Performance Analysis and Related Data Utilization of Rapid Crack Inspection Technology for Railway Tunnel Lining Surface

Abstract

As an important means, the vehicle-mounted imaging technology is usually used to acquire the status data of cracks on lining surfaces of large-scale railway tunnels in operation. Taking a 4 km railway tunnel as a test sample, this paper firstly verified the performance of a vehicle-mounted lining crack inspection system, and analyzed the key performance parameters such as crack inspection rate, length recognition accuracy, mileage positioning error, etc. After its effectiveness was verified, the inspection system was used to inspect the lining cracks of operation railway tunnels with total length of 55 km. The test results show that 60% of cracks with the width of less than 0.3 mm could be inspected, while the figure for the cracks with the width of more than 0.3 mm was 93%. At the confidence level of 90%, the errors in crack mileage and longitudinal crack length are ±0.8 m and ±0.7 m respectively. There exists splicing redundancy between circumferential cracks, and the error is proportional to the number of channels spanned by the cracks. The statistics of lining cracks of operation railway tunnels with total length of 55 km show that circumferential cracks, longitudinal cracks, oblique cracks and water seepage cracks accounted for 55%, 23.1%, 16.9%, and 1.5% of the total, respectively. According to the lining crack state assessment criteria, single-inspected cracks are classified as those that need "focus" and "attention" respectively. In consideration of the impact of crack shapes on the lining structure safety, data utilization strategies for different types of cracks are proposed in this paper.