全波场映像技术以及其在高速公路路基缺陷检测中的应用

针对高速公路运营中的路基长期稳定性问题,研发了检测高速公路路基缺陷的全波场映像技术,即一种无损检测技术,主要由单点激发-单点接收的数据采集系统和三维全波场成像系统组成。为评价该技术应用于高速公路路基缺陷检测的准确性,首先使用有限元动力分析方法进行三维数值模拟。在研究三维缺陷模型中全波场传播特性的基础上,对响应波形的频谱特征进行详细分析,在此基础上合成的成像图显示缺陷区域位置与其在模型中的位置及区域大小相吻合。然后在实际预先设置缺陷的等比例高速公路路基模型上开展试验验证,试验结果证明了该技术的准确性,及其在检测高速公路路基缺陷区域及位置上有良好的应用空间。

Full-wave Field Imaging Method and Its Application in Highway Subgrade Defect Detection

Nowadays in China, with increases in the lengths of new highways and the resultant increasing construction times, many personal injuries have occurred as a result of the structural defects such as track-plate fracture, through-cracks, layer alienation gap, and pulping. Investigating the damages of highway structures is an important and difficult subject, especially for defect diagnosis in a structure''s support plate and subgrade surface layer. As various current subgrade defect detection methods are limited and ineffective, how to detect faults quickly and accurately is an important issue in civil engineering. In light of the permanent stability of the subgrade of an operational highway, a full-wave field imaging method was developed to detect defects in a highway subgrade. This detection method was a non-destructive testing method based on the characteristics of high-speed highway structures and the existing level of detects. The detection system was composed of a data acquisition system and an imaging system. The data acquisition system utilized a single-point source and a single receiver, in which three-dimensional full-waveforms were created, received, and recorded. First, to evaluate the feasibility of the method to reveal defects, a 3D numerical simulation by a finite-element dynamic method was adopted based on the theory of elastic wave propagation. Using a 3D numerical model, the characteristics of a full-wave field within some defects were studied, then the amplitude and frequency spectrum of the multi-directional response waveforms were analyzed. Based on the synthetic image, the defects were revealed and their locations and sizes agreed well with those of the numerical model. Second, a real full-scale highway subgrade model with pre-setting defects was casted, and relative tests were carried out on it. The size and location of defects revealed by the field experiments were similar to that of the actual model. The accuracy of the full-wave field imaging method proved to meet the detection requirements, such as easy maneuverability and rapid speed of detection. It is concluded that the full-wave field imaging method has high potential in providing quick and effective detection of defects in highway subgrades.