冻土是一种对温度敏感和易变的特殊工程土类，它是在地壳内热源和外热源的综合作用下形成、发展、退化及消亡。青藏公路由北至南穿越550km分布着多年冻土的地区，由于恶劣的气候条件及冻土特殊的工程性质导致青藏公路病害情况十分严重。研究水热作用对冻土路基变形稳定性的影响，将对多年冻土地区路基的设计、施工和稳定性研究具有重要的意义。 本文以青藏公路多年冻土区五道梁段为工程背景，在理论上对多年冻土地区路基温度场、水分场和变形场进行研究，分析影响路基热稳定性的因素及相应关系、水分迁移原理及应力与变形场的相关概念，探讨了冻土路基中温度、水分及应力之间的相互作用原理，并采用有限元软件对冻土路基温度场、渗流及变形场进行模拟，研究考虑大气辐射的阴阳坡效应、风速风向、降水蒸发情况下温度场的分布规律；建立大气降水入渗模型对路基渗流作用的水分分布展开研究，并分析路基在冻结与融化时期水分场的变化规律；在温度场与水分场计算结果基础上通过耦合的方法研究路基的变形规律，从而揭示路基病害的发生机理。 研究结果表明，冻土路基温度场的季节活动深度为2~8m，路基深部土体的温度受外界温度的影响呈现滞后性；冻结与融化时期在路中以下2~4m深度范围内温度梯度较大；在路基融化时期的大气降水渗流过程中，路肩以下路基填土范围内的饱和度与地基的饱和度出现较大的差异，呈现出明显的分层现象；冻结时期土中未冻水向冻结锋面迁移导致路中以下2~3m深处含水率突增，同时温度差异导致路中与路肩以下水分发生横向迁移；冻结与融化时期路基总变形量较大，同时边坡与坡脚处发生横向变形。水热作用下路基产生的不均匀的冻胀与融沉变形是造成青藏公路道路病害的根本原因。

Frozen soil is a kind of temperature sensitive and special engineering soil type, it is within the earth's crust outside heat source and heat source to a combination of formation, development, degradation, and death. The Qinghai-Tibet highway 550 kilometers from north to south through the distribution of permafrost region, due to bad weather conditions and special engineering properties of permafrost caused the Qinghai-Tibet highway diseases situation is very serious. Research water thermal stability of permafrost subgrade deformation, the influence of the roadbed in permafrost region is of great significance to the design, construction and stability study. Based on the engineering background of Qinghai-Tibet highway Wu Dao Liang section, roadbed in permafrost region in theory to study the temperature field, moisture field and strain field, analysis of factors influencing the thermal stability of subgrade and the corresponding relationship, moisture migration principle and related concepts of stress and strain field, temperature, moisture and stress in the frozen soil subgrade are discussed the interaction between principle, and uses the finite element software of permafrost subgrade, to simulate the temperature field, seepage and deformation field is considered slope and effect of atmospheric radiation, wind speed and direction, rainfall evaporation conditions of temperature field distribution; Atmospheric precipitation infiltration model is established to study the roles of subgrade seepage water distribution, analysis of subgrade in freezing and thawing period change rules of moisture field; Based on the temperature field and moisture field calculation results through coupling method to study the deformation law of the subgrade, so as to reveal the mechanism of roadbed disease. The results show that the depth of permafrost embankment temperature field season activity 2 ~ 8 m, the temperature of the deep soil roadbed under the influence of ambient temperature lag, the freezing and thawing period respectively in the 2 m to 4 m depth within the scope of temperature gradient is bigger; In the process of atmospheric precipitation seepage, within the scope of the shoulder the subgrade soil saturation and the foundation of saturation appear bigger difference, presents the obvious stratification phenomenon; Water potential and the phase change temperature potential influence to the freeze front spurt migration lead to moisture content, temperature difference, which results in the road and at the same time shoulder the following water lateral migration; Freezing and thawing period around 70 mm total deformation of subgrade, the lateral deformation of slope and slope toe occur at the same time. Hydrothermal non-uniform roadbed happened under the action of frost heave and thawing settlement deformation is the root cause of the Qinghai-Tibet highway road diseases.