陡坡段桥梁基桩桩土相互作用机理及其三维受力分析方法研究

Bridge pile in steep slope will be investigated in this work by conducting situ experiments, model tests, numerical simulation and theoretical approaches, with a discussion on the development of stress and displacement of pile due to different pile-soil interaction mechanisms. This study mainly incorporates: firstly, based on situ experiments and model tests of laterally loaded piles, the pile-soil interaction mechanism of bridge pile will be explored, and a method to determine key parameters will be suggested;secondly, resulting from model tests and numerical simulations under different load combinations, curves corresponding to pile stress, pile displacement, lateral earth pressure and load-displacement will be acquired, load transfer mechanism and failure envelope of piles under load combination in three-dimensional space will be studied; thirdly, by the application of spatial pole element method, three-dimensional stress analysis and calculation model will be established, theoretical calculation method of stress and displacement of pile will be given; lastly, with the comprehensive analysis of results of experiments, numerical stimulation and theoretical calculation, bearing capacity equations of pile will be obtained, and a set of practical three-dimensional stress analysis methods of bridge piles in steep slope will be proposed. The study can provide sound reference to the design of bridge piles in steep slope.

本研究主要以陡坡段桥梁基桩为研究对象，通过现场试验、室内模型试验、数值模拟试验以及理论分析等方式，探讨不同工况下的桩土相互作用机理及桩身内力与位移变化发展规律。具体的研究内容有：首先，通过基桩水平承载的现场与室内模型试验，探讨陡坡段桥梁基桩桩土相互作用机理，提出关键参数取值方法；其次，通过不同组合荷载作用下陡坡段桥梁基桩室内模型试验及数值模拟试验，获得桩身内力与位移、桩侧土压力以及荷载-位移曲线，深入探讨三维空间组合荷载作用下桩身荷载传递规律及基桩破坏包络线（面）；然后，基于空间杆单元法，建立陡坡段桥梁基桩三维受力分析计算模型，提出桩身内力与位移计算的理论计算方法。最后，综合分析试验、数值模拟及理论计算结果，获得基桩的承载力计算公式，提出一套便于工程应用的陡坡段桥梁基桩三维受力分析方法。本研究可为陡坡段桥梁基桩设计提供有力参考。

陡坡段桥梁桩基在我国山区高速公路和铁路建设过程中分布广泛，很有必要对其展开深入系统的研究。本项目主要通过现场试验、室内模型试验、数值模拟试验以及理论分析相结合的方式，研究了陡坡段桥梁桩基的斜坡空间效应、桩土相互作用机理及其破坏模式。首先，通过室内模型试验和现场试验，研究了陡坡段桥梁基桩竖向承载机理，建立了考虑陡坡效应的基桩竖向极限承载力计算公式。其次，基于室内模型试验，研究了不同坡度及水平荷载作用角度下陡坡段桥梁基桩桩土相互作用机理及破坏模式，获得了陡坡地基抗力比例系数m值拟合公式以及相应的p-y曲线。然后，建立了陡坡段桥梁基桩三维数值分析模型，获得了V-H、V-M及H-M等三维空间组合荷载作用下陡坡段桥梁基桩的破坏包络线及其承载力拟合曲线。最后，通过理论分析，提出了考虑斜坡空间效应的陡坡段桥梁基桩简化计算模型及相应的理论计算方法。本项目所得结论可以为陡坡段桥梁桩基建设提供参考和指导。