Effect of Blasting-Induced Vibration on Adjacent Brick Masonry Structures

As blasting is widely used in underground excavation in rock, the damage to adjacent buildings caused by blasting-induced vibration has attracted increasing attentions in both academic research and engineering applications. Blasting vibration wave imposes cyclic loadings on adjacent buildings and structures with a combined loading mode of tension, compression, bending, shear and torsion, and it leads to flaking of floated coat, wall cracking, developing of original cracks, etc. This paper presents a blasting case study for the excavation of Wucun tunnel in Xiamen Success Avenue. It is now the longest urban road tunnel with a length of 3700m in China. The open excavation section of the tunnel has a maximum depth of 25 m and a maximum width of 50m. The tunnel passes areas with complex geological conditions. There are two brick masonry structures which are only about 3m away from the excavating sideline. Field monitoring of the blasting-induced vibration and cracks in the two brick masonry structures (i.e., a one-story building and a three-story building) adjacent to the excavation were conducted, which will be described first. Then damage characteristics of brick masonry structures and crack propagation law are presented and discussed. It is found that the damage caused by blasting-induced vibration of the multi-story masonry structure mainly focus on the ground floor. Crack width had not obvious change on the day of blasting, while blasting-induced vibration led to crack propagation continuously in general. More cracks will appear and the original cracks will extend shortly because of the cumulative damages caused by multiple blasting-induced vibration.