大断面隧道轮廓控制爆破技术研究与应用

预留光面爆破层全断面一次爆破技术和导爆索三角形搭接起爆周边孔技术是控制大断面隧道轮廓成形效果的有效手段。介绍并对比研究了这2种爆破模式，给出相应的工程应用条件；分析了预留光面爆破层全断面一次爆破技术优势，给出预留光爆层爆破参数计算公式；分析了导爆索三角形搭接传爆机制，对传爆时间进行理论计算，结果显示该搭接方式可以在5 ms内将起爆信号传至整个爆破网路、相邻炮孔最大起爆时差小于1 ms。以东天山隧道工程为背景，对2种爆破模式进行现场试验，结果表明2种模式均可有效控制开挖断面轮廓，提高炮孔痕迹率，降低超挖量。2种模式的适用条件分别为：Ⅳ级围岩较好情况下及Ⅲ级围岩以上可应用预留光面爆破层全断面一次爆破技术，Ⅳ级围岩较差情况下乃至Ⅴ级围岩可应用导爆索三角形搭接起爆周边孔技术。

Study and Application of Contour Control Blasting Technology for Large Section Tunnel

With the general trend of tunnel construction in China towards large and super-large sections，the application of full-face blasting excavation method in tunnel excavation generally has the problems of poor contour forming effect，low trace rate of blasting holes and large under or over excavation.The technology of full section blasting with pre-arranged layer and the technology of detonating peripheral hole with triangular lap of detonating cord can effectively solve the above problems and achieve good contour forming effect.The two kinds of blasting modes are introduced and compared，and the corresponding engineering application conditions are given in this paper.The advantages of the full section blasting technology with pre-arranged layer are analyzed，and the calculation formula for the parameters of the pre-arranged layer is given.The detonating mechanism of triangular lap of detonating cord is analyzed.The theoretical calculation of the blasting time is calculated，and as a result,the detonation signal can be transmitted to the whole blasting network in 5 ms，and the maximum detonating time difference between adjacent blast hole is less than 1ms.Based on the Dong Tianshan tunnel project，the field tests of two kinds of blasting modes have been carried out.The results show that both modes can effectively control the contour of the excavation section，improve the hole trace rate and reduce the over excavation.The applicable conditions of the two modes are as follows：The technology of full section blasting with pre-arranged layer can be used under the good condition of Ⅳ class surrounding rock and above grade Ⅲ surrounding rock；The technology of detonating peripheral hole with triangular lap of detonating cord can be applied under the poor condition of Ⅳ class surrounding rock and Ⅴ surrounding rock.The results can provide reference for similar projects.