沥青混凝土疲劳扩展温度影响特性研究

发布时间：2018-01-10 12:12

本文关键词：沥青混凝土疲劳扩展温度影响特性研究　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：众所周知,几十年来我国的高速公路建设发展迅速。高速公路的总里程已达到世界第二的水平,我们道路工作者面临的问题是对于已经使用道路的病害和工作机理的认识是否深入,这将对我们接下来的公路建设有着比较重大的影响。对沥青混凝土的疲劳问题主要的研究主要分为四大类。主要包括：现象学法、断裂力学法、耗散能法和起源于金属学科的近似损伤力学法。总体来说研究时对温度考虑不够全面,所以论文研究集中在沥青混凝土疲劳扩展的温度影响特性研究。论文主要通过ABAQUS软件来模拟现实生活中高等级沥青混凝土道路的工作状况,将疲劳问题放在一个整体的工作环境下考虑,尽可能的去贴近实际道路的使用情况,采用仿真的实际行车荷载,模拟材料的整体受力情况。首先对于沥青混凝土疲劳的问题,论文选定了损伤力学法来进行研究,依据非线性疲劳模型的原理,通过对ABAQUS的UMAT的子程序的研究和编制。最终对材料的本构模型作出改进,引入损伤参量D及其累积准则,根据研究设定损伤累积到0.5时裂缝出现。对于整个道路的温度场的设定,考虑了太阳辐射、风速、热对流等一系列的大气条件,对于道路模型则认真考虑了各个材料的热传导、热容等物理性质,并设定了相应的边界条件,成功模拟出了符合要求的温度场,并将温度场代入即将使用的疲劳模型中。对于材料的温度特性研究,论文采用了两种不同的模型来研究材料模量与温度的关系,由于沥青混凝土材料的多相性,所以在高温和低温时相应的变化趋势是不同的,在低温时采用线性变化,高于20摄氏度时则采用指数型变化,并以此编制材料的子程序。道路模型的建立,论文采用的是平面应变模型,采用的模型尺寸较大,所以四周的边界条件为全部约束,符合实际的应力状况。各个层位的厚度和材料参数的选取都依照规范,按照同一交通量来计算得出,一共设定了三种不同的道路模型,最后将所建立的所有的模型进行耦合计算,得出在温度影响下的疲劳扩展规律,验证了研究手段的可行性,也对高海拔季冻地区的高速公路建设提供了一定程度的指导建议。
[Abstract]:As we all know, the highway construction in China has developed rapidly in recent decades. The total mileage of expressway has reached the second level in the world. The problem we road workers face is whether we have a deep understanding of the diseases and working mechanisms of roads that have already been used. This will have a significant impact on our next highway construction. The main research on the fatigue of asphalt concrete is divided into four categories, including: phenomenological method, fracture mechanics method. The dissipative energy method and the approximate damage mechanics method originated from the metal discipline. In general, the temperature is not fully considered in the study. So this paper focuses on the temperature effect of asphalt concrete fatigue propagation. This paper mainly through the ABAQUS software to simulate the real life of high-grade asphalt concrete road work. The fatigue problem is considered in a whole working environment, as far as possible to close to the actual use of the road, using the actual traffic load simulation. First of all, for the problem of asphalt concrete fatigue, the damage mechanics method is selected to study, according to the principle of nonlinear fatigue model. Finally, the damage parameter D and its accumulation criterion are introduced by improving the constitutive model of ABAQUS by studying and compiling the subroutine of UMAT of ABAQUS. According to the study, the damage accumulates to 0.5 when cracks appear. For the whole road temperature field, a series of atmospheric conditions, such as solar radiation, wind speed, thermal convection and so on, are considered. For the road model, the physical properties of each material, such as heat conduction and heat capacity, are carefully considered, and the corresponding boundary conditions are set, and the temperature field that meets the requirements is successfully simulated. And the temperature field will be replaced in the fatigue model. For the temperature characteristics of materials, two different models are adopted to study the relationship between material modulus and temperature, due to the heterogeneous nature of asphalt concrete materials. So the trend of change in high temperature and low temperature is different, the linear change is adopted at low temperature, and the exponential change is used when the temperature is higher than 20 degrees Celsius, and the subroutine of material and the establishment of road model are worked out. In this paper, the plane strain model is adopted, and the size of the model is large, so the boundary conditions around it are all constrained, in line with the actual stress conditions. The thickness of each layer and the selection of material parameters are in accordance with the specifications. According to the same traffic volume calculation, a total of three different road models are set up. Finally, all the models are coupled to obtain the fatigue growth law under the influence of temperature. The feasibility of the research method is verified, and some guidance suggestions are provided for highway construction in high altitude seasonal frozen area.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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