考虑桩-土体系渐进破坏的单桩承载特性研究

针对目前桩基承载特性确定时未考虑桩-土体系渐进变形过程的现状,采用现场试验和理论分析等手段对考虑桩-土体系渐进破坏的单桩承载特性展开研究。首先,利用现场试验数据对侧阻和端阻的软化特性展开深入探讨,提出了侧阻和端阻软化模型,明确了模型中各参数取值方法,并验证了其合理性。同时,根据提出的侧阻和端阻软化模型,建立了一种可考虑桩-土体系渐进破坏的单桩承载特性的迭代算法。算例分析表明,计算获得的破坏性单桩承载特性与实测值有较好的一致性,且可反映侧阻和端阻的破坏特性。实际工程中,结合单桩承载特性分析算法,可根据单桩的实际受力特点灵活选用不同形式的侧阻和端阻荷载传递函数来分析不同桩顶荷载水平下的单桩受力特性。

Analysis of bearing behavior of a single pile considering progressive failure of pile-soil system

In light of that the progressive deformation of pile-soil system is not taken into account in the determination of bearing behavior of pile at present, field test and theoretical analysis are used to analyze the bearing mechanism of single pile considering progressive failure of pile-soil system. Firstly, the skin friction degradation and end resistance softening are analyzed using field test results; and then the softening models of skin friction and end resistance are proposed. Furthermore, determinations of the parameters related to the softening model of skin friction and end resistance are presented, and the reliability of the proposed models is demonstrated. As to the bearing behavior of a single pile considering progressive failure of pile-soil system, a highly effective iterative computer program is developed using the proposed softening model. Comparisons of the load-settlement response demonstrate that the proposed method is generally in good agreement with the field-observed behavior, and can assess the failure characteristic of skin friction and end resistance. For practical purposes, different load transfer functions of skin friction and end resistance can be selected in the proposed iterative computer program to capture a single pile response at different loading levels.