自升式钻井平台桩靴基础结构设计分析

针对某船厂升降试验场地淤泥质土层较厚,钻井平台升降试验时桩靴入泥过深不易拔出情况,提出用灌注桩基承台作为升降试验的基础结构,并通过有限差分软件建立桩-土-承台相互作用模型,进行承载能力状态下预压工况和组合荷载工况的数值模拟。结果表明:灌注桩承台基础可以满足承载力和沉降要求;承台下L/3(L为桩长)范围土体侧摩阻力最多达到0.5倍极限侧摩阻力,桩端上部2L/3范围内侧摩阻力在0.5～1倍极限侧摩阻力之间;在沉降达到5%D(D为桩径)之前,承台可承担10%～20%的荷载。

Design Analysis for Foundation under Spudcan of Jack-up Platform

The soft clay in the jack-up platform test site for lifting test is thicker,which may cause the spudcan of drilling platform into mud too deep to lift up,so the method of using the bored pile and caps as the foundation to support the spudcan is proposed.Then,the 3D finite difference program is employed to set up the pile-soil-caps interaction model,and the bearing capacity of the pile groups under preloading and combined loading in ultimate state is evaluated respectively.The results indicate that the pile foundation could meet the bearing capacity and settlement requirements;the pile shaft friction of upper part(below the caps for L/3 distance,L means pile length) is not bigger than half of the ultimate side friction,and the shaft friction of lower part is between half and one time of the ultimate side friction;the proportion of load carried by caps is between 10% and 20% before the settlement of pile groups reaches the value of 5%D(D represents the diameter of the pile).