New Mechanism-Based Design Approach for Spudcan Foundations on Single Layer Clay
New Mechanism-Based Design Approach for Spudcan Foundations on Single Layer Clay
复制标题
DOI：
10.1061/(asce)gt.1943-5606.0000054
复制
发表时间：
2009-09-01
影响因子：
3.9
通讯作者：
Randolph, Mark F.
中科院分区：
文献类型：
--
作者：
Hossain, Muhammad Shazzad;Randolph, Mark F.
海上移动的钻机桩靴基础是大型碟形基础，可深入软质沉积物数十米。穿透深度通常通过考虑不同深度处的原位基础并遵循传统承载力方法来预测，以评估估计承载力与施加载荷相匹配的深度。然而，潜孔桩的几何形状及其渐进式贯入模式导致土壤破坏机制与陆上实践中的相关机制明显不同。基于离心模型试验和大变形有限元分析，提出了一种新的合理设计方法，用于评估单层粘土中的锚定贯入度。该设计方法考虑了土壤中不断变化的破坏机制，从浅贯入处的空洞形成和表面隆起开始，逐渐转变为土壤在罐内的回流。详细的有限元参数研究探讨了归一化强度，强度不均匀性，和drocan基地粗糙度的相关范围，与离心模型试验数据验证的结果。以承载力系数的剖面形式给出了贯入响应曲线，形成了无量纲设计图表，沿着有简化的表达式，便于实际应用。与SNAME设计规范中建议的方法进行比较表明，迫切需要更新当前的做法。
Spudcan foundations for offshore mobile drilling rigs are large saucer-shaped foundations that can penetrate several tens of meters into soft sediments. The penetration depth is typically predicted by considering a wished-in-place foundation at different depths and following traditional bearing capacity approaches to assess the depth at which the estimated capacity matches the applied loading. However, the geometry of the spudcan and its progressive mode of penetration lead to soil failure mechanisms that differ markedly from those relevant to onshore practice. This paper presents a new rational design approach for assessing spudcan penetration in single layer clays based on a study combining centrifuge model testing and large deformation finite-element (FE) analysis. The design approach takes account of the evolving failure mechanisms in the soil, which start with cavity formation and surface heave at shallow penetration, gradually transforming to backflow of soil over the spudcan. A detailed FE parametric study has explored the relevant range of normalized strength, strength nonhomogeneity, and spudcan base roughness, with results validated against centrifuge model test data. The penetration response curves are presented in terms of profiles of bearing capacity factors, forming nondimensional design charts along with simplified expressions for convenient use in practice. Comparisons with approaches suggested in the SNAME design code suggest an urgent need to update current practice.