Abstract
Subway structure safety detection is an important method to ensure the safe operation of trains. Efficient, high-precision, and automatic tunnel clearance detection is the key to ensure safe operations. This study introduces a mobile tunnel scanning system that integrates a scanner, an inertial measurement unit (IMU), and a rail car. Global Navigation Satellite System (GNSS) time and system hardware calibration are used to synchronize time and space information of the system; the attitude and speed are corrected using the control points from the tunnel to improve the accuracy of absolute positioning. The section coordinate system is converted using the control points and system calibration parameters to complete the tunnel clearance inspection, and the distance between the nearest point of the section and the clear height of the vault is given. Taking Fengxi Road’s Bashan tunnel section of Chongqing Metro Line 5 as an example, the overall system accuracy was tested. The accuracy of chord line measurements was within 1 mm, the internal coincidence accuracy of repeated measurements of the vault clear height was 1.1 mm, the internal coincidence accuracy of repeated measurements of the closest gauge point was 4.8 mm, and the system calibration accuracy was approximately 2 mm. Compared with the existing scheme, the system combines absolute measurement and relative measurement mode to judge the structural safety of tunnel section from multiple angles, high precision, and high efficiency.
Highlights
China has undergone rapid development in urban rail transit; in 1965, the first subway was built in Beijing and, by the end of 2019, the nation’s urban rail transit lines reached 6736.2 km, including5180.6 km of metro lines (76.9%)
According to the field test data, the value of the tunnel scanning system can be discussed from the following aspects
From the way of work, Leica’s SiTrack:One is integrated with scanners, inertial navigation, and odometer while Amberg’s IMS5000 integrates scanners, inertial navigation, and odometer, and adds range finder and inclinometer, and the car is designed by hand
Summary
China has undergone rapid development in urban rail transit; in 1965, the first subway was built in Beijing and, by the end of 2019, the nation’s urban rail transit lines reached 6736.2 km, including5180.6 km of metro lines (76.9%). China has undergone rapid development in urban rail transit; in 1965, the first subway was built in Beijing and, by the end of 2019, the nation’s urban rail transit lines reached 6736.2 km, including. Because of the influences of geology, stress, and groundwater changes, internal deformation will inevitably occur in tunnels at different degrees. To ensure normal subway operations and ensure the safety of people’s lives and property, it is especially important to monitor the deformation of the lining ring in a tunnel. Tunnel clearance detection is a part of tunnel deformation monitoring. To ensure that the pipeline and other accessories in a tunnel do not intrude the vehicle gauge, the normal operation of vehicles can be judged for being disturbed or damaged by the positional relationship between the gauge and objects, such as pipeline equipment in the tunnel
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