中等断面隧道长进尺直孔掏槽爆破开挖与超欠挖控制现场试验  

Field Test of Long Footage Burn Cut Blasting Excavation and Control of Overcut and Undercut in Medium Section Tunnel

作　　者：龚伟毅 姚颖康 杜宇翔 GONG Wei-yi;YAO Ying-kang;DU Yu-xiang(The 1st Engineeing Co.,Ltd.of China Railway 12 th Bureau Group,Xi'an 710038,China;State Key Laboratory of Precision Blasting,Jianghan University,Wuhan 430056,China;Hubei Key Laboratory of Blasting Engineering,Jianghan University,Wuhan 430056,China)

机构地区：[1]中铁十二局集团第一工程有限公司,西安710038 [2]江汉大学精细爆破国家重点实验室,武汉430056 [3]江汉大学湖北(武汉)爆炸与爆破技术研究院,武汉430056

出　　处：《爆破》2024年第2期32-39,共8页Blasting

基　　金：湖北省教育厅科学研究计划指导性项目(B2022282)。

摘　　要：中等断面隧道受施工范围限制易导致爆破难度大,循环进尺短,超欠挖问题严重,长进尺开挖和超欠挖控制是降本增效的有效途径。基于某中等断面隧道工程设计了长进尺直孔掏槽爆破方案,进行了40个循环的爆破开挖现场试验,结果表明:(1)按照爆破手册设计中等断面隧道开挖爆破参数,往往大块率高,掌子面不平整,适当增加直孔掏槽孔单孔装药量(现场试验掏槽药量占比由12.8%增至18.1%),可获得较好的爆破效果;(2)在初步设计参数基础上调整了中等断面隧道周边孔单孔装药量,线装药密度最终确定为0.27 kg/m,轮廓成形效果好,半孔率达90%以上,现场40个爆破循环超挖平均值为18.6 cm,分析可知超挖量主要由轮廓线处留置错台造成,在超挖控制方面,除了周边孔参数的合理设计外,应在钻孔施工过程中尽可能减小错台宽度,从而降低超挖;(3)直孔掏槽方案能很好地匹配凿岩台车钻孔施工,实现机械化长进尺爆破开挖,但超欠挖精细控制和爆破施工成本控制是重难点问题,需从钻孔人员操作技术和现场施工管理模式方面进行优化提升。研究成果可为中等断面隧道机械化钻爆施工、长进尺爆破开挖与超欠挖精细控制设计和施工提供参考依据。Due to the limitations in construction scope,blasting a medium-section tunnel is challenging as it often results in short circular footage and significant over and under excavation.To reduce costs and increase efficiency,it is essential to focus on long footage excavation and fine control of over and under excavation.In this study,a straight hole cutting blasting scheme was designed for a medium section tunnel project and 40 cycles of blasting excavation field tests were conducted.The results revealed that when designing the long footage blasting parameters for a medium section tunnel based on the blasting design manual,issues such as high block rate and uneven face frequently arise.However,by appropriately increasing the charge of the cut part(the proportion of charge of the cut part increased from 12.8%to 18.1%in our field test),better blasting effects were achieved.Additionally,by reducing the charge amount of peripheral holes and adjusting their distance from each other,smooth blasting effect was effectively ensured.During the field test,adjustments were made to the charge amount of peripheral holes based on preliminary design for blasting parameters.This resulted in good contour forming effects with a half-hole rate exceeding 90%.However,an average overcutting value of 18.6 cm was observed across all 40 excavation sections during the blasting cycle.The main cause for this overcutting was identified as platform irregularities along the contour line.To address this issue,it is necessary not only to reduce external drilling angles but also control platform width alongside reasonable parameter designs for surrounding holes.The straight hole cutting scheme proved compatible with three-arm rock drilling truck construction methods while enabling mechanized long-shot blasting excavations.Nevertheless,precise control over overcutting and undercutting remains challenging along with cost management during blast construction.It is necessary to optimize and improve the operation technology of drilling personnel and the m

关 键 词：中等断面隧道 直孔掏槽 长进尺开挖 超欠挖控制 精细爆破 

分 类 号：TU375.1[建筑科学—结构工程]