倾斜炮孔在大断面高强度围岩洞室开挖中的应用

Application of Inclined Blast Hole in Excavation of Large Section and High Strength Surrounding Rock Cavern

高强度围岩隧洞掘进过程中炮孔利用率低,是造成钻爆循环进尺较小的重要因素,增加了施工成本,延长了施工工期。对于大断面高强度围岩隧洞掘进施工,通过改变布孔方式,可显著地提高炮孔利用率,增大钻爆循环进尺,降低施工成本。本文以四川双江口水电站尾水调压室顶层、尾水洞等大型洞室为依托,通过对洞室钻爆施工工艺技术进行优化创新,全断面炮孔(周边孔除外)采用倾斜孔布孔方式,将炮孔利用率由80%左右提高到95%以上。大断面高强度围岩隧洞掘进采用倾斜孔布孔方式,在节能环保、降低施工成本,提高施工效率等方面取得了良好的效果,可为同类大断面高强度围岩隧洞钻爆施工提供实践经验。

n the process of high-strength surrounding rock tunnel excavation,the low utilization rate of blast hole is an important factor that causes the small drilling and blasting cycle footage,which increases the construction cost and prolongs the construction period.For the tunneling construction under the condition of large section and high strength surrounding rock,the utilization ratio of blast hole can be significantly increased,the drilling and blasting cycle footage can be increased,and the construction cost can be reduced by changing the mode of hole layout.Based on the large-scale caverns such as the top floor of tailrace surge chamber and tailrace tunnel of Shuangjiangkou Hydropower Station in Sichuan Province,this paper optimizes and innovates the drilling and blasting construction technology of caverns,and adopts inclined holes layout for full section blast holes(except the peripheral holes),so that the utilization ratio of blast holes is increased from about 80%to over 95%.The inclined hole layout method is adopted in the excavation of large section and high strength surrounding rock tunnel,which has achieved good results in energy saving,environmental protection,construction cost reducing,and construction efficiency improving,etc.,and can provide practical experience for the drilling and blasting construction of similar tunnels.