地质雷达非接触式车载系统隧道衬砌检测影响因素研究

Research on the Influential Factors of Lining Detection by Non-Contact GPR Vehicle-Based Detection System

借助模型试验和现场试验,文章针对地质雷达由传统接触式检测技术到非接触式多通道检测技术的几个关键技术问题进行探索研究,重点研究了非接触式地质雷达车载系统检测距离、检测速度及天线选型对检测结果的影响。研究结果表明:(1)检测距离为200 mm时效果较好,地质雷达信号经过水平滤波去背景、垂向滤波增益处理后能够形成清晰的雷达图,能较准确判识隧道衬砌质量缺陷,衬砌厚度检测精度可达±3 cm;(2)检测速度为20km/h时,雷达扫描图像清晰,既能保证隧道状态检查车载系统有较好的隧道病害发现能力,又能保证较高的检测效率;(3)对于隧道底部的病害判识,400 MHz空耦天线得到的雷达图,层位清晰,病害显现明显,比400 MHz屏蔽天线检测效果更好;(4)采用400 MHz+900 MHz组合天线进行互相校正时,绝大多数病害在地质雷达图上能够反映出来,应用不同频率天线组合方式是提高车载平台检测系统效率和准确度的有效途径。该研究成果能为我国地质雷达多测线非接触式车载平台检测系统的研制提供重要的技术参考。

Based on numerical modeling and field testing, this paper discusses several key technical problems of Ground Penetrating Radar （GPR） regarding the change from traditional contact detection technology to non-contact multi-channel detection technology, especially the influences of detection distance, detection speed and antenna se- lection of non-contact GPR technology on detection results. The following can be observed from the results： 1） 200 mm is the best detection distance, from which the geological radar signal can form an entire clear radar graph to identify lining quality defects by employing horizontal high-pass filtering, eliminating background and vertical filter- ing gain. From the radar graph, a tunnel lining defect can be accurately identified, with a lining thickness detection precision of ＋3 cm; 2） with a detection speed of 20 km/h, the radar graph is clear and the vehicle-based system per- forms well in both defect identification and detection efficiency; 3） For defect identification at the bottom of the tun- nel, 400 MHz horn antenna can obtain a clearer hierarchy and defect image than the 400 MHz shielded antenna; 4） Most defects can be identified by the GPR graph by applying combined 400 MHz＋900 MHZ antennas using mutual rectification. Employing antennas of different frequencies is effective to improving the efficiency and precision of the vehicle-based detection system. This research provides an important technical reference for the development of the non-contact GPR vehicle-based detection system in China.