The refined numerical simulation and the field monitoring for blasting vibration analysis in tunnel in-situ expansion
GUAN Zhenchang1, LÜ Yang1, CHEN Liangbin2, LI Yongshan2
1. College of Civil Engineering, Fuzhou University, Fuzhou 350116, Fujian, China; 2. The 2nd Construction Company Ltd., China Railway Construction 15th Corporation, Shanghai 201713, China
Abstract Based on the in-situ expansion project of Jinjishan tunnel in Fuzhou 2nd ring road, the row-hole blasting was simplified to the triangular blast load and then applied upon the centerline of row-hole according to the detonator time-interval. The whole process of millisecond blast in the left head face of left tunnel was carefully studied by the refined numerical simulation, and the blast-induced vibration effect upon the surrounding tunnels was well focused. As far as pedestrian tunnel was concerned, the peak velocity of frontward side was 5~13 times to its counterpart of backward side, and the vertical-direction peak velocity at the frontward side wall reached to 4.55 cm/s. On the other hand, the vibration effect of right tunnel was negligible, since the existing cavity within left tunnel could hamper the propagation of vibration wave significantly. The field monitoring at the frontward side wall was also carried out, whose three-dimensional velocity histories generally coincided with the results from numerical simulation. The time-interval among peaks coincided with the delay of detonators, while the peak velocity was 10%~30% greater than its counterpart calculated by numerical simulation.
