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将抗拔桩侧阻力分解为与桩侧正压力不相关的桩-土黏结强度pc、与桩侧有效正压力成正比的摩擦力sF两部分,采用摩擦定律计算摩擦力sF。基于轴对称条件,假定土体为半无限弹性体,以Mindlin公式积分计算分析极限平衡状态下桩-土共同作用,依据平面应变条件下柱状孔扩张的弹性力学解建立桩-土界面位移协调方程,推导出抗拔桩极限平衡方程,给出了求解方法及计算参数确定方法。该方程能反映桩与土的材料特性、桩体尺寸、桩顶埋深、群桩效应、卸荷效应等多因素对抗拔桩极限承载力的影响。结合海上风电大直径超长抗拔钢管桩足尺试验进行验证。对比分析结果表明,该方法计算的抗拔极限承载力与实测值接近,计算精度远高于现行规范推荐方法,其结果可为工程应用及抗拔桩承载力机制研究提供参考。
The lateral resistance of the pile is decomposed into two parts: the pile-soil bond strength pc which is not related to the positive pressure on the pile side and the friction force sF which is proportional to the effective positive pressure on the pile side. The friction law sF is calculated by the friction law. Based on the axisymmetric conditions, assuming that the soil is a semi-infinite elastic body, the pile-soil interaction under the limit equilibrium state is calculated by Mindlin’s integral method. The displacement-coordination equation of pile-soil interface is established based on the elastic mechanics solution of the cylindrical hole expansion under the plane strain condition , The ultimate equilibrium equation of anti-pull piles is deduced, and the solution method and the determination method of calculation parameters are given. The equation can reflect the influence of pile-soil material characteristics, pile size, pile top depth, pile-group effect and unloading effect on the ultimate bearing capacity of anti-pull pile. Combined with offshore wind large diameter pull-out pipe pile full-foot test to verify. The results of comparative analysis show that the ultimate tensile strength calculated by this method is close to the measured value and the calculation accuracy is much higher than the current recommended method. The results can provide references for engineering application and bearing capacity of tension pile.