分层土体静压桩桩端力学性状及土体破坏宏细观机理研究

Investigation on the end resistance and soil failure mode of jacked pile tip can reveal the actual physical mechanism of jacked pile driving process,which is the key of resolving pile-soil interaction and optimizing displacement-control in pile design theory. By means of the model test and numerical analysis of pile jacked into layered soil, the project aims to uncover the behaviors of end resistance with penetration depth of pile and the distribution characteristics of stress-strain of soil around pile end under different influence factors such as soil features,L/D,pile ending forms, meanwhile, establish respective regression equation by the analysis of the soil plugging effect of open-ended pile and the scale effect of pile end. Moreover,the macroscopic and microscopic parameters of soil around pile end are studied to disclose evolution mechanism of soil around pile end and define the sliding failure plane of pile end. Finally, the relationship between the macro mechanical responses and soil microscopic parameters are discussed, and design formulas of pile end bearing are also proposed and established. The research results will contribute to improve the existing design theory of pile foundation, and it has an important practical application value for engineering.

为揭示静压沉桩的真实物理机制，应重点研究沉桩过程中桩端阻力工作性状和桩端土体破坏机理，这是解决桩基设计中桩土共同作用和优化沉降控制的关键。本项目拟通过在层状地基中进行静压桩模型试验以及离散单元数值模拟研究，揭示不同影响因素下（土层性状、桩长径比及桩端形式）桩端阻力随贯入深度的变化规律及桩端土体应力分布特征，并对桩端尺寸效应及开口管桩的土塞效应进行分析，建立相应的函数方程。此外，对沉桩过程中不同工况下桩端土体宏细观参数变化开展研究，揭示桩端土体破坏演化机制，确定合理的桩端滑动破坏面。最终，明确桩土宏观力学响应与土体细观参数的相关性，提出并建立合理的桩端承载力计算公式。研究成果将为桩基设计提供理论依据，具有重要的工程应用价值。

为揭示静压沉桩的真实物理机制，应重点研究沉桩过程中桩端阻力工作性状和桩端土体破坏机理，这是解决桩基设计中桩土共同作用和优化沉降控制的关键。本项目拟通过在层状地基中进行静压桩模型试验以及离散单元数值模拟研究，揭示不同影响因素下（土层性状、桩长径比及中桩端形式）桩端阻力随贯入深度的变化规律及桩端土体应力分布特征，并对桩端尺寸效应及开口管桩的土塞效应进行分析，建立相应的函数方程。此外，对沉桩过程中不同工况下桩端土体宏细观参数变化开展研究，揭示桩端土体破坏演化机制，确定合理的桩端滑动破坏面。最终，明确桩土宏观力学响应与土体细观参数的相关性，提出并建立合理的桩基承载力计算公式。研究成果将为桩基设计提供理论依据，具有重要的工程应用价值。