基于随机荷载谱的沥青混合料疲劳性能研究

发布时间：2018-05-17 05:27

本文选题：沥青混合料 + 疲劳寿命　；参考：《扬州大学》2015年硕士论文

【摘要】：沥青路面使用期间,受到车辆荷载的反复作用,结构内部应力或应变长期处于交迭变化状态,致使沥青混合料强度不断衰减。当荷载重复作用超过一定次数后,路面内所产生的应力超过其结构强度降低以后的抗力,导致路面结构发生疲劳破坏。路面上作用的车辆荷载是一种随机荷载,因此,车辆荷载在路面结构层内所产生的应力/应变也具有随机性。目前,国内外研究者大多采用常幅荷载(应力/应变)下的疲劳试验。这并不能完全实现对沥青路面在实际荷载作用下疲劳性能的模拟。因此,本文采用四点小梁弯曲疲劳试验方法,研究随机变幅应变下的沥青混合料疲劳特性。首先,本文选用合理的路面荷载图式和力学模型计算重载作用下路面结构应变响应。运用壳牌路面设计软件BISAR3.0,分别计算倒装结构沥青路面和半刚性基层沥青路面的面层内应变。在道路深度方向和道路横断面方向,对比不同荷载条件下的应变响应,确定沥青面层结构层内应变最不利位置点。对现有文献中提供的轴载谱进行简化分析后,通过结构计算将其转换为倒装面层结构中最不利位置的应变谱。经统计分析,得出该点处应变谱符合高斯分布。其次,采用澳大利亚生产的UTS015疲劳试验机对改性沥青SMA13混合料进行四点弯曲疲劳试验,得到了5种常幅应变水平下的疲劳寿命,建立了疲劳寿命方程。编制了3种符合高斯分布的随机变幅疲劳应变谱,实现了沥青混合料在随机变幅应变下的弯曲疲劳试验,确定了三种应变谱作用下的疲劳寿命。最后,通过对现有寿命预估模型的分析比较,建立了随机变幅应变作用下沥青混合料的疲劳寿命预测模型。与常规的Miner定理预估模型相比,发现基于连续疲劳损伤理论的预估寿命能够更好的预测随机应变谱下的沥青混合料疲劳寿命,且模型预测结果与随机变幅应变疲劳试验结果误差不大。该模型可运用常幅应疲劳变试验获得的疲劳方程,以及实际路面的荷载谱预测沥青混合料疲劳寿命,具有较好的适用性。
[Abstract]:During the use of asphalt pavement, the internal stress or strain of the structure is in the state of overlap and change for a long time under the repeated action of the vehicle load, which causes the strength of the asphalt mixture to decline continuously. When the repeated loads exceed a certain number of times, the stress generated in the pavement exceeds the resistance of the structure after its strength is reduced, which leads to the fatigue failure of the pavement structure. The vehicle load acting on the pavement is a kind of random load, so the stress / strain produced by the vehicle load in the pavement structure layer is also random. At present, most researchers at home and abroad adopt fatigue tests under constant amplitude load (stress / strain). This can not fully simulate the fatigue performance of asphalt pavement under actual load. In this paper, the fatigue characteristics of asphalt mixture under random variable amplitude strain are studied by using four point trabecular bending fatigue test method. Firstly, a reasonable load schema and mechanical model are used to calculate the strain response of pavement structure under heavy load. Using Shell pavement design software BISAR3.0, the internal strain of asphalt pavement with inverted structure and semi-rigid base is calculated respectively. In the depth direction of the road and the cross-section direction of the road, the strain response under different load conditions is compared to determine the most unfavorable position of the strain in the asphalt pavement structure layer. After the simplified analysis of the axial load spectrum provided in the existing literature, the strain spectrum of the most unfavorable position in the inverted surface structure is converted into the strain spectrum by structural calculation. Through statistical analysis, it is concluded that the strain spectrum at this point accords with the Gao Si distribution. Secondly, the four-point bending fatigue test of modified asphalt SMA13 mixture was carried out by using the UTS015 fatigue testing machine made in Australia. The fatigue life of five kinds of constant amplitude strain levels was obtained, and the fatigue life equation was established. Three kinds of random variable amplitude fatigue strain spectrum according to Gao Si distribution are compiled. The bending fatigue test of asphalt mixture under random variable amplitude strain is realized, and the fatigue life of asphalt mixture under three kinds of strain spectrum is determined. Finally, through the analysis and comparison of the existing life prediction models, the fatigue life prediction model of asphalt mixture under random variable amplitude strain is established. Compared with the conventional Miner theorem prediction model, it is found that the prediction life of asphalt mixture based on continuous fatigue damage theory can better predict the fatigue life of asphalt mixture under random strain spectrum. And the model prediction results have little error with random variable amplitude strain fatigue test results. This model can be used to predict the fatigue life of asphalt mixture by the fatigue equation obtained from the constant amplitude fatigue test and the load spectrum of the actual pavement. It is suitable for predicting the fatigue life of asphalt mixture.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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