overturning angle caused by pile insertion process on adjacent jacket foundation; based on the simulation results of large deformation, the influence of soil softening effect on the ultimate bearing capacity of adjacent buckets after pile shoe removal was further studied by using small deformation. [Result] The results show that under the action of pile shoe compaction, the rotational displacement of the three-cylinder jacket foundation will take place, and it will decrease gradually with the increase of net spacing. At the same time, the soil softening caused by compaction will reduce the bearing capacity of adjacent cylinder. [Conclusion] The overturning angle of three-cylinder jacket in heterogeneous soil is larger and the corresponding penetration depth is deeper due to the influence of pile shoe insertion and removal. The affected area of softening area caused by pile shoe insertion and removal is larger in horizontal direction and smaller in depth direction in homogeneous clay. In homogeneous clay, the average strength loss is small, and the horizontal and angular bearing capacity loss of the three-cylinder jacket is small. In homogeneous and heterogeneous clays, the vertical bearing capacity is reduced obviously, and the maximum reduction factor can reach 0.72.