Abstract
There are a number of aged railway tunnels constructed of block linings in Japan. Most materials of the block are the bricks. These tunnels have some problems in their structural integrity. An effective non-destructive test method for such problems is hence expected. We have developed a new system for tunnel concrete linings by which the thickness and whereabouts of cavities, etc. can be detected. We recently started a research to evaluate quantitatively the defects of tunnel brick linings, especially the joint loss, with this system. As the results, it was discovered that the defects of the lining could be evaluated with two numerical factors obtained from this system. One factor is maximum amplitude obtained from the wavelet transform of a sound wave of striking, and another one is a frequency where the maximum amplitude is shown. By evaluating with these factors, the structural integrity of brick linings can be immediately classified into three degradation stages.
