基于计算流体力学沥青路面水损害的细观分析

发布时间：2018-12-12 18:22

【摘要】：随着我国高等级公路的建设和发展，半刚性基层沥青路面得到了广泛的应用。但是由于自然因素以及车辆荷载等因素，许多高速公路在通车数年之后，沥青面层就产生了大量麻面、松散、唧浆、坑洞、网裂等破坏现象，而多种破坏现象都与水有着直接或间接的关系。为此，我国道路工作者围绕水损害问题进行了大量的研究。很多人致力于水损坏的破坏机理，破坏程度，防护修补措施以及新型材料的研究，为了分析计算动水压力的大小以及时程变化情况，一部分研究人员致力于应用有限元计算方法模拟沥青路面结构，来分析沥青路面早期水损害的破坏机理。但是，很少有人从细观的角度分析沥青路面孔隙内部的压强分布以及动水作用下沥青混合料结构内部的应力分布情况。本文在前人研究的基础上结合计算流体力学，假设了沥青路面孔隙模型，对沥青路面孔隙内部流体的压强分布，流速分布，流场分布情况进行了分析，对孔隙周边的沥青混合料的应力分布进行了计算分析。并结合试验测得的沥青自身的粘结力和沥青与骨料之间的粘附力，判断沥青混合料早期水损害的形式与位置。第一，通过观察沥青路面孔隙分布情况，结合试件内部孔隙的形状，大小，连接孔隙的缝隙数量等因素，分析了沥青路面中孔隙可能存在的形式。并结合流体力学基本理论，通过对不同形状模型进行试算，建立了沥青路面孔隙的标准模型。第二，基于流体力学基本理论以及湍流理论，选取计算湍流的标准k计算模型，对沥青路面孔隙标准模型进行了计算分析。得到了沥青路面孔隙内液体压强的分布情况；探讨了沥青混合料有可能最先发生损伤的位置；对比了在连接孔隙的缝隙数量，尺寸以及连通性不同的情况下液体压强分布情况；对出口缝隙存在变径的情况进行了分析。对封闭缝隙存在于不同位置的六种情况进行了计算分析，研究了封闭缝隙位置对孔隙内部的压强分布造成的影响。第三，建立了流固耦合模型，应用单向耦合，，计算了在随时间变化的载荷作用下沥青混合料的应力分布情况，通过对应力的大小和方向的分析，推断沥青混合料可能出现的破坏位置以及破坏的先后顺序。最后，利用前人的试验方法，测定了沥青的粘附力沥青与骨料之间的粘结力的大小。对比沥青混合料的受力情况，分析沥青混合料早期水损害的破坏形式。
[Abstract]:With the construction and development of high-grade highway in China, semi-rigid base asphalt pavement has been widely used. However, due to natural factors and vehicle loads, after many highways were opened to traffic for several years, the asphalt surface produced a large number of damage phenomena, such as hemp surface, loose, jelly, pothole, net crack and so on. Many damage phenomena are directly or indirectly related to water. Therefore, the road workers in our country have carried out a great deal of research on the problem of water damage. Many people devote themselves to the study of the damage mechanism, damage degree, protective measures and new materials of water damage, in order to analyze and calculate the size of dynamic water pressure in order to change in time. Some researchers apply finite element method to simulate asphalt pavement structure to analyze the failure mechanism of water damage in the early stage of asphalt pavement. However, few people analyze the pressure distribution in the pore of asphalt pavement and the stress distribution of asphalt mixture structure under the action of dynamic water. In this paper, the pore model of asphalt pavement is assumed on the basis of previous studies, and the pressure distribution, velocity distribution and flow field distribution of the pore fluid in asphalt pavement are analyzed. The stress distribution of asphalt mixture around pore is calculated and analyzed. Combined with the adhesive force of asphalt itself and the adhesion force between asphalt and aggregate, the form and position of water damage in the early stage of asphalt mixture were judged. Firstly, by observing the pore distribution of asphalt pavement and combining the shape and size of the internal pores and the number of cracks connected with the pores, the possible forms of the pores in the asphalt pavement are analyzed. Combined with the basic theory of fluid mechanics, the standard model of asphalt pavement porosity is established by the trial calculation of different shape models. Secondly, based on the basic theory of fluid mechanics and turbulence theory, the standard k model for calculating turbulence is selected, and the pore standard model of asphalt pavement is calculated and analyzed. The distribution of liquid pressure in the pore of asphalt pavement is obtained, the position where the asphalt mixture may first damage is discussed, and the distribution of liquid pressure is compared under the different number, size and connectivity of the connecting pore. The influence of diameter variation on the exit gap is analyzed. In this paper, the influence of the closed slot position on the pressure distribution in the pore is studied by calculating and analyzing the six conditions in which the closed slot exists in different positions. Thirdly, the fluid-solid coupling model is established and the stress distribution of asphalt mixture under time-varying loads is calculated by unidirectional coupling. The magnitude and direction of the stress are analyzed. The possible failure location and the sequence of failure of asphalt mixture are inferred. Finally, the adhesive force between asphalt and aggregate was measured by the previous test method. Comparing the stress of asphalt mixture, the failure form of water damage in early stage of asphalt mixture is analyzed.
【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】：U416.217;U418.6

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