桩坑附近桩靴二次就位过程中滑移载荷研究

自升式平台在遗留桩坑附近就位时，桩靴的滑移风险对于平台结构安全具有重大威胁。基于耦合欧拉?拉格朗日方法，建立了遗留桩坑附近插桩过程的有限元模型，对加载速率和网格密度等进行参数分析，确定了合理的模型参数，并进一步研究了相关参数的影响规律。结果表明，滑移载荷产生的主要原因在于桩靴贯入过程中土体破坏面的不对称；峰值滑移载荷随桩坑坡度、深度和直径的增大而增大；减小桩靴底面坡度可以有效减小桩靴上的滑移载荷。研究揭示了桩坑和桩靴几何参数对滑移载荷的影响机制及其规律，对于深刻认识“踩脚印”问题和有效指导桩坑附近二次就位作业具有科学意义。

Study of sliding loads during spudcan reinstallation close to footprints

The sliding risk during spudcan reinstallation close to a footprint greatly threatens the structural integrity of jack-up units. In this study, a finite element model based on the coupled Eulerian Lagrangian method is proposed to simulate the process of spudcan penetration close to a footprint. Sensitivities of mesh density and loading velocity are evaluated, and the optimal parameters are chosen. With the proposed model, a parametric analysis is conducted. It is revealed that the generation of sliding loads including the horizontal force and bending moment is attributed to the asymmetry of the soil failure plane under the spudcan base, and the peak sliding loads increase with the footprint inclination, depth and diameter. The sliding loads reach the peak at a certain offset distance. The spudcan base inclination has a significant effect on the sliding loads. Reduction of spudcan base inclination results in a decrease of the sliding loads. The present work emphasizes the effects of geometric parameters of both the spudcan and the footprint on the sliding loads, which are of scientific significance to guarantee the safe operation of jack-up reinstallations close to existing footprints.