Experimental study on influence of blasting construction on secondary lining structure of tunnel

In order to investigate the effect of blasting vibration construction on the secondary lining of tunnel, blasting vibration tests were carried out on self-made concrete blocks with different strength at different ages and different distance from explosive source blasting in Laomuyu No.2 Tunnel of Zhangjiajie, Hunan Province. First, the influence degree of blasting vibration on each factor was judged by orthogonal tests. Then, the ultimate load of concrete blocks with different strength was measured by pressure testing machine. Finally, the influence of blasting vibration on the secondary lining was analyzed by the change rule of compressive strength of concrete blocks. The test results show that the concrete strength is the main factor to resist blasting vibration. Under the condition of stage IV surrounding rock bench construction, the C45 strength concrete at 60 m from the blasting center in 24 hage period is least affected by blasting. The strength reduction ratios of C30, C35, C40 and C45 are 21.1%, 16.8%, 13.2% and 11.0% respectively at 15 m of the detonation center distance, which are much larger than those of C30, C35, C40 and C45 at 60 m of the detonation center distance by 4.1%, 3.1%, 2.2% and 2.1%. © 2020, Central South University Press. All rights reserved.