【作者】 毛雪松；

【导师】 胡长顺； 王秉纲；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2004， 博士

【摘要】 多年冻土地区路基的冻结过程是温度场、水分场及应力场相互作用的极其复杂的传热学、物理化学和力学的综合问题。路基的热状况、水分状况与变化规律及由此引起的应力重分布是引起道路冻害的主要因素。正确认识多年冻土的性质，预报路基热稳定状况，改善冻土中水、热分布，避免不均匀变形、纵向开裂等病害发生，是多年冻土道路建设和发展的需要。本文从分析国内外温度场、水分场、应力场及其耦合效应的研究现状出发，针对传统温度场、水分场及应力场等单一场研究难以深入揭示路基冻胀病害规律，定量解释各种病害发生原因的局限性，进行了系统深入的研究并取得系列的研究成果。 1．针对多年冻土地区路基与一般路基的不同，在非稳态温度场控制方程的基础上建立了多年冻土地区伴有相变的路基非稳态温度场控制方程，采用Galerkin法求解伴有相变的路基非稳态温度场偏微分方程，在空间域内采用混合单元有限元网格划分，在时间域内用有限差分格式划分的混合解法进行温度场有限元分析。 2．应用冻土路基温度场室内大型模型试验模拟野外实际路基的状况，并利用多年冻土地区伴有相变的非稳态温度场控制力程进行模拟验算，进一步论证了温度场模型的正确性及采用室内大型模型试验模拟野外现场路基的可行性。 3．针对多年冻土路基中热流及温度分布将引起土体中水分运动参数及其土水势值发生变化的现象，基于传统土体水分等温模型，引进非等温扩散流方程，考虑温度差值形成的温度梯度也会造成水分流动及相变问题，建立冻土路基中水分迁移的有限元控制方程，应用有限元的数值解析方法研究水分迁移规律。 4．通过对室内土样试件温度场和水分场的动态观测，得出温度梯度是导致水分迁移产生的重要因素之一，并应用水热耦合模型对试件的温度场、水分场进行数值模拟，论证了在冻土路基水分迁移控制方程中引进温度梯度水分扩散率概念的合理性，验证了水热耦合数值模型的正确性。 5．根据冻土路基非稳态相变温度场控制方程及水分场迁移控制方程，在考虑第一类边界条件下，对青藏公路K3363+800段冻土路基的温度场、水分场进行了计算，并与实测值进行比较，进一步证明了水热耦合模型的正确性。 6．基于弹性理论建立了冻土路基变形场及应力场的二维数值计算模型，并应用有限元法求解路基土体冻结时变形场和应力场分布规律。通过对土基范围内冻胀带对路基土体的应力场和变形场的研究，进一步分析了冻土路基破坏的机理。在此基础上，分析了不同范围冻胀带对路基顶面变形场和应力场的影响，提出敏感冻胀带的范围及应力极值点产生的位置。 7．通过建立不同的融沉计算模型，进行冻土路基变形场及应力场二维数值计算，分析了路基表面的竖向及横向位移分布的规律、路中沿深度方向的竖向位移变化规律及路基表面横向应力分布规律。 8.应用冻土路基非稳态温度场的控制方程和冻土路基变形场的二维数值计算模型，对1月及12月路基温度场、应力场和变形场进行有限元计算，分析了温度场的动态变化对变形场分布规律的影响，及路基发生不均匀变形的原因。 9.借助冻土路基中水分迁移的有限元控制方程和冻土路基变形场及应力场的二维数值计算模型，对不同水分迁移造成的土体冻胀路基变形场和应力场进行了研究。 10.基于多年冻土地区路基非稳态温度场控制方程、水分迁移的有限元控制方程及路基变形场和应力场的计算模型，提出了水热力三场祸合计算模型及三场祸合计算的流程。并结合实体工程，进一步说明水热力三场的藕合过程，分析了1月10日.路基温度场、水分场及应力场相互作用影响的规律。更多还原

【Abstract】 The freezing course of the permafrost sub-grade synthesizes heat exchanging, physical chemistry and mechanics, which is concerned with the complicated interacting process of the temperature field, moisture field and stress field. Both the condition of the heat, the moisture of the subgrade, their changing law and the stress distributing are the key factors to cause the frost damages. Accurately understanding the characteristics of the permafrost, forecasting the heat stabilization status, punishing the frost damage by disposing and improving the moisture, heat condition of the frost, and preventing the damage of the Non-uniform deformation and longitudinal crack guarantee the constructing and developing of the permafrost engineering. First the dissertation generally analyses the developing history of the temperature field, moisture field, stress field and their coupling. Based on the shortcoming that the study on only one of the temperature field, moisture field, stress field is difficult to reveal thoroughly the law of the freezing damage of the subgrade, and to explain rationally the deep reason of all the damages, the research are as follows:1. Aiming at the difference between the permafrost subgrade and the common subgrade, this dissertation formulates the control equation of the non-steady temperature field with phase changing of the permafrost based on the traditional equation. Then the dissertation solves the partial differential equation of the control equation by Galerkin method, analyses the equation with the finite element method by adopting the grid segmentation of the mixture cell in space domain and format segmentation in time domain by the mixture solution of the finite difference.2. This dissertation puts forward an innovation, which is to adopt the large-scale inside test of the temperature field of the permafrost subgrade to simulate the field real environment. At the same time the innovation is validated by the control equation of the non-steady temperature field with phase changing of the permafrost, further the accuracy of the model of the temperature field and the feasibility of the innovation are verified.3. Thinking about the phenomenon that the heat stream and temperature distribution of the permafrost subgrade arise the change of the moving parameter of the moisture in soil, this dissertation introduces the non-isotherm model of the spread flow equation on the basis of the traditional isotherm model of the moisture in soil. Considering that the temperature grads that are consisted of temperature differenceconduces the flow and phase change of the moisture, this dissertation gives out the finite element control equation of the moisture transfer in the permafrost subgrade. At the same time, the dissertation does some research on the law of moisture transfer by the finite element numerical resolution.4. Through the dynamic observation on both the temperature field and the moisture field of the inside soil specimen, this dissertation concludes that the temperature grads is crucial to induce the moisture transfer. Applying the coupling model of the moisture and heat field, the dissertation numerically simulates the temperature field and moisture field of the soil specimen. The simulation validates therationality of the moisture difrusivity concept DT, which is introduced in the controlequation of the moisture transfer in permafrost subgrade. Further the dissertation demonstrates the accuracy of the numerical coupling model of the moisture and heat field.5. According to both the non-stationary phase change temperature field control equation and the moisture transfer control equation in the permafrost subgrade underthe first bound limitation, this dissertation calculates the temperature and moisture field of the section of Qinghai-Tibet highway k3363+800. The compare of the real test values and the calculation proves the preciseness of the coupling model of the heat and moisture field.6. Based on the elasticity theory, the dissertation更多还原