新型防沉板基础的地基承载力研究

Bearing capacity of a new type of mudmat foundation

防沉板是水下生产系统中井口、管汇节点、脐带缆等的支撑结构,服役期间需承受V-H荷载空间的强耦合非线性荷载。提出了新型倾斜式裙板防沉板基础型式,倾斜式裙板不仅可以减少海流冲刷对基础下部土体的掏空冲蚀,还可通过调整裙板倾斜角度α适应不同工程对承载力的要求,结合工程设计实例研究了新型防沉板的地基承载性能。结果表明,该新型防沉板基础单向极限承载力随土体强度不均匀性指标А的增加呈线性增长,基础与土体接触面属性对水平向承载力的影响远大于对竖向承载力的影响;防沉板基础V-H荷载空间归一化包络线对土体强度不均匀性指标А在0～10范围内具有普适性,在归一化竖向荷载介于0.5-0.8时Hanson公式高估了防沉板基础的承载力。

Mudmat is commonly used as the foundation of subsea wellhead, pipeline manifold and umbilical cable. In practice, it suffers severe V-H strong coupling nonlinear loads. A new type of slope-skirted mudmat foundation is developed, which can not only reduce the current scour to empty and erode the bottom soil of foundation, but also adjust envelops in V-H loading space by changing the angle α to match different engineering design requirements. The bearing capacity of the new type of mudmat foundation is studied in combination with the engineering design examples. The results show that the ultimate bearing capacity of the new type of mudmat foundation increases linearly with the increase of soil strength heterogeneity index А. Effect of the contact properties between mudmat and soil on the horizontal bearing capacity is more significant than that on the vertical direction. The normalized envelope of V-H load space of mudmat foundation can generally applies to the case that the index А varies from 0 to 10, and the Hanson equation overestimates the bearing capacity of mudmat foundation when the normalized vertical load ranges from 0.5 to 0.8.