Tunnel drainage systems are designed depending on different framework requirements. There are tunnels designed relieved or not relieved of pressurized water. These drainage systems have to reduce the groundwater pressure on the tunnel lining and to drain off this water. But these systems often get clogged with scaled deposits. Scaled deposits caused by different factors changing the carbonate balance of the drainage water. Scaled deposits cause a lot of maintenance costs because of the necessity to employ huge manpower, cause huge material requirements and the necessity of closing down the tunnel during maintenance works. Especially after finishing building the tunnel the maintenance teams have big problems to detect and maintain critical sections of the tunnel drainage system.
At present there are no reliable monitoring systems supporting the maintenance teams to arrange efficiently maintenance schedules depending on critical sections. Neither existing tunnels nor new built tunnels have such strongly demanded monitoring systems. The awareness about this highly relevant maintenance problem and the current request for proposal resulted in the motivation to develop this missing link - a monitoring system for tunnel drainage systems.
The target is to create several packages of flexible monitoring techniques that are usable for still existing and new built tunnels. Combining different aspects of measurement and test engineering there are locally, short and long-distance measuring tools for drainage monitoring. The innovation to generate integral information about the quantity and the position of scaled deposits in the drainage system combined with the ability to use non-contacting measurement techniques is a central target and a totally new approach. In this case the drainage water does not get influenced by sensors or other measuring equipment changing the carbonate balance. It is planned to implement the generated knowledge and knowhow to evolve monitoring systems that help builder and operator of tunnels for long term and efficient planning the maintenance works and reducing the maintenance costs