Abstract
On the construction of very closely located twin tunnels, the blasting vibration from the second tunnel may damage the lining of the first tunnel. However, vibration data related to actual damage are very few and the relation between the magnitude of the vibration and the cracking of the concrete lining has not been discussed enough.
In this study, the blasting vibration and the crack formation on the shotcrete lining of the first tunnel were carefully recorded. The closest distance between the blasting point and the shotcrete lining surface was approximately 1.0m and the maximum vibration velocity reached to 145cm/sec. Cracking on the shotcrete lining was observed when the maximum vibration velocity exceeded 70cm/sec.
