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 Ministry of Education，Wuhan University，Wuhan，Hubei 430072，China
Abstract：Choosing appropriate time for the construction of the permanent shotcrete is a key subject in the New Austrian Tunneling Method (NATM), while the influence of blasting vibration on the shotcrete is an important influencing factor. For the blasting excavation of the 4# diversion tunnel in the Jinping-II Hydropower Station, dynamic responses of the shotcrete at different ages, which induced by the coupling action of blasting load and transient releasing of excavation load, are investicated with combined methods of the numerical simulation and the site monitoring. Results show that the shotcrete failure in blasting excavation of deep- buried tunnels is resulted from the coupling of the blasting load and the transient releasing of excavation load on high ground stress. The main failure mechanism is the shear failure mode. With regard to the shotcrete at different ages of 1 ~ 3 days, 3 ~ 7 days and 7 ~ 28 days, the safety distance from the tunnel face are 24 m, 13 m and 9 m respectively. The permanent shotcrete is suggested to be constructed behind the blasting face 6 excavation footage.
赵振国1，2，杨建华1，2，卢文波1，2，严 鹏1，2，陈 明1，2. 基于爆破振动影响评价的深埋隧洞围岩二次喷护时期选择[J]. 振动与冲击, 2015, 34(7): 8-14.
ZHAO Zhen-guo1，2，YANG Jian-hua1，2，LU Wen-bo 1，2，YAN Peng1，2，CHEN Ming1，2. Selection of sprayed time for permanent shotcrete based on evaluation of blasting vibration impact in deep-buried tunnels. JOURNAL OF VIBRATION AND SHOCK, 2015, 34(7): 8-14.
