Abstract:

Ground penetrating radar is one of the important means to test the quality of the tunnel lining. However, there are some problems in the testing of the tunnel lining by means of ground penetrating radar. In the paper, the basic working principle of tunnel lining testing by means of ground penetrating radar is presented, and some measures in terms of gain setup, defect identification, interfered image identification, lining thickness testing and position determination are proposed. Conclusions drawn are as follows: 1) The gain setup should be made as far as possible at places where the compactness of the shotcrete on the side wall is good, and it should be far away from the interfering obstacles inside the tunnel; 2) Regarding the identification of the defects and the interfered images, experience should be accumulated constantly in the site testing and indoor analysis; 3) Average wave velocity method, assisted by mini electrical depth measuring method, can be used to test the lining thickness, and the absolute error of the lining thickness measured by average wave velocity method can be controlled at 5 cm; 4) Time trigger method should be used in tunnel lining quality testing, the radar antenna should be kept moving at a constant speed as far as possible, and good records should be made.

Key words: ground penetrating radar, tunnel lining, quality inspection