小间距隧道钻爆施工开挖工序研究

采用钻爆法修建小间距隧道时,后行隧道爆破施工将对先行隧道结构产生振动,影响先行隧道的安全性。以北京怀柔区头道穴小间距隧道为工程背景,采用ANSYS软件建立二维数值计算模型,并结合现场监测数据完善计算模型,研究了4种不同施工工序时后行隧道对先行隧道结构产生的振动影响,得出先行隧道迎爆侧边墙受到的振动最大,拱脚处和轮廓线不连续处出现应力集中;因此规定施工中最大段药量不能超过32kg,且先行隧道的下台阶开挖掌子面不宜超越后行隧道上台阶掌子面。若有进度要求,先行隧道宜先开挖左下台阶,以达到保护先行隧道安全的目的。

The research of the process of drilling and blasting of small spacing tunnel

When small spacing tunnel is built using drilling and blasting,blasting vibration from next built tunnel affects the safety of first built tunnel.Based on Toudaoxue small spacing tunnel in Huairou district of Beijing,the finite element model of actual engineering is modeled by ANSYS software.The finite element model is updated by the monitoring data.According to the finite element model,blasting vibration of first built tunnel is analyzed when four different excavation procedures.It is con-cluded that the vibration of the side wall of the first built tunnel is the largest,the stress concentration occurs at the foot of the tunnel and the discontinuity of the contour line.It is advised that the maximum charge per delay is less than 32 kg and the face of lower bench of preceding tunnel should not be beyond the tunnel face of backward tunnel.The part of the lower left bench can be excavated in order to reduce the time limit for the tunnel.