深季节冻土区高铁膨胀土边坡冻融失稳机制与板桩墙支护体系设计方法

This proposal is motivated by the rapid development of the high speed railway in cold regions in these years. This work is directed against the artificial swelling soil cutting slope and its retaining structure, by relying on Harbin-Jiamusi, Harbin-Mudanjiang and Harbin-Suihua High-speed Rail. This proposal will explore the integrated research method of test detection, in-situ monitoring associated with the theoretical analysis, numerical simulation and criterion analogy. Attention is paid to the seasonal freeze-thaw damage of mesoscopic structure, the degradation of mechanical properties of expansive soils, and the stability of retaining structure under expansion force and frost heaving force. It is expected that through the efforts this proposal will achieve to solve the following problems: (i) Degradation evolution and failure rules for swelling soil’s behaviors; (ii) Failure mechanism of expansive soil slope and its stability under freeze-thaw cycles; and (iii) The easy-use and reliable novel analysis method of the soil pressure calculation method of sheet pile wall. Furthermore, suggestions for improving China’s current design method of retaining wall structure for high speed railway in seasonally deep frozen region will be proposed. The study would greatly help improve understanding of failure mechanism of expansive soil slopes in freeze-thaw cycles and accurately predicting the stability of retaining structure, which is significant in engineering practice as well as in theory research.

基于我国寒区高铁快速发展的时代背景，针对膨胀土人工路堑边坡及其板桩墙支挡体系，依托哈佳、哈牡和哈绥高铁建设工程，采用试验检测、现场监测、理论解析与数值模拟、规范比照等综合研究方法，聚焦季节性冻融环境下膨胀土细观结构损伤及宏观力学特性劣化规律，着眼于膨胀力与冻胀力联合作用下高铁膨胀土边坡支挡体系的稳定性问题，致力研究深季节冻融环境下膨胀土性能劣化演变规律与边坡失稳机制，注重发展便于推广且可靠的板桩墙支挡结构土压力计算方法与稳定性分析理论，并对我国现行规范深季节冻土区高铁膨胀土边坡支挡结构设计方法提出初步改进建议。这对于客观认识深季节冻融环境下膨胀土边坡灾变演化规律与冻融失稳机理，精准分析支挡结构稳定性，科学完善现行铁路工程支挡结构设计规范，无疑具有重要理论和现实意义。

基于我国寒区高铁快速发展的时代背景，针对膨胀土人工路堑边坡及其板桩墙支挡体系，依托哈佳和吉图珲高铁建设工程，采用试验检测、现场监测、理论解析与数值模拟、规范比照等综合研究方法，聚焦季节性冻融环境下膨胀土微细观结构损伤特性，着眼于膨胀力与冻胀力联合作用下高铁膨胀土边坡支挡体系的稳定性问题，致力研究深季节冻融环境下膨胀土性能劣化演变规律与边坡失稳机制，注重发展便于推广且可靠的板桩墙支挡结构土压力计算方法与稳定性分析理论。主要研究工作如下：. (1) 系统开展了冻融膨胀土细微观特性与宏观力学性质试验、考虑温度效应的三轴固结不排水试验、开放系统单向冻胀试验、冻结温度试验，以及DSC试验等，查明了冻融循环作用下膨胀土微细观结构损伤演化规律，提出了描述膨胀土孔隙水冻结过程的结晶动力学模型，建立了考虑温度影响的冻结膨胀土损伤本构模型，创建了非饱和膨胀土水－热－变形耦合冻胀模型。. (2) 针对吉林－图们－珲春高铁延吉段膨胀土路堑边坡，基于饱和非饱和渗流理论，构建了延吉段膨胀土路堑边坡融雪入渗三维数值模型，模拟计算了不同积雪厚度、日气温变化、昼夜大温差等作用下膨胀土路堑边坡的渗流场和整体稳定性。此外，依托哈佳快速铁路宾西段膨胀土路堑边坡工程，开展冻融边坡变形现场监测，探讨冻融循环作用下边坡变形发展演化特征，详细阐述了高寒区膨胀土路堑边坡春融期滑塌机理。. (3) 依托吉图珲高铁典型段膨胀土路堑边坡，建立装配式拱形板－桩墙体系三维有限元模型，分析各开挖工况位移与应力结果，并与直形挡板－桩墙支护性能对比。基于装配式拱形板－桩墙数值模型，探究桩长、桩径、桩间距，以及拱形挡土板矢跨比等重要参数对拱形板－桩墙支护状态中桩前及桩后土压力、桩身内力和桩水平位移的影响，从而得出关键参数对装配式拱形板－桩墙支护性能的影响，并通过正交试验和灰色关联理论分析影响因素的主次顺序，为拱形挡土板－桩墙的设计提供参考建议。在此基础上，提出了确定装配式拱形板－桩墙体系合理桩间距的改进方法，推导了考虑土拱效应的拱形板土压力计算公式。. 研究工作对于客观认识深季节冻融环境下膨胀土边坡灾变演化规律与冻融失稳机理，精准分析支挡结构稳定性，科学完善现行铁路工程支挡结构设计规范，具有重要理论和现实意义。