Tunnel monitoring system with wireless sensor network

摘要

Long-term monitoring of distorted railway tunnels, such as that of inner space displacement, is normally carried out based on manual measurement. As the measurement work has to be carried out within limited timeframes, mostly in the middle of the night, it is difficult to obtain measurement data at short intervals. On the other hand, the introduction of automatic monitoring methods, which is effective to solve the problem described above, necessitate a huge amount of work and expense for installing and maintaining cables as well as costly equipment, especially in the tunnels which are usually long in the longitudinal direction.Therefore, this research developed a monitoring method using a wireless sensor network in order to lighten the data acquisition workload and reduce the costs for monitoring railway tunnels. The end devices of wireless sensor system are compact and light with power saving and can be used with batteries. A small data logger unified with coordinator, which operate with batteries, was developed to apply this system to the site where it is difficult to prepare electricity. A relay method was also proposed for transmitting the data over a long distance. The performance of the monitoring system was verified by means of field monitoring in two actual railway tunnels.