Blasting Vibration Monitoring of Undercrossing Railway Tunnel Using Wireless Sensor Network

The construction blasting in a new tunnel will undoubtedly influence the structure of existing tunnel. In order to monitor the effect of the blast-induced vibration on the structure of existing tunnel, a wireless sensor network (WSN) was established, which included the blast vibration monitoring system and the wireless remote data acquisition system. An existing railway tunnel was monitored during the construction of a new tunnel in Shaanxi, China. Concrete strain and peak particle velocity (PPV) were adopted to evaluate the influence of new tunnel construction blasting on the structure of existing tunnel. The monitoring results indicated that the concrete strain was different before and after the two tunnels crossing, which was much larger in front of the excavation face, and then it decreased gradually after the crossing. The PPV at the side wall of existing tunnel toward the blasting source was quite higher, and the location of maximum PPV changes with the process of tunnel excavation. When the distance between the existing and new tunnels was 4 m, the PPV reached 11.83 cm/s, which was already beyond the safe value, so the explosive charge should be reduced.