基于ANSYS有限元分析的沥青路面车辙研究

发布时间：2018-10-26 15:56

【摘要】：沥青混合料在高温重载条件下,粘弹塑性表现得非常明显,研究沥青路面的永久变形很重要,可以对沥青路面结构设计和车辙预防措施上提供相应的支撑与依据。利用有效的有限元模型研究沥青路面车辙,可以分析车辙过程中层间各种应力、应变变化关系以及不同作用因素下沥青路面层的力学性能,为实际路面状况提供力学参考依据。论文首先在沥青混合料室内马歇尔试验、车辙试验和蠕变试验基础上,应用ANSYS中弹塑性、粘弹性、粘弹塑性模型模拟对比验证沥青混合料的车辙规律,发现Creep模型可以有效模拟沥青混合料的车辙特征;其次与文献数据对比分析表明,Creep模型在表征全厚式沥青路面车辙上也具有效性;最后研究不同因素影响下两种不同沥青路面车辙特征以及层内力学性能。具体研究内容如下:1.应用通用有限元软件ANSYS中Creep模型,近似表征沥青路面车辙的时间硬化特点,在轮胎接地压力呈矩形分布的条件下,采用以静代动的方法,将实际动荷载等效换算成静态荷载,按照试验规程所规定的荷载作用次数,模拟室内沥青混合料的车辙形成过程,结果表明:荷载作用初期,模拟结果与室内试验车辙结果相差很大,车辙形成主要来源于混合料的压密;但随着荷载作用次数的不断增加,这种差异逐渐减小,且两种变形规律具有一致性。2.对全厚式沥青路面同样采用Creep模型,对比验证表明:Creep模型所表征的全厚式沥青路面车辙变形规律与文献中给出的规律具有一致性,模拟结果小于文献的试验结果,说明Creep模型可以近似研究全厚式沥青路面在高温与重载条件下的永久变形特性。在全厚式沥青路面应力应变云图中可以发现竖向变形主要分布在面层中层区域,最大应力出现在轮载作用轮隙中心处。3.通过模拟分析基质沥青路面和改性沥青路面在不同温度、不同荷载以及不同荷载作用次数情况下,两种沥青路面所表现的最大竖向变形、路表弯沉、轮载两侧隆起以及路面层内四种应力指标变化规律:沥青路面竖向位移随着温度、荷载作用次数以及荷载级的增加而增大,改性沥青路面的抵抗竖向变形能力要优于基质沥青路面;路表弯沉分布表明在轮载作用中心深度范围内的路表弯沉最大,逐渐向两侧减小;轮载作用两侧的隆起随着荷载作用次数的增加而增大,同时荷载级的增大也会使得隆起增大,而且最大隆起处与轮隙中心水平距离也逐渐增大;高温条件下,两种沥青路面在重复荷载作用以及荷载级不同条件下的四个应力指标规律变化一致,同时也表现出明显的数值差别,改性沥青路面比基质沥青路面更适应高温、重载条件影响;剪切应变随深度的增加先增加到最大峰值后逐渐减小;荷载级越大,剪切应变分度深度越大,相较基质沥青路面,改性沥青路面在受同样荷载级作用时剪切应变分布深度要小。
[Abstract]:Under the condition of high temperature and heavy load, the viscoelastic-plastic behavior of asphalt mixture is very obvious. It is very important to study the permanent deformation of asphalt pavement, which can provide the corresponding support and basis for the structural design of asphalt pavement and rutting prevention measures. By using the effective finite element model to study the rutting of asphalt pavement, we can analyze the relationship between stress and strain in the process of rutting and the mechanical properties of asphalt pavement under different action factors, and provide a mechanical reference for the actual pavement condition. Firstly, on the basis of indoor Marshall test, rutting test and creep test of asphalt mixture, the rutting law of asphalt mixture is verified by simulation and comparison of elastic-plastic and viscoelastic-plastic models in ANSYS. It is found that the Creep model can effectively simulate the rutting characteristics of asphalt mixture. Secondly, compared with the literature data, the Creep model is effective to characterize the rutting of full-thickness asphalt pavement. Finally, two different asphalt pavement rutting characteristics and in-layer mechanical properties are studied under the influence of different factors. The specific research contents are as follows: 1. The Creep model in ANSYS is used to approximate the time hardening characteristics of asphalt pavement ruts. Under the condition of rectangular distribution of tire earthing pressure, the actual dynamic load is equivalent to static load by static displacement method. The rutting process of indoor asphalt mixture is simulated according to the number of loads specified in the test rules. The results show that the result of simulation is very different from that of indoor test in the early stage of loading. Rutting mainly comes from the compaction of mixture. However, with the increasing of the number of loads, the difference decreases gradually, and the two kinds of deformation laws are consistent with each other. 2. The Creep model is also used for the full-thickness asphalt pavement. The comparison shows that the rutting deformation law of the full-thickness asphalt pavement represented by the Creep model is consistent with the law given in the literature, and the simulation results are smaller than the experimental results in the literature. It is shown that the Creep model can approximate study the permanent deformation characteristics of full-thickness asphalt pavement under high temperature and heavy load. In the full thickness asphalt pavement stress-strain cloud diagram, it can be found that the vertical deformation mainly distributes in the middle area of the surface layer, and the maximum stress occurs at the center of the wheel gap acting on the wheel load. The maximum vertical deformation and surface deflection of the two kinds of asphalt pavement under different temperatures, different loads and different loading times are simulated and analyzed. The variation rules of four stress indexes in both sides of the wheel load and the pavement layer are as follows: the vertical displacement of asphalt pavement increases with the increase of temperature, the number of loads and the load level. The resistance to vertical deformation of modified asphalt pavement is better than that of matrix asphalt pavement. The distribution of road surface deflection indicates that the deflection of the road surface is the largest in the depth range of the center of the wheel load and gradually decreases to the two sides. The uplift on both sides of the wheel load increases with the increase of the number of loads, at the same time, the increase of the load level also increases the uplift, and the horizontal distance between the maximum uplift and the center of the wheel gap increases gradually. Under the condition of high temperature, the changes of the four stress indexes of the two kinds of asphalt pavement under repeated loads and different load levels are the same, and at the same time, there are obvious numerical differences. The modified asphalt pavement is more suitable for high temperature than the base asphalt pavement. The influence of heavy load condition; The shear strain first increases to the maximum peak value and then decreases gradually with the increase of the depth; the larger the load level, the greater the shear strain indexing depth, and the smaller the shear strain distribution depth of the modified asphalt pavement is when it is subjected to the same load stage.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.217;U418.68

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