二次喷护时期选择是隧洞新奥法施工中的重要课题，而爆破振动对二次喷护结构的影响是选择时需要考虑的重要因素。结合雅砻江锦屏二级水电站4#引水隧洞爆破开挖，采用动力有限元模拟和与现场监测数据对比的综合方法，研究爆炸荷载和开挖面初始应力瞬态卸荷耦合作用下不同龄期喷射混凝土的动力响应。研究结果表明：对于高地应力条件下深埋隧洞爆破开挖，爆破振动作用下混凝土喷层破坏是爆炸荷载和开挖面上初始应力瞬态卸荷耦合作用的结果，喷射混凝土破坏以剪切破坏为主；对于1 ~ 3、3 ~ 7、7 ~ 28天龄期的混凝土喷层，距掌子面安全距离分别是24 m、13m和9m。建议锦屏二级引水隧洞二次混凝土喷护施工滞后掌子面6个开挖进尺。

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.