具桩靴自升式钻井船插桩过程有限元模拟研究

Study of FEM simulation in spudcan penetration process for jack-up platform

在评价具桩靴自升式钻井船的插桩深度及承载力时,包括浅基础、桩基础在内的多种计算方法均有各自的适用条件和局限性。应用有限元数值模拟方法,分别研究了桩靴在均质黏土和均质砂土中贯入一定深度时的地层响应情况,取得了桩靴贯入过程中地基土破坏形式、荷载影响深度、不同公式的适用性等多方面认识。在均质黏土中,随着插桩深度的增加,地基土先后经历了整体剪切破坏、局部剪切破坏、冲剪破坏三种破坏形式;在均质砂土中,地基土的破坏形式主要表现为整体剪切破坏。插桩荷载的影响深度约为3倍桩靴截面宽度。浅基础公式的计算结果与有限元模拟成果更为接近。

In evaluating penetration depth and bearing capacity for jack-up with spudcan,each formula either for shallow foundation or for pile foundation has its own applicable conditions and limitations. FEM simulation was applied to study the stratum response of spudcan penetration in homogeneous clay and sand. Finally the foundation failure mode,load influence depth and applicability of each bearing capacity calculation formula were recognized.In homogeneous clay,the foundation failure mode develops from general shear failure and local shear failure to punching shear failure with the increasing of penetration depth,while in homogeneous sand it mainly shows general shear failure. The influence depth of spudcan load is mainly in the depth of 3. 0 B. The calculation results by shallow foundation formulae are closer to the result of FEM simulation in homogeneous soil.