基于剪切位移法的基桩负摩阻力计算

Settlement Calculation of Single Pile's Negative Skin Friction with Shear Displacement Method

在对现有2种常用基桩负摩阻力计算方法进行分析的基础上,探讨了影响桩土间实际负摩阻力的主要因素.进而根据有效应力原理,建立出能充分考虑桩土剪切位移对摩阻力发挥程度影响的基桩负摩阻力计算分段曲线模型,并由此推导出基于荷载传递法的负摩阻力计算基本微分方程,并给出了在不同桩土相对位移条件下基桩负摩阻力计算的分段解析式.在此基础上,引进土体在均布压力作用下沉降的弹性解,从而得到了桩身轴向力、中性点的位置及基桩负摩阻力计算的改进方法.理论与工程实例试验结果对比分析表明,采用该方法所得的桩身轴力随深度的变化曲线与实测曲线吻合良好.

The existing two calculation methods of negative skin friction resistance were analyzed, and the primary influential factors were discussed. Then, based on the effective stress principle and the full consideration of the pile-soil shear displacement, the differential equations of the negative skin friction resistance along the pile shaft were established. Subsequently, the subsection analytical solutions of the negative skin friction resistance under different pile-soil shear displacements were obtained. Lastly, an engineering example was analyzed in the method in combination with the elastic solution, which was obtained in the condition of symmetrical soil-pressure. The calculated results have agreed well with the field measured data. Furthermore, the proposed method can accurately describe the transferring process of the negative skin friction resistance on pile, and the relative parameters can be easily obtained, which are also simple to calculate and feasible for the analysis of the negative skin friction resistance in engineering.