复杂地质条件下大跨度隧道洞口爆破优化设计

Optimized Design of Large Span Tunnel Entrance Blasting Under Complicated Geological Conditions

针对一条大跨度隧道洞口爆破施工中的问题进行分析,指出软弱围岩的物理性能和隧道洞口偏压浅埋的复杂地质因素是影响洞口爆破开挖效果的关键因素。在保障洞口安全和不影响施工进度的基础上,制定出合理利用介质丰富结构面,采用小间距、弱装药的优化原则,对爆破参数和施工工艺进行调整,并结合实际试爆、监测等手段对爆破方案进行优化设计。从优化实施结果来看,工作面爆破效率、隧道周边轮廓控型、质点振动最大速度、爆破飞石控制等均取得良好效果。

In a large span tunnel blasting engineering the physical properties of weak surrounding rock and com- plex geological condition of low-buried and unsymmetrical pressure in tunnel entrance were thought to be the key fac- tors of affecting blasting excavation. The optimal principle, including rational use of media rich structural surface, small spacing and charge,were put forward based on tbe tunnel entrance safety and the construction scbedule. Ac- cording to the optimal principle, the blasting parameters and construction technology were adjusted. Then the optimal blasting scheme was designed combined with actual testing and monitoring data. The blasting effect was improved from the optimized results, such as the blasting efficiency of working surface, the outline control of tunnel surround- ing, the max velocity of particle vibration and blasting fly rock.