Monitoring of steel-lined pressure shafts and tunnels

A new non-intrusive monitoring method to detect the local drop of wall stiffness of shafts and tunnels at hydro plants has been developed in Switzerland. The method is based on the waterhammer wave signal and the fluid-structure interaction phenomenon. An overview is presented here of the status of the ongoing work in this field, and includes a short state-of-the-art-review, a description of the physical scale model with some tests results, and a description of an in-situ measurement system which acquires pressure records from the shaft of a pumped-storage plant in the Swiss Alps.