【作者】 程知言；

【导师】 张可能； 曾祥熹；

【作者基本信息】 中南大学 ， 地质工程， 2003， 博士

【摘要】 在对人工地层冻结研究现状分析讨论的基础上，本文以上海延安东路隧道地层冻结为背景，应用室内试验、现场实测、理论分析和数值模拟的综合方法，对饱和软土地区的浅表隧道多冷源冻结的温度场、应力场、水分场耦合原理、规律及相关参数进行了较系统的研究，主要研究内容如下： 首先，针对理论研究和冻结工程的实际需要，对上海地区三种饱和软土的起始冻结温度、低温土体未冻水含量、含冰量、冻、融土的比热、土体导热、导温系数、低温土体的无侧限抗压强度、三轴剪切强度、弹性摸量及泊松比等指标进行了室内试验。分析了三种软土的起始冻结温度及冻、融土导热、导温系数的影响因素、低温土体未冻水含量、弹性模量、泊松比与温度的定量关系；研究比较了封闭系统中上海三种软土的冻胀特性；讨论了低温土体无侧限抗压强度、三轴剪切强度的变化规律。 其次，归纳、整理了上海延安东路隧道冻结工程的温度、应力、地表变形和土体分层位移现场实测数据。分析了土体冻结过程中温度场、应力场变化及多冻结管供冷的相互干涉、影响规律，并对水分迁移、孔隙水相变和土体变形与温度场、应力场的耦合规律进行了分析。 第三，在对室内试验和现场实测结果研究的基础上，分析了土体冻结过程中温度场、应力场、水分场耦合原理，并按照冻土体形成发展过程，首先建立了单一冷源冻结轴对称温度、应力、水分场耦合模型；接着利用势场的迭加原理，将单一冷源情况的三场耦合问题推广到多冷源情况的三场耦合；最后根据能量守恒平衡方程、应力平衡方程、质量守恒平衡方程、几何方程、物理方程、初始及边界条件，解出了单一冷源平面轴对称问题的解析解。 最后，在应用Galerkin加权余量法分析的基础上，同时做了一些简化和假设，得到了浅表隧道多冷源冻结情况的温度场、应力场、水分场耦合数值解；利用编制的有限元程序对冻结过程进行了计算机模拟，得到了与现场实测基本一致的结果。更多还原

【Abstract】 Based on the research achievements of the artificial ground freezing in the past, combined with the ground freezing engineering practice of the tunnel of Yan’an Dong road, Shanghai, and by a series of methods including laboratory tests, site observation, theoretical analysis and numerical simulation, author has systematically studied the coupling mechanism and law of three fields ( temperature, stress, moisture migration) and got some important results about soft soil and freezing processFirstly, according to the requirement of theoretical study and engineering practice, the physical and mechanical properties of three kinds saturated soft clay in Shanghai area in the frozen and unfrozen conditions have been tested in laboratory. The influencing factors of initial freezing temperature of soft clay which is in natural condition and the thermal conductivity, thermal diffusion ratio of frozen and unfrozen clay are analyzed. The quantitative relationship between the temperature and the unfrozen water content, elastic modulus and Poission’s ration are obtained. The frost heave behaviors of the soft clays are also discussed. By means of the unconfined compression test and tri-axial shear test, the strength variation law of frozen clay is studied.Secondly, by means of the systemizing to the site surveying data oftemperature, stress, surface deformation and soil layers displacement, the variation law of temperature field and stress field and the interference and effect of multi-freezing pipes are analyzed. According to the distribution characteristics of soil layers and installing place and depth of freezing pipes, the coupling properties of temperature, stress, the phase transition of pore water and ground deformation are studied.Thirdly, according to the development of the frozen soil, the coupling model of single freezing pipe of axial symmetry of temperature field, stress field and moisture migration is put forward firstly. Then, by means of the progressing principle of potential field, the coupling model of temperature field, stress field and moisture migration which is under the condition of the multi-freezing pipes is extended. At last, the energy balance equation, stress balance equation, quality balance equation, geometric equation, physical equation, initial and boundary conditions etc are adopted to give the analytic solution to the problem of plane axial symmetry of single freezing pipe.At last, based on the analysis of Galerkin finite element method and some simplification and hypothesis, the numerical solution of three fields coupling of shallow tunnel with multi-freezing pipes is obtained. By means of the finite element program for the freezing process in dynamic static, the numerical simulation is made, and the results agree well with the site survey results.更多还原