中文摘要：

运用有限元分析方法研究了前期作业遗留桩坑对自升式钻井平台滑移风险的影响,提出了降低滑移风险的对策,并进行了实例分析。考虑流体在孔隙结构中的渗流、滑动摩擦接触以及材料与几何非线性,建立了桩-土相互作用的流固耦合有限元模型,通过数值模拟结果与已发表文献中实验结果的对比,验证了模型的可靠性。利用建立的模型分析了前期作业遗留桩坑影响下的桩基土体破坏过程、运移形式及遗留桩坑对桩-土相互作用的影响,结果表明：插桩初期遗留桩坑底部与桩靴底部出现塑性破坏区域,然后破坏区域随着压载的增加不断增大,直至形成连续滑移面;桩靴周围土体的运移形式随着桩靴与遗留桩坑距离的增大出现明显变化;随着桩靴-遗留桩坑中心距的增大,峰值水平滑移力先增大再逐渐减小。在最终位置插桩前以适当的距离和深度进行试踩可有效降低平台滑移风险。

英文摘要：

Analysis on the sliding risk of jack-up platform re-installation close to the existing footprint is conducted with finite element method. An effective countermeasure to reduce the sliding risk is suggested and an example analysis for an existed jack-up platform re-installation in a typical block with two layer soil within design driving depth in China sea area is carried out. Taking into consideration fluid seepage in pore structure, sliding contact friction, and the material and geometric nonlinear properties, a fluid-solid coupling finite element model for the spudcan-soil interaction is constructed. By comparing the numerical simulation result with the experimental result published in the literature, the reliability of the finite element model is verified. With the model, the failure process, the movement pattern of foundation and the spudcan-soil interaction under the impact of the footprint are analyzed. The study shows： in pitching pile the plastic failure zone appears at the low corner close to the spudcan first, then the area beneath the spudcan, and the plastic area becomes larger to form a connecting region finally as the loading increases continuously; the migration pattern of soil around the spudcan changes sharply with the distance between the spudcan and the footprint increasing; at the same time the peak value of the horizontal sliding force increases first then decreases gradually. In the final pitching pile position, ‘stomping＇ in advance in appropriate distance and depth can reduce the sliding risk of a jack-up platform re-installation effectively.