为评估海底浅基础服役过程的承载力时变规律,推导了预载作用下黏土海床完全固结后的不排水抗剪强度分布,利用滑移线法给出了应力特征线方程并求解出浅基础固结承载力,研究了预载比、土体不均匀性、有效内摩擦角和基础尺寸对浅基础固结承载力的影响.结果表明:浅基础固结承载力的相对增长幅度和预载比近似呈线性关系,由土体不均匀因子和有效内摩擦角共同决定,不受基础尺寸的影响.通过与水土耦合有限元分析结果进行比较,对所提方法的准确性进行了严格的验证,表明了该方法的有效性.最后,根据有限元结果分析了滑移线解的误差来源,发现孔压计算差异是导致固结承载力预测结果产生误差的主要原因.该滑移线解可快速准确地预估浅基础固结承载力的增长规律,为海底浅基础的优化设计提供重要参考.

To evaluate the bearing capacity evolution of subsea shallow foundations during operation, an undrained shear strength distribution of clay seabed following full consolidation due to preloading was deduced. The characteristics method was used to derive the stress characteristics equation and to evaluate the consolidated bearing capacity of shallow foundations. The influence of preloading ratio, soil inhomogeneity, effective internal friction angle, and foundation dimension on the consolidated bearing capacity of shallow foundations was investigated. The result shows that the relationship between the relative gain in the consolidated bearing capacity of shallow foundations and the preloading ratio is approximately linear. Meanwhile, the relative gain in consolidated bearing capacity is jointly determined by soil inhomogeneity and effective internal friction angle and is not affected by the foundation dimension individually. The accuracy and effectiveness of the proposed method were verified by comparing it with the results of soil-water coupled finite element analysis. Finally, possible errors between the characteristics solution and finite element model (FEM) results were analyzed. It was found that the discrepancy in the pore pressure calculation was the main reason for the disparity in the prediction of consolidated bearing capacity obtained by two methods. This characteristics solution can quickly and accurately predict the growth of consolidated bearing capacity of shallow foundations, which provides important reference for the optimal design of subsea shallow foundations.