沥青混凝土路面温度应力及温缩裂缝研究

发布时间：2018-06-02 09:55

本文选题：沥青路面 + 温度场　；参考：《吉林大学》2014年硕士论文

【摘要】：我国北方寒冷地区沥青混凝土路面的低温开裂现象十分普遍，经过一个寒冷的冬季后，经常在路表面出现按一定间距分布的横向裂缝，这种现象在世界其他寒冷地区也经常发生。裂缝的出现为水进入道路结构内提供了有利条件，从而导致道路结构的承载能力及服务寿命显著降低，因此对寒冷地区沥青混凝土路面进行温度应力分析具有非常重要的现实意义。论文首先根据工程路段实测温度值，应用有限元软件ANSYS模拟道路结构沿深度方向的温度场分布，同时计算结构层温度梯度。研究结果表明：道路表面与土基底面的温差越大，结构内的温度梯度越大；随着道路深度的增加，温度梯度的绝对值越来越小；在夏季和秋季，结构层温度梯度为正温度梯度，而在冬季，结构层温度梯度为负温度梯度。然后，在参考大量国内外相关文献及研究成果的基础上，建立低温下沥青混凝土道路热—结构耦合三维有限元模型，分析降温幅度、沥青混凝土面层及基层参数对沥青路面温度应力的影响规律，此外还考虑了沥青面层与基层间的接触状况对结构温度应力的影响。计算结果表明：沥青路面的最大温度应力出现在路表面，若最大温度应力超过沥青混合料本身的极限抗拉强度，将在路表面出现温缩裂缝；降温幅度越大，结构内产生的温度应力也越大；面层厚度的增加可以减小温度应力，但是影响效果并不明显；沥青面层劲度模量的变化对路表面、上面层层底与下面层层底温度应力的影响比较明显，随着模量的增加，温度应力也随着增大，而对基层层底与底基层层底温度应力的影响并不大；当沥青面层温缩系数增加时，路表面、上面层层底与下面层层底的温度应力都随着增大，最大温度应力基本都增加了原来的一半，而基层层底与底基层层底的温度应力变化不大；基层厚度及模量的变化对结构温度应力的影响非常小；利用接触单元模拟层间非连续接触状态，当下面层与基层之间接触状态不同时，在接触状态不同处温度应力的变化非常明显，由于接触模型受力响应更符合道路的实际工作状态，所以在进行沥青路面结构设计时建议采用接触模型进行分析。最后，在考虑沥青路面温缩裂缝不同影响因素的基础上，，根据不同影响因素对路面温度应力的分析，提出预测沥青混凝土路面温缩裂缝间距的方法。通过有限元分析计算可知，道路所处环境降温幅度越大，沥青路面的裂缝间距越小；沥青面层及基层厚度的增加可以减小裂缝间距，但是贡献不大；随沥青面层模量的增加，裂缝间距缩短；随沥青面层温缩系数的增加，裂缝间距逐渐缩短；基层模量变化时，裂缝间距不变。因此可以看出，沥青路面的开裂与否不仅与材料本身的性质有关，而且还与道路结构情况相关。
[Abstract]:The phenomenon of asphalt concrete pavement cracking at low temperature is very common in the cold area of northern China. After a cold winter, the transverse cracks often appear on the road surface according to the distance between them. This phenomenon also occurs frequently in other cold regions of the world. The occurrence of cracks provides favorable conditions for water to enter the road structure, thus leading to a significant decrease in the bearing capacity and service life of the road structure. So it is very important to analyze the temperature stress of asphalt concrete pavement in cold area. Firstly, according to the measured temperature value of engineering section, the temperature field distribution of road structure along the depth direction is simulated by finite element software ANSYS, and the temperature gradient of structure layer is calculated at the same time. The results show that the greater the temperature difference between the road surface and the bottom of the soil foundation, the greater the temperature gradient in the structure, the smaller the absolute value of the temperature gradient with the increase of road depth, and the more positive the temperature gradient of the structure layer is in summer and autumn. In winter, the temperature gradient of the structure layer is negative. Then, on the basis of reference to a large number of domestic and foreign literatures and research results, a three-dimensional finite element model of thermal-structure coupling for asphalt concrete road at low temperature is established, and the temperature reduction range is analyzed. The influence of asphalt concrete surface and base course parameters on the temperature stress of asphalt pavement is also considered. In addition, the influence of the contact between asphalt surface and base on the structure temperature stress is also considered. The results show that the maximum temperature stress of the asphalt pavement appears on the road surface. If the maximum temperature stress exceeds the ultimate tensile strength of the asphalt mixture itself, there will be temperature shrinkage cracks on the road surface. The larger the temperature stress is in the structure, the more the thickness of the surface layer can reduce the temperature stress, but the effect is not obvious. The influence of the temperature stress on the top bottom and the bottom layer is obvious. With the increase of the modulus, the temperature stress also increases, but the effect on the temperature stress of the base layer and the bottom layer is not great; when the temperature shrinkage coefficient of the asphalt surface increases, On the road surface, the temperature stress of the top layer bottom and the bottom layer increases with the increase, and the maximum temperature stress basically increases by half of the original, but the temperature stress of the base layer and the bottom of the bottom layer do not change much. The influence of the thickness and modulus of the base layer on the temperature stress of the structure is very small, the contact element is used to simulate the discontinuous contact state between the layers, and the contact state between the current surface layer and the base layer is different. The change of temperature stress in different contact state is very obvious. Because the stress response of the contact model is more in line with the actual working state of the road, it is suggested that the contact model should be used in the design of asphalt pavement structure. Finally, on the basis of considering the different factors affecting the temperature shrinkage crack of asphalt pavement, according to the analysis of different influencing factors to the temperature stress of the pavement, the method of predicting the space between the temperature shrinkage cracks of asphalt concrete pavement is put forward. The results of finite element analysis show that the larger the cooling range of the road is, the smaller the crack spacing of asphalt pavement is, the smaller the crack spacing is with the increase of the thickness of asphalt surface and the base course, but the less contribution is made; with the increase of asphalt surface modulus, The crack spacing is shortened with the increase of temperature shrinkage coefficient of asphalt surface, and the crack spacing is not changed when the base modulus changes. Therefore, it can be seen that the cracking of asphalt pavement is not only related to the properties of the material itself, but also related to the road structure.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.21

【参考文献】