Japanese railway tunnels are currently inspected by using destructive testing. The inspection procedure consists of three important inspecting items, such as lining thickness, voids between a lining and the natural ground, and compressive strength. This method has difficulties in measuring accuracy, cost and Efficiency of inspection. In order to solve these problems, we have developed The Elastic-wave Transfer Function Method(ETFuM) an efficient non-destructive inspection technique which can be applied to the measurement of the above mentioned three items.
The results of a fundamental experiment and a site test on ETFuM demonstrated the high feasibility of the practical application of this method to the railway tunnel inspection in the near future.