冻结粘土介质空间变异特性及其结构随机热力动态演化机制

The spatial variability of frozen clay leads to the randomness of thermodynamic characteristic of artificial freezingcurtain, which make the structural system have an unexpected deviation and unpredictability. It will affect the safety of design and construction for freezing method. Taking the reliability evaluation of clay freezingcurtain as the research background, this project will take the stochastic hydro-thermal-mechanical interaction process of frozen clay as the key scientific issue. Based on the experimental result of the correlation and variability of the basic thermodynamic parameters, an evaluation index for the stochastic behavior of frozen clay medium will be proposed. According to the macro micro statistical distribution test of stochastic moisture migration, frost heave and temperature in the process of freezing, the interaction relationship of stochastic moisture, temperature and frost heave will be discussed. After carrying out the triaxial test for uniform temperature and gradient temperature, the constitutive model of frozen clay will be developed. Based on all test results and interaction relationship, a stochastic hydro-thermal-mechanical dynamic coupling model of frozen clay will be established. After compiling the coupling stochastic finite element program, a numeric simulation platform will be developed, and the prediction model of stochastic thermal-mechanical dynamic evolution of artificial freezingcurtain will be obtained. This project has important scientific significance and practical value in understanding the spatial variability of frozen clay, the improvement of stochastic multi-field coupling theory as well as stability and security of freezingcurtain.

冻结粘土材料的空间变异性导致人工冻结帷幕的热力学性质存在随机性，进而对结构系统产生较大的、意想不到的偏差或不可预知性，影响冻结法设计与施工的安全。本项目以粘土层人工冻结帷幕的可靠性评价为研究背景，紧紧围绕冻结粘土随机水热力相互作用过程这一关键科学问题，开展基本土性参数的相关性与变异性试验研究，建立冻结粘土介质随机场特性评价指标；进行冻结过程中随机水分迁移、冻胀及温度的宏微观统计分布测试，探索随机水分、温度及冻胀之间的相互作用关系；开展均匀温度与梯度温度的三轴加、卸载试验，发展冻结粘土本构模型；综合所得试验结果与作用关系，构建冻结粘土随机水热力动态耦合模型，研制耦合随机有限元实施程序，开发数值仿真平台，建立耦合作用效应下冻结帷幕随机热力动态演化预测模型。本项目的实施对促进冻土材料变异性与随机多场耦合基础理论的发展、指导人工冻结帷幕的稳定与安全具有重要科学意义和实践应用价值。

冻结粘土材料的空间变异性导致冻土工程结构的热力学性质存在随机性，进而对结构系统产生较大的、意想不到的偏差或不可预知性，影响冻结设计与施工的安全。本项目以冻结粘土介质空间变异特性及其结构随机热力动态演化机制为研究对象，通过实验室试样试验、理论分析、随机有限元数值技术与现场实测相结合的研究手段，阐明了冻结粘土参数变异性演化规律与随机热力动态演化机制，建立了冻结粘土随机热力演化过程理论模型，科学预测了冻结粘土随机热力学特性动态演化规律与变异性特征。项目按计划完成了：(1)冻结粘土介质空间变异性特征研究，包括：①进行了冻结粘土不确定性热力参数的随机性描述，②计算了冻结粘土参数随机场的数字特征，③提出了二维六节点三角形单元局部平均法及三维四面体单元局部平均法；(2)冻结粘土随机热学特性动态演化规律研究，包括：①推导了冻结粘土温度场随机有限元分析列式，②建立了冻结粘土温度场随机有限元理论模型，③开发了冻结粘土温度场随机有限元实施程序；(3)冻结粘土随机力学特性动态演化规律研究，包括：①推导了冻结粘土本构关系的详细矩阵形式，②建立了冻结粘土应力变形随机有限元理论模型，③开发了冻结粘土应力变形随机有限元实施程序。本项目已发表学术论文8篇（SCI7篇、EI1篇），申请国家发明专利4项，出版学术专著1部，项目负责人被评为中国矿业大学岩土工程学科优秀青年骨干教师。本项目的主要性贡献在于：将随机场理论及随机有限元法引入到冻土力学与工程领域，考虑冻土区土体热力学参数空间变异性及热边界条件随机性特点，对冻结粘土介质空间变异性特征、冻结粘土随机热力特性动态作用过程及冻结粘土随机热力特性动态演化规律问题进行了系列深入研究，为冻土工程热力稳定性评价提供了新思路。