定临高速黑庄坪隧道施工技术

Construction Technology of Heizhuangping Tunnel in Dinglin Expressway

黑庄坪隧道施工时,棕红色泥质结构的砂岩遇水易软化、失水易龟裂的性质使得隧道的掘进难度颇大.施工现场决定用出口悬臂掘进,入口钻爆掘进的并辅以机械开挖组合开掘技术进行施工.针对黑庄坪隧道的围岩级别提出了相应的爆破方案,并对悬臂掘进法超欠挖的影响因素进行了分析.通过现场监测统计,得到了钻爆法和悬臂掘进法不同断面的超欠挖值.实践表明,悬臂掘进月平均超欠挖量为7~10 cm,而钻爆法月超欠挖为19~22 cm,比悬臂掘进法的两倍还多,可见悬臂掘进法可以更好地控制超欠挖量.

During the construction of Heizhuang Ping tunnel,the brownish red mud sandstone is easy to soften and crack when water is lost,which makes the tunneling difficult.To use cantilever excavation at the exit is decided,the drilling and blasting of the entrance is combined with mechanical excavation technology for construction.According to the surrounding rock level of Heizhuang Ping tunnel,the corresponding blasting scheme is put forward,and the influence factors of over under-excavation by cantilever tunneling method are analyzed.Through field monitoring statistics,the over-under-excavation values of different sections of drilling and blasting method and cantilever tunneling method are obtained.The practice shows that the average monthly over under-excavation amount of cantilever tunneling is 7~10 cm,while the monthly over-under-excavation amount of drilling and blasting method is 19~22 cm,which is more than twice of the cantilever tunneling method.It can be seen that the cantilever tunneling method can better control the over under-excavation amount.