基于分布式光纤形状传感的沥青混合料车辙变形监测研究

Monitoring Rutting Deformation of Asphalt Using Distributed Optical Fiber Shape Sensing Technology

车辙是沥青路面典型的病害形式,其现有的检测及评估方法大多存在表观性。因此,对沥青路面结构内部车辙的演变过程、横断面形状进行监测和评估具有重要意义。引入分布光纤形状传感技术,研发了可用于沥青路面的柔性分布式光纤形状传感器,通过理论分析和标定试验明确了其形状测试原理。将分布式光纤形状传感器植入车辙试件,采用光频域反射设备(OFDR)对室内车辙试验进行了加载全过程的实时监测,获取了沿车辙横断面上各测点的时程应变数据。进而,采用空间曲线理论中的Frenet-serret方程,提出基于分布式光纤传感技术的车辙横断面二维形状重构算法,得到发生累积变形时分布式光纤形状传感器的形态演变曲线。提取重构曲线中荷载作用位置处的位移与车辙仪位移传感器数据进行对比,平均相对误差仅为0.981%,证实上述方法可以实现车辙变形的准确监测。最后基于重构得到的车辙横断面形状,分析车辙变形的演变规律,结果表明其与沥青路面永久变形发展阶段中的压密、流动过程具有较好的对应关系。创新性地提出了基于分布式光纤形状传感技术的沥青混合料车辙变形监测方法,有助于明晰沥青路面结构内部车辙类病害的发展规律和横断面形态,为道路基础设施全寿命周期内服役性能的评估和管养提供了新思路。

Rutting is a typical form of asphalt pavement disease.Most existing methods for the detection and evaluation of rutting focus on the pavement surface.However,the rutting process must be monitored by evaluating the cross-sectional shape of the asphalt pavement structure as well.A flexible distributed optical fiber shape sensor for asphalt pavement was therefore designed and developed in this study.The proposed sensor was embedded into a rutting specimen and its response during the entire loading process of a rutting test was monitored in real time using an optical frequency domain reflection device(OFDR)to obtain the time-history strain data at each measurement point along the rut cross-section.The Frenet-Serret equation from space curve theory was subsequently applied to propose a reconstruction algorithm for the two-dimensional shape of the rutting cross-section.The shape evolution curve provided by the distributed optical fiber shape sensor was obtained as the cumulative deformation occurring during loading.By comparing the displacement data for the load action position with the displacement sensor data from the rutting instrument in the reconstruction curve,the average relative error was determined to be only 0.981%,proving that the proposed method can accurately monitor rutting deformation.Finally,the rutting deformation evolution law was analyzed based on the reconstructed cross-sectional shape.The results indicated that rutting deformation exhibits a close relationship with the asphalt pavement compaction and flow processes during the permanent deformation development stage.The proposed method for monitoring the rutting deformation of an asphalt mixture using distributed optical fiber shape sensing technology will help to clarify the law reflecting the development of rutting disease and cross-sectional shape change in asphalt structures,providing a novel approach for the service performance evaluation and maintenance of road infrastructure throughout its entire life cycle.