| With the fast development of China’s railway industry, the inspection requirements of track bed defects and anomalies getting higher and higher. Nowadays the traditional methods of track bed inspection are still widely used in the assessment of track bed. These methods are ineffective, expensive, and low-precision; many of them are destructive to the railway and even worsen the damage of the track. Ground penetrating radar(GPR), which based on the electrical properties of sub-ground layers, is a new non-destructive testing electromagnetic equipment. The radar survey approach permits continuous, high speed and high resolution mapping. It has been successfully applied to the detection of shallow detailed geological structures and high-resolution hidden defects. GPR has been regularly used in the road evaluation. And it’s gradually introduced to monitor track bed conditions.Based on the principle of GPR and relevant theory of the track bed defects, this paper concentrate on the usage of GPR in the inspection of track bed. First the GPR was mounted on a train after the type selection and on-site experiment. The radar surveys in this work presented several identified symbolic image standards of common track bed defects through the data analysis and site validation. And these standards could be useful in the data interpretation.The main results of this study can be summarized as follows:1. A brief description of railway industry, the status of track bed inspection in China. Also presents a review of the development and application of GPR in track bed evaluation at home and abroad.2. Briefly outlined the system components and principle of GPR, the transmission characteristics and prosperities of electromagnetic wave. Introduce the working principle, detection abilities and performance index of GPR.3. Described the structure of roadbed and common railway roadbed disease.4. Meet the hardware demands of inspection by assembling the GPR equipment on the train after the choosing suitable GPR and determine the way and position to mount the antennas.5. Defined the parameters of data sampling. Introduced the procedure and method of GPR data procession. This research summarized symbolic image of common track bed defects after data analysis and site validation, set radar data evaluating standard, completed the high speed inspection of track bed. This study provides reliable basis for treatment of railway subgrade defects.6. Achieved good results in the practical examples by testing feasibility of the standards based on the previous identified symbolic radar image. |
