小净距交叉隧道爆破方案研究

Research of Blasting Scheme for Cross Tunnel with Small Clearance

新建隧道从既有铁路隧道上方穿过,形成空间立体交叉隧道,两隧道最小净距为1.365 m.新建隧道在距交叉点10 m以外采用方案一爆破施工,10 m以内采用方案二爆破施工,同时对既有铁路隧道衬砌进行了振速监测,以期指导新建隧道的爆破施工.研究表明,这两种不同的爆破方案,有效地减弱了新建隧道爆破振动对既有铁路隧道的影响,在满足既有铁路隧道衬砌安全的情况下,新建隧道最终安全通过小净距段,且没有影响工期;同时,研究发现,径向振动速度最大,且频率较低,属易破坏方向.

The newly-buih tunnel generally crosses the existing railway tunnels from top part, forming a three-di- mensional crossed tunnels, the minimum clearance is required to be 1. 365m. When distance is 10m away from crossing point, the first scheme is adopted to blast, otherwise, the second scheme is adopted and simultaneously, the vibrating velocity of existing railway tunnel lining was monitored to guide the new tunnel blasting construc- tion. The research shows that the two different blasting schemes can effectively weaken impact on existing tunnel, namely requirement on safety can be met with tunnel crossing the minimum clearance, and construction can be finished without delay. Furthermore, the research also shows that the in radial direction, vibration velocity is the largest, the frequency is lower, which is a direction easy to be damaged.