大断面黄土隧道近距离爆破控制效果分析

Control Effect of Closed Distance Blasting in Large Section Loess Tunnel

为防止超大断面黄土隧道开挖爆破对既有隧道中人、车通行安全的影响,提出合理的爆破施工参数及控制技术。新建二庄科隧道工程,其最大开挖断面达到136.08 m^2,存在断面大、周边环境复杂、对爆破施工技术要求高等技术难点。综合考虑现场条件及工程经验,对双侧壁导坑法光面爆破施工技术进行详细设计,通过以大化小、优化施工工序、细化爆破施工参数、加固既有隧道衬砌结构等方法,有效地避免了爆破振动对既有隧道的影响,既有隧道迎爆侧振速峰值仅为4.20 cm/s,远小于规范允许值,且爆破效果也满足光面爆破质量控制要求,从而确保了大断面隧道施工安全及既有隧道的通行安全。因此,该隧道爆破控制技术及参数可为类似大断面隧道爆破施工控制提供参考。

In order to prevent the impact of excavation blasting on the traffic safety of adjacent existing tunnels in the super-large section loess tunnel, reasonable blasting construction parameters and control technology were proposed. In new Erzhuangke Tunnel, the maximum excavation section reaches 136.08 m^2, there is a large section and complicated surrounding environment and it requires high technical difficulties for blasting construction. Considering the site conditions and engineering experience, the smooth blasting of two side-wall-pilot construction technology was designed. Through the mea-sures of converting large section to small section, optimizing construction procedure, detailing design of blasting construction parameters and strengthening the lining structure of existing tunnel, the impact of blasting vibration on existing tunnel effectively reduced. The maximum vibration velocity peak of the front side of existing tunnel is only 4.20 cm/s, which is far less than the allowable value of code. The blasting effect also meets the requirements of smooth blasting quality control. So it ensures the safety of super-large section tunnel construction and the traffic of existing tunnels. Therefore, the blasting control technology and parameters of the tunnel can provide reference for the blasting control to similar super-large section tunnels.