水-热-力耦合机制下非饱和膨胀土冻胀理论模型研究

This project is closely related to the construction of the high-speed railway in cold regions. Themes, which are to be addressed the damage problem of supporting system in the artificial cutting expansive soil slope along Jilin-Tumen-Hunchun and Harbin-Jiamusi high-speed railways under the seasonally frozen environment, emphasizes the effect of hydro-thermo-mechanical interaction on unsaturated expansive soil during the freezing process. This proposal will explore the frost heave-expansion coupling mechanism of unsaturated expansive soil. Adopting the integrated method of the consulting and investigation, field survey, test detection and numerical simulation, it is expected that hydro-thermo-mechanical coupling model of unsaturated expansive soil in the theoretical framework of crystallization kinetics is proposed on the assumption of non-isothermal condition. Then, this work will be capable of providing the necessary theoretical basis for the design of support system at artificial soil-cutting slope in the expansive soil field under the construction of the high-speed rail under complex environment. And, it can facilitate the objective understanding of the physical processes of hydro-thermo-mechanical coupling effect of the unsaturated expansive soil. It is of great theoretical and practical significance to scientifically improve the design code of support structure of the artificial soil-cutting slope at railway engineering.

紧密围绕我国寒区高铁工程建设的重大需求，聚焦高寒深季节冻土区吉图珲高铁、哈佳高铁现场频发的膨胀土人工路堑边坡支护体系破坏实例，针对冻结过程中非饱和膨胀土水－热－力回馈作用效应问题，着眼非饱和膨胀土冻胀－膨胀牵连机制，采用咨询和现场调查、试验测试、理论分析和数值模拟等相结合的综合研究方法，致力构建基于结晶动力学理论的非等温条件下非饱和膨胀土水－热－力耦合分析模型，进而为复杂冻结环境下高铁建设运行下膨胀土场地人工路堑边坡支护体系设计提供必要的理论基础。这有利于客观认识复杂冻结环境下非饱和膨胀土水－热－力耦合效应的物理过程，对科学完善现行铁路工程人工路堑边坡支护结构设计规程具有重要理论和现实意义。

针对寒区膨胀土场地轨下基础设施病害问题，依托吉图珲高铁、哈佳高铁工程，以沿线深季节冻土区深厚残坡积膨胀土为研究对象，通过研制开放系统单向冻融－胀缩试验装备，开展深季节冻土区膨胀土物理性质、孔隙水温度效应试验与膨胀土冻胀特性试验，揭示了深季节冻土区膨胀土冻结－胀缩牵连效应，提出深季节冻土区膨胀土水－热－变形耦合冻胀模型，开发能够描述膨胀土冻结过程的多物理场耦合分析有限差分程序 FH_ex_Model。研究成果深化了对深季节冻土区膨胀土水－热－变形耦合互馈机制的认识。对深季节冻土区多因素耦合作用下膨胀土场地的工程病害防控具有重要的理论和现实意义。