在役公路沥青路面隐含裂缝孕育机理及无损感知识别

Asphalt pavement cracks are difficult to spot directly. The crack is unpredictable and destructive, which makes it the bottleneck of highway engineering. Research on the inoculation mechanism and nondestructive perception recognition of asphalt pavement crack has always been the concern of researchers. Through the physical mechanics and acoustic emission test, this project research establishes the correlations between time domain of acoustic emission and time of micro-cracking damage, reveals the temporal and spatial evolution characteristics of concealed crack in micro-cracking damage and explores the precursory information of micro-cracking damage. Based on that, this research also applies particle flow theory and PFC numerical simulation platform to carry out PFC acoustic emission simulation analysis on asphalt pavement concealed crack in micro-cracking damage, reveals the inoculation mechanism of concealed crack in operation highway asphalt pavement on microscopic scales. In addition, the research combines site test results to analyze the dynamic response and attenuation characteristic of acoustic emission signal of concealed crack in cracking damage on macroscopic scales and establishes three dimensional nondestructive perception recognition algorithm of concealed crack in operation highway asphalt pavement according to elastic wave propagation theory, so as to achieve precise localization of potential micro-cracking areas before having macro cracks. The result of this project research will serve as the scientific basis for improving current pavement nondestructive testing technology, the accuracy of pavement performance testing, monitoring, evaluation and medium and long term performance prediction.

沥青路面隐含裂缝由于很难直观表现出来，其不可预测性及严重破坏性一直是公路工程界的瓶颈问题。对沥青路面裂缝孕育机理及无损感知识别的研究一直受到研究人员的关注。本项目研究通过物理力学与声发射试验，建立声发射时域与微开裂破坏时间的相关关系，揭示隐含裂缝微开裂破坏时空演化特征，探究微开裂破坏的前兆信息。在此基础上，应用颗粒流理论和PFC数值模拟平台开展沥青路面隐含裂缝微开裂破坏的PFC声发射模拟分析，从细观尺度上揭示在役公路沥青路面隐含裂缝孕育机理。同时，结合现场试验结果，分析宏观尺度上隐含裂缝开裂破坏声发射信号的动力响应以及衰减特性，并根据弹性波传播理论，建立三维问题的在役公路沥青路面隐含裂缝无损感知识别定位算法，实现宏观裂缝出现前潜在微开裂区域的精准定位。项目研究成果将为改进现有路面无损检测技术，提升路面性能检测、监测和评价，中长期性能预测精度提供科学依据。

沥青路面隐含裂缝由于很难直观表现，其不可预测性及严重破坏性一直是公路工程界的难题之一。本项目开展了不同温度下沥青混合料材料的损伤声发射特征参数研究，提出了以声发射振铃计数和幅值的变化趋势表征沥青混合料试件内部微裂纹数量和裂纹扩展程度的裂缝尺度表征方法。建立了声发射时域与微开裂破坏时间的映射关系，揭示了隐含裂缝微开裂破坏时空演化特征。探究了微开裂破坏的前兆信息。声发射累积能量在沥青混合料试件峰值荷载来临前出现明显突变下降，沥青混合料试件内部微裂纹快速发展，将累积能量变化速率第一次下降和幅值、振铃计数的整体升高现象共同作为试件破坏的前兆特征。为了研究裂缝扩展过程及空间形态演化规律，利用沥青混合料数字图像和Particles and cracks Analysis System (PCAS)，提出了一种图像识别辅助建模方法，快速建立了基于二维图像的沥青混合料数值模型。开发的模型可描述沥青混合料组分分布和评价沥青混合料的力学行为，图像识别测定的粒度分形曲线与实际级配相关性良好，通过二维数值模型能够明显地观察裂纹的定位和扩展。试件的裂纹首先在集料-砂浆界面上出现，于试件中上部发生脆性的剪切破坏，并沿着破裂面逐渐扩展。结合现场试验结果，分析宏观尺度上隐含裂缝开裂破坏声发射信号的动力响应以及衰减特性，通过信号分布区域预测损伤位置，对沥青混合料材料内部裂纹位置的定位方法进行了优化，实现了宏观裂缝出现前潜在微开裂区域的定位。本项目的研究成果可为改进现有路面无损检测技术，提升路面性能检测、监测技术水平提供科学依据。