基于多级等幅荷载下的沥青混合料损伤累积和沥青面层疲劳损伤破坏研究

发布时间：2018-04-16 14:08

本文选题：沥青混合料 + 四点弯曲疲劳试验　；参考：《华南理工大学》2014年博士论文

【摘要】：疲劳损伤破坏是沥青路面的主要破坏形式之一，也是沥青路面结构设计重点考虑的问题。而沥青混合料作为沥青路面主要的建筑材料，研究其在交通荷载作用下的疲劳损伤累积进程以及疲劳寿命预测是研究沥青路面疲劳损伤破坏的重要手段和需要解决的关键性问题之一。论文依托国家自然科学基金重点项目“沥青路面随机疲劳累积损伤机理研究（51038004）”，通过不同加载方式下四点弯曲小梁疲劳试验，揭示了沥青混合料各性能指标参数的变化规律，开展了基于劲度模量衰减的与加载历史及次序相关的沥青混合料非线性疲劳损伤研究，对于改善现有的沥青路面结构疲劳设计具有重要的科学参考价值。通过4种应变水平下的单级荷载加载的四点弯曲小梁疲劳试验，提出了确定初始劲度模量以及失效判据的方法，据此给出了单级荷载作用下与劲度模量和应变大小相关的沥青混合料疲劳寿命预测方程，同时分析不同应变水平下弯拉劲度模量的衰减规律，建立了与加载次数，加载大小及劲度模量相关的幂函数疲劳累积损伤模型，确定沥青混合料疲劳损伤演变呈非线性的特性。通过不同加载方式的多级等幅荷载下的疲劳试验，，获得了不同荷载大小、不同加载次数及不同加载顺序下弯拉劲度模量、耗散能变化率等疲劳损伤相关指标的衰变规律。运用以往的疲劳损伤累积模型不能准确拟合多级荷载下沥青混合料的疲劳累积损伤，预测的疲劳寿命与试验结果相差大，在此基础上提出并建立了与加载历史，加载次序相关的疲劳寿命预测方程，其预测结果比以往的疲劳寿命预测模型更准确，引入加载历史和加载次序作为疲劳损伤参数更具有优越性。采用数字散斑相关（DSCM）测量系统，基于Matlab平台结合分形理论数值计算方法自行编程，对多级荷载作用下沥青混合料疲劳损伤累积的宏观体现-裂缝的发展规律进行研究，揭示了荷载转换时疲劳损伤累积途径的变化；同时通过改变低-高应变水平加载次数的比例，确定沥青混合料在低-高加载模式下存在“锻炼效应”，通过以上研究对多级等幅荷载变换时疲劳损伤出现延迟现象给出了合理的解释。深入分析了多级荷载作用下沥青混合料的疲劳损伤累积规律，并对基于疲劳累积损伤的沥青混合料破坏进行了研究，结果表明加载历史与加载顺序对沥青混合料疲劳破坏的影响较大；在此基础上，尝试建立了一种能反映损伤现状以及加载历史、加载次序相关的基于非线性疲劳损伤累积的沥青层破坏评价的新体系，实例分析表明，它比现有的基于Miner线性准则建立的疲劳破坏评价体系更能反映路面沥青层的实际情况。本文研究所取得的成果有助于人们进一步认识沥青路面在荷载作用下的疲劳损伤累积规律，为以沥青层层底拉应变作为控制指标的沥青层破坏体系的建立奠定基础，对于完善沥青路面疲劳设计方法，提高沥青层的耐久性设计水平具有重要意义。
[Abstract]:Fatigue damage is one of the main failure types of asphalt pavement, the asphalt pavement structure design is the key problem. And the asphalt mixture of asphalt pavement as the main building materials, the research process and the cumulative fatigue life prediction is one of the key problems need to research and an important means to solve the fatigue damage of asphalt pavement in the traffic load. Under the fatigue damage. Based on the National Natural Science Fund Project "asphalt pavement random fatigue cumulative damage mechanism research (51038004), four point bending fatigue test by Qu Xiaoliang under different loading modes, reveal the variations of the performance parameters of asphalt mixture, the stiffness modulus decay associated with loading history and the order of the asphalt mixture based on nonlinear fatigue damage, for improving the fatigue design of asphalt pavement structure with the existing It has important scientific reference value.
By four point bending beam fatigue test of single loading, 4 strain at the level, and put forward the method of determining the initial stiffness modulus and failure criterion, gives a prediction equation of single stage load and stiffness modulus and strain fatigue life of asphalt mixture, and the analysis of the attenuation law of tensile strength the bending stiffness modulus under different strain levels, set up and loading times, cumulative damage model of power function fatigue loading size and stiffness modulus of the asphalt mixture, determine the fatigue damage evolution is a nonlinear characteristic.
By fatigue test of multistage constant load under different loading modes, obtained in different load size, tensile stiffness modulus and bending under different loading times under different order of loading, the dissipated energy decay law related index change rate of fatigue damage. Fatigue damage of asphalt mixture using fatigue damage cumulative model can not accurately fitting the past under multi load, fatigue life prediction and the experimental results of the difference, then put forward and established with the loading history, fatigue life prediction equation of loading order, the prediction results of fatigue life prediction model than previous work more accurate, introducing loading history and loading sequence as fatigue damage parameters has more advantages.
Using digital speckle correlation (DSCM) measurement system, calculation method of self programming numerical Matlab platform based on the fractal theory, studied the development regularity of the macro - reflect the multi-stage loadings of asphalt mixture under fatigue crack, variation of load conversion when the fatigue damage cumulative way; at the same time by changing the low high the strain level times of loading ratio, determine the asphalt mixture at low and high load mode exercise effect, through the above research on fatigue damage of multi level amplitude load transform time delay phenomenon was explained.
The in-depth analysis of the accumulation of fatigue damage of asphalt mixture and multi-stage loading on asphalt mixture fatigue damage based on the damage were studied. The results show that the loading history and loading sequence has great effect on the damage of asphalt mixture fatigue; on this basis, an attempt to reflect the damage status and the loading history was established the new system, loading order nonlinear fatigue damage of asphalt layer damage evaluation based on the analysis of an example shows that it is the Miner linear fatigue damage criterion evaluation system can reflect the actual situation of asphalt pavement layer based on existing.
The achievements of the dissertation are helpful in understanding the fatigue damage of asphalt pavement under the load accumulation, is at the bottom of the asphalt layer tensile strain as the control index of asphalt layer destruction has established the foundation for improving the asphalt pavement, fatigue design method, which is of great significance in improving the durability design level of asphalt layer.

【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U414;U416.217

【参考文献】