Model Test And Engineering Application Of Ground-penetrating Radar For Road Subgrade Diseases

Since the 12^th Five-Year Plan,China's comprehensive transportation system has initially formed an integrated transportation network with"five vertical and five horizontal"as the skeleton.However,road collapse accidents become more and more frequent along with road development,which poses a great threat to people's travel safety and life and property.In the past,the core sampling method can only take sample point detection.Not only does it have long detection cycle,poor representativeness,low efficiency,but also causes damage to roads,failing to meet the modern demand for road detection.Ground-penetrating radar detection has seen a rapid development of non-destructive testing in recent years.Its detection avoids damage to the structure,speeds up the detection speed,increases the detection surface,and improves the reliability and accuracy of highway quality evaluation.In addition,radar technology can detect internal disease and steel distribution,avoid excavation,and provide more effective road management information.In this paper,the size,depth,filling and antenna scanning speed of different voids are studied by model box test.The layered structure of roads,road-related diseases,different shape voids,different steel bars spacing,and the diameter of the steel bar are simulated by GprMax and Matlab programs.And the radar waveforms were analyzed and compared.The main contents are as follows:?1?By embedding different media,different sizes and different fillers in the test model box,the corresponding radar map features are obtained.According to the characteristics of the radar map,the depth of the target body,whether it is filled with water,and the diameter of the target body are calculated.?2?Study the influence of detection by metal pipe,steel bar diameter and steel bar spacing,which concludes that the metal has a great influence on the radar detection.When the metal pipe is too large,the spacing of the steel bars is too small,or the spacing of the steel bars is too large,these conditions will directly affect the quality of the detected image of the target below,or even overlook it.?3?Simulate the waveforms corresponding to different shapes and sizes of holes by software,and provide a library of different cavity shapes for the detection;the effects of different antenna frequencies on imaging and resolution are studied;the difference between the simulated aeration cavity and the water-filled cavity is confirmed by the experimental data.It simulates the situation of various diseases in the road,looseness,hollowing,damage of expansion joints and pipelines in the road,which is convenient for the preliminary interpretation of the radar detection map in actual operation.?4?Apply radar detection technology to the detection in a certain road in Sichuan,analyze the disease in the map according to the waveform characteristics of the simulated road disease,and finally excavate a cavity.The position of the cavity and the position of the radar anomaly are completely consistent with each other,which confirmed the test results.