沥青混合料断裂参数A和n的取值研究

发布时间：2018-05-20 01:26

本文选题：反射裂缝 + Overlay　；参考：《武汉工程大学》2015年硕士论文

【摘要】：沥青路面因其行车舒适已成为道路铺面工程的主要类型。无论是旧水泥混凝土路面加铺沥青面层,还是新建半刚性基层沥青路面,或是对旧沥青路面加罩处理,反射裂缝都是沥青路面常见病害之一。反射裂缝的存在,给雨水进入路面提供路径,雨水会顺着基层裂缝进一步往下渗以致软化土基,或滞于加铺层与下卧层之间,在行车荷载作用下产生极大动水压力而冲刷基层和沥青混合料,削减路面强度而导致沥青路面大面积损坏。但对一条道路而言,出现反射裂缝并不意味着道路完全破坏。只要反射裂缝不扩展到路面顶部,雨水不进入道路内部,损坏就不会加剧。要研究反射裂缝的扩展特性,就需要了解断裂力学里关于裂纹扩展速率的研究。即著名的Paris公式,现今工程应用中裂纹扩展预估模型的基础,其形式为:其中N-荷载作用次数;c-裂缝长度;ΔK-应力强度因子变化值;A、n-材料的断裂参数。本课题在目前已有的研究成果上,结合Overlay Tester试验方法,针对武汉地区特有的环境因素和材料因素,试图获取裂缝扩展预估模型Paris公式中的断裂参数A和n值。为后续准确预估沥青混合料的疲劳裂纹扩展寿命(裂纹的萌生,裂纹的扩展)提供支持。本文首先简要介绍反射裂缝的产生和扩展机理及Overlay Tester试验方法;其次通过数值有限元分析软件建立裂纹扩展模型,计算分析实际沥青路面反射裂缝产生与扩展的情况;同时建立Overlay Tester计算模型,分析在特定试验条件下,应力强度因子SIF随裂缝扩展长度c的关系;然后进行Overlay Tester试验获取荷载作用次数与单圈最大荷载的关系,结合数学回归所得归一化单圈最大荷载与裂纹扩展长度的关系,求得裂纹扩展长度c和荷载作用次数N的关系;对比Paris公式特点分析计算断裂参数A和n值;最后对基于武汉地区的实际温度、材料通过试验验证求解A、n值。
[Abstract]:Asphalt pavement has become the main type of road pavement because of its driving comfort. Whether the old cement concrete pavement is overlaid with asphalt surface, the semi-rigid base asphalt pavement is built, or the old asphalt pavement is covered, the reflection crack is one of the common diseases of asphalt pavement. The presence of reflective cracks provides a path for Rain Water to enter the road, and Rain Water seeps further down the base crack to soften the soil foundation, or lag between the overlay and the underlying layer. Under the action of driving load, great hydrodynamic pressure is produced and the base course and asphalt mixture are washed away, and the strength of the pavement is reduced, which results in the extensive damage of the asphalt pavement. But for a road, the presence of reflective cracks does not mean that the road is completely destroyed. As long as the reflective cracks do not extend to the top of the road and the Rain Water does not enter the road, the damage will not worsen. In order to study the propagation characteristics of reflective cracks, it is necessary to study the crack propagation rate in fracture mechanics. This is the famous Paris formula, which is the basis of the prediction model of crack growth in current engineering applications, in which the N- loading times and the crack length, and the variation of 螖 K-stress intensity factor are the fracture parameters of the material. Based on the existing research results and the Overlay Tester test method, this paper attempts to obtain the fracture parameters A and n in the Paris formula of the fracture propagation prediction model, aiming at the special environmental and material factors in Wuhan area. It provides support for predicting the fatigue crack propagation life (crack initiation, crack propagation) of asphalt mixture. In this paper, the mechanism of reflection crack generation and propagation and the Overlay Tester test method are briefly introduced, and then the crack propagation model is established by numerical finite element analysis software, and the actual asphalt pavement reflection crack generation and propagation is calculated and analyzed. At the same time, the Overlay Tester model is established to analyze the relationship between stress intensity factor (SIF) and crack propagation length c under specific test conditions, and then the relationship between the number of loads and the maximum load of single circle is obtained by Overlay Tester test. Based on the relationship between the normalized single loop maximum load and the crack propagation length, the relationship between the crack propagation length c and the number of loads N is obtained, and the fracture parameters A an dna re calculated by comparing the characteristics of the Paris formula. Finally, based on the actual temperature in Wuhan area, the material is verified by experiments to solve the value of an.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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