大直径中空直眼掏槽技术在隧道救援中的应用

Application of Parallel Cut Blasting with Large Empty Hole in Tunnel Rescue

岳家沟隧道工程在里程号RK75+470处突发塌方,为了营救右洞掌子面处的3名被困施工人员,采用钻爆法开挖横洞的救援方案,即从隧道左洞开挖小断面横洞到右洞的掌子面,形成新的救生通道。根据理论计算,设计了大直径中空直眼掏槽爆破方案:空孔直径为152 mm,空孔每次钻进10 m,围绕空孔共有2圈掏槽孔,第一圈掏槽孔与第二圈掏槽孔各有4个孔,孔径均为42 mm,孔深均为5 m,第一圈掏槽孔为竖向正方形布置,距空孔中心为200 mm,第二圈掏槽孔为水平向正方形布置,与第一圈掏槽孔孔间连线的垂距为340 mm。结果表明:大直径空孔为后续炮孔爆破提供了足够大的自由面,平均循环进尺4. 3 m,掘进效率得到显著提高,3名被困施工人员成功获救。采用该技术,减少了钻孔数量,减少了钻孔时间,减少了循环次数,加快了掘进速度,节约了火工品的消耗。

A collapse accident occurred at RK75+470 of Yuejiagou tunnel.In order to rescue three constructors who were trapped in the face of the right tunnel,rescue plan of excavating a transverse tunnel by means of drilling and blasting method was adopted.That is excavating a transverse gallery with a small cross section from the left tun- nel to the face of the right tunnel.Then a new emergency exits can ba found.Based on the theoretical calculation, scheme of parallel cut blasting with large empty hole was designed.Diameter of the empty hole is 152mm.Depth of the empty hole is 10m each drilling.There are two laps cutting holes around the central empty hole.Each has four cutting holes of the first lap and the second lap.Diameter of all these cutting holes is 42mm.Depth of all these cutting holes is 5m.Layout of the first lap cutting holes is vertical square.Distance between the first lap cutting holes and the empty hole is 200mm.Layout of the second lap cutting holes is horizontal square.Vertical distance between the second lap cutting holes and the connected line of the first lap cutting holes is 340mm.Results showed that large empty hole provides sufficient free face for the subsequent blast holes.Average footage cycle was 4.3m.Drivage efficiency was significantly improved.Three trapped constructors were successful rescued.By means of this method, number of drilling holes,drilling time and cycle number were reduced,drivage speed was enhanced,consumption of initiating explosive device was saved.