城市硬岩隧道减振爆破直眼掏槽技术应用及实践

Case Study on Parallel Cut in Vibration-reducing Blasting of Hard Rock Tunnel in Urban Area

在城市隧道掘进爆破施工中,掏槽方式的选择,不仅影响掘进速度,同时也影响爆破振动效果。为将青岛地铁一期工程3号线3标段下穿建筑物时爆破振动影响程度降到最低,选取该标段下穿济南军区第一疗养院口腔科医院段作为试验区段,对小直径单中空直孔掏槽、大直径单中空直孔掏槽和大直径双中空直孔掏槽3种掏槽形式的掘进进尺、炮眼利用率和爆破时掌子面正上方地表质点振动速度峰值进行数据统计分析。从中得到以下结论:1)同等条件下,大直径单中空直孔掏槽在炮眼利用率、减振效果方面优于其他2种掏槽形式,采用该掏槽形式,顺利通过了试验区段的施工,且振动速度控制在2 cm/s内;2)直眼掏槽掘进及减振效果与装药眼距中空孔边沿距离l与中空孔孔径ф的比值相关。

Cut method not only affects the tunnel excavation efficiency,but also affects the blasting vibration control effect.No.3 bid section of No.3 line of Phase 1 project of Qingdao Metro crosses underneath an existing hospital.In the paper,the blasting in the tunneling under the hospital is studied.3 parallel cut methods,i.e.,small-diameter single hollow hole cut method,large-diameter single hollow hole cut method and large-diameter double hollow hole cut method,are analyzed in terms of tunneling advance rate,blasting hole utilization rate and peak value of vibration velocity of monitoring point at ground surface above the working face.Conclusions drawn are as follows：1） Under the same conditions,the large-diameter single hollow hole cut method is superior to the other 2 cut methods in terms of blasting hole utilization rate and vibration control.The large-diameter single hollow hole cut method is used in the blasting of tunnel underneath the hospital and good effect has been achieved,with the vibration velocity being controlled under 2 cm/s; 2） The tunnel excavation efficiency and vibration control effect of parallel cut method are related to the ratio between the distance from the charged hole to the hollow hole （l） and the diameter of the hollow hole （φ）.