Application of GPR reverse time migration in tunnel lining cavity imaging
- PDF / 985,528 Bytes
- 8 Pages / 595.22 x 842 pts (A4) Page_size
- 33 Downloads / 207 Views
Application of GPR reverse time migration in tunnel lining cavity imaging* Lv Yu-zeng1,2, Wang Hong-hua♦1,2, Gong Jun-bo1 Abstract: Correctly locating the tunnel lining cavity is extremely important tunnel quality inspection. High-accuracy imaging results are hard to obtain because conventional one-way wave migration is greatly affected by lateral velocity change and inclination limitation and because the diffracted wave cannot be accurately returned to the real spatial position of the lining cavity. This paper presents a tunnel lining cavity imaging method based on the groundpenetrating radar (GPR) reverse-time migration (RTM) algorithm. The principle of GPR RTM is described in detail using the electromagnetic wave equation. The finite-difference timedomain method is employed to calculate the backward extrapolation electromagnetic fields, and the zero-time imaging condition based on the exploding-reflector concept is used to obtain the RTM results. On this basis, the GPR RTM program is compiled and applied to the simulated and observed GPR data of a typical tunnel lining cavity GPR model and a physical lining cavity model. Comparison of RTM and Kirchhoff migration results reveals that the RTM can better converge the diffracted waves of steel bar and cavity to their true position and have higher resolution and better suppress the effect of multiple interference and clutter scattering waves. In addition, comparison of RTM results of different degrees of noise shows that RTM has strong anti-interference ability and can be used for the accurate interpretation of radar profile in a strong interference environment. Keywords: Tunnel lining cavity, ground-penetrating radar (GPR), reverse-time migration (RTM), zero-time imaging condition
Introduction With the rapid development of infrastructure construction, the scale of tunnel construction in China is expanding continuously. Common issues in tunnels are lining cavity, emptying, and cracking due to the tunnel construction technology, construction environment, and supervision strength. Lining cavity easily causes lining damage, leakage, and other engineering problems (Zhang
et al., 2010; Wu and Hua, 2017). Therefore, the detection of tunnel lining cavity is important to identify tunnel safety quality problems and perform maintenance and repair in time. Conventional detection methods of tunnel lining quality do not meet the needs of engineering testing because of their low precision and efficiency and destructive effect on tunnel lining (Wu et al., 2008). As a shallow geophysical method that uses highfrequency electromagnetic wave, GPR has been widely
Manuscript received by the Editor May 20, 2019; revised manuscript received May 7, 2020. 1. College of Earth Sciences, Guilin University of Technology, Guilin 541004, China. 2. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin, 541004, China. ♦Corresponding author: Wang Hong-hua (Email: [email protected]) © 2020 Chinese Geophysical Society. All rights reserved.
277
Application of GPR reverse time migrat
Data Loading...
