Application of the Rebound Method and the 3D Laser Scanning Technology in the Health Detecting of Metro Line Structure

The rebound method is used to detect the metro line new foundation pit concrete structure, and the position and spacing of the rebar are detected by using the rebar detector. The carbonization depth of concrete surface was measured by 1% phenolphthalein alcohol solution and carbide depth gauge, and resilience instrument is used to measure the rebound value of concrete. The concrete strength conversion value is obtained based on the average rebound value and the average carbonization depth, then the concrete strength is calculated. Through on-site detect, the factors influencing the accuracy of concrete strength and the measures to improve the accuracy of the test are summarized. 3D laser scanning technology combined with the artificial method is used to measure the structure plane and section of the metro, and its use status is then investigated. The detect and current situation investigation results indicate that the concrete strength of metro structure station and interval tunnel conforms to the original design requirements, there are whereas peeling, cracking, seepage and other damages existing in the metro structure. The results can provide reference and basis for the health assessment of metro structure.