小断面隧道三臂凿岩机直眼掏槽光面爆破技术及其应用

Smooth Blasting Technology and Application of Straight Hole Cutting with Three-Arm Rock Drill in Small Section Tunnel

以某铁路隧道断面尺寸为6.5 m×6.5 m的平行导洞为例,针对三臂凿岩机在隧道内因空间限制无法实现斜眼掏槽及爆破后通风时间长等工程实际问题,提出一种三臂凿岩机直眼掏槽光面爆破技术,并进行爆破参数设计研究与应用。结果表明:该爆破方案平均循环进尺2.8~3.0 m,炮孔利用率为93%~96%,开挖轮廓壁面平整光滑,爆破循环之间未出现明显“错台”现象;对比人工钻孔,凿岩机直眼掏槽光面爆破作业可减少人工5人,每循环可节省通风时间0.4 h、节约施工成本约0.157万元,具有较为显著的技术效果和经济价值。

A parallel pilot tunnel with a section size of 6.5 m×6.5 m in a railway tunnel is taken as an example.In view of the practical engineering problems such as the inability of the three-arm rock drill to realize the inclined cut and the long ventilation time after blasting due to the limitation of space in the tunnel,a smooth blasting technology of three-arm rock drill combined with composite straight cut is proposed.Blasting parameters are designed,researched and applied.The results show that the average cycle footage of the blasting scheme can reach 2.8 m to 3.0 m,the hole utilization rate is 93%to 96%,the excavation contour wall is smooth,and there is no obvious′dislocation′phenomenon between the blasting cycles.Compared with manual drilling,the three-arm rock drill combined with the composite straight-hole cutting smooth blasting operation can reduce 5 manual workers,save ventilation time by 0.4 h per cycle,and save about 1,570 yuan in construction cost,which has significant technical effect and economic value.