基于桩-土非线性作用的缺陷桩竖向承载特性分析

Analysis of Vertical Bearing Characteristics of Defective Pile Based on Nonlinear Pile-soil Interaction

为评价桩身缺陷对基桩竖向承载性状的影响,提出一种考虑非线性桩-土相互作用的缺陷桩简化计算方法,重点分析桩身裂隙和缩径段长度、埋深等对桩身内力和变形的影响。结果表明,桩身裂隙使基桩Q-s曲线中部产生反弯段,裂隙段埋深越大反弯点位置距离原点越近,裂隙长度越大位移陡降现象越明显;桩身缩径主要影响基桩的竖向刚度和极限承载力,缩径桩Q-s曲线形状与正常桩类似,但桩身轴向应力在截面变化位置发生突变。简化分析方法为缺陷桩竖向承载性状的定量分析提供一条新途径,分析成果可为基桩缺陷判别和承载力评定提供参考。

In order to evaluate the influence of pile defects on the vertical bearing behavior of foundation piles, a simplified calculation method for defective piles that takes into account nonlinear pile-soil interaction is proposed. The analysis focuses on the pile body cracks, the length of the reduced diameter section, and the buried depth, and their influences on pile internal force and deformation. The results show that the cracks in the pile body cause a reverse bending section in the middle of the Q-s curve of the foundation pile. The deeper of the crack section, the closer the reverse bending point to the origin, the larger the crack length, the more obvious the steep drop in displacement. The shrinkage of the pile body mainly affects the vertical stiffness and ultimate bearing capacity of the foundation pile. The shape of the Q-s curve of the reduced pile is similar to that of a normal pile,but the axial stress of the pile body changes abruptly at the position where the diameter changes. The simplified analysis method provides a new way for the quantitative analysis of the vertical bearing behavior of defective piles, and the analysis results can provide a reference for the foundation pile defect identification and bearing capacity evaluation.