【作者】 孙红燕；

【导师】 郑传超；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2013， 博士

【摘要】 沥青路面温缩裂缝是低温气候区存在较普遍的路面病害形式之一，一般发生在极端低温条件下，裂缝大都与道路纵向垂直且纵向间距呈现一定的规律性。目前关于沥青路面低温抗裂性的研究主要着眼于材料性能研究，路面结构的影响及裂缝间距机理方面涉及较少。本文结合甘肃地区典型路面结构及实测温度数据主要分析了沥青路面的温度应力应变响应及其与温缩理论起裂间距的关系，对日后低温地区沥青路面的材料和结构选择及设计有一定意义。对甘肃省依托工程的实测温度数据进行了规律分析和总结，发现四季气温日变化规律类似，路表温度变化规律与气温变化基本相同，大致符合正弦曲线的变化规律，但路表达到最高温的时刻略迟于气温达到最大值的时刻。温差最大值出现在路表。随着深度增加，不同时刻路面结构内的温度在同一深度处的温度差值逐渐缩小，直到一定深度处的土基中温度趋于一稳定值。依据热传导理论推导了垂直边坡均质体和斜边坡均质体在第一类边界条件下的温度场分布解析解，并与数值解进行了对比。讨论了温度场计算的一维模型、二维垂直边坡模型和二维斜边坡模型的差异性，发现二维模型边坡温度的影响范围均在距离路基边缘约1.5m的范围之内，道路中线附近路面结构温度分布仅与深度有关。从温度应力的吴赣昌解出发建立温缩开裂模型，推导沥青面层温缩开裂模型的温度应力解析表达式并进行参数分析，建立了温度应力与面层计算长度的关系。发现面层厚度增加和较好的层间粘结状态对低温抗裂性能的提高效果较好，提出在面层材料选择时应选择低模量和较小温缩系数的沥青混合料，从而减少沥青路面低温开裂现象发生。借助有限单元分析法建立沥青路面温缩裂缝的有限单元模型，考察了路表最大温度应力和路表最大温度应变与路面计算长度的关系。通过参数分析得到路基厚度取4m就可以满足温度荷载作用的计算精度要求。发现参考温度取值对路面温度应力应变影响显著，而不同的控制指标（温度应力/温度应变）对面层模量有截然不同的要求。基于线性粘弹性理论分析了降温过程中路面内的应力累积与松弛情况并进行参数分析，认为气温变化剧烈的季节更替时期是沥青路面低温开裂的高发时期，提出温度荷载重复作用会导致沥青路面出现疲劳现象产生温度疲劳裂缝。最后综合本文关于温度场、温度应力和理论起裂间距的分析结果，改进了现有沥青路面设计方法，引进了路表温度应力或温度应变的验算指标。更多还原

【Abstract】 Thermal cracking is one of the common failure modes of asphalt pavement in coldregions, which generally occurs under the extreme low temperature condition. Most cracksare perpendicular to the longitudinal direction of the road with certain spacing. At present,researches of thermal cracking mainly focus on material properties, but few involve theeffects of pavement structure and the mechanism of uniform crack spacing. In this study,thermal stress/strain response of asphalt pavement and theoretical crack spacing wereanalyzed based on typical pavement structure and the measured temperature data in Gansuprovince, which will greatly help the selection and design of pavement material and structure.Based on the temperature data from field sections in Gansu Province, it was founded therelationship between daily temperature fluctuation and time was similar throughout the yearand pavement surface temperature fluctuation follows a sinusoidal mode. The highesttemperature on pavement surface occurred slightly after that of the air temperature. Themaximum daily temperature difference was on pavement surface. The daily temperaturefluctuation decreases as the pavement depth increases, and the pavement temperature remainsconstant beyond certain depth.Based on the theory of heat conduction，the analytical solution of temperature field wasderived for homogeneous model with vertical side slope and inclined side slope under the firstboundary condition, which was later compared with the numerical solution. The differencesamong one-dimensional model and two-dimensional model with vertical side slope andinclined side slope were analyzed. For the two-dimensional model, the effects of slopetemperature boundary conditions on the temperature distribution was within1.5m to subgradeedge, whereas the temperature distribution near the road centerline depended on the depthonly.From the thermal stress solution of Wu Ganchang, the analytical solution was derived tostudy the effects of wearing course calculated length on thermal stresses within the pavement.It was found that thick surface layer and good pavement layer bonding conditions canimprove pavement thermal cracking resistance. It was also found that asphalt pavement wasmore resistant to thermal cracking with low resilient modulus and small temperature shrinkage coefficient for surface layer.Finite element model was created to study the effects of pavement calculated length onmaximum thermal stresses and strains on pavement surface. Through parameter sensitivityanalysis, it was found that pavement model with4meters thick subgrade can meet accuracyrequirement. It was also found that the reference temperature has a critical effect on thedistribution of pavement thermal stresses and strains, and different control indexes (thermalstress and thermal strain) had entirely different requirements of layer modulus.According to linear visco-elastic theory, stress accumulation and relaxation calculationand parameter sensitivity analysis during the cooling process were performed. Thermal crackswere more prominent during severe temperature fluctuation period between seasons. Arepeated thermal loading will also lead to fatigue thermal cracking. Based on the results ofthis study, the existing asphalt pavement design method was improved with the introductionof pavement surface thermal stress/strain checking index.更多还原