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| Damage mechanism of surrounding rocks due to repeated disturbance between blasting delays in deep tunnels |
| HE Qi1，2，YAN Peng1，2，LU Wenbo1，2，CHEN Ming1，2，WANG Gaohui1，2 |
(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，China；2. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of Ministry of Education，Wuhan University，
Wuhan，Hubei 430072，China) |
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Abstract Blasting load and geostress transient unloading are important factors influencing the development of excavation damage zone(EDZ) in deep tunnels. The blasting load and geostress transient unloading of every blasting delays were analysed，and the damage extents of surrounding rocks induced by blasting excavation were compared based on the results from the theoretical model and numerical simulation. The damage mechanism of the blasting load was found to be mainly tension or tension-shear failure and the geostress transient unloading was mainly the compression-shear failure. On the excavation face，every blasting delays had an contribution to the final EDZ which reflected the repeated disturbance and the MS7 and MS9 were the main contributors to the EDZ. The EDZ induced by every delays is not only related to the load value，but also associated with the excavation radius. In addition，the higher the geostress level，the higher influence on the EDZ that caused by geo stress transient unloading. Under the same condition of blasting parameters，the geostress level is the decisive factor to the development of EDZ during deep tunnel excavation.
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2016, Vol. 35 
