山岭隧道机械化大断面法设计关键技术

为解决长大山岭隧道钻爆法机械化安全、快速、高质量施工所面临的技术问题，依托郑万铁路湖北段隧道工程，采用“科研先行、试验验证、推广应用”的工作方法，开展隧道大型机械化修建技术研究与现场试验。结合国内外调研情况及工程实践，得出如下结论： 1)隧道机械化修建方法是对传统方法的系统性改变； 2)Ⅳ、Ⅴ级围岩传统多台阶法、被动支护、围岩压力“分担比”理论与机械化大断面法不相适应； 3)机械化大断面法施工的核心要点是“快挖、快支、主动支、快封闭”； 4)隧道结构设计采用规范中基于松散压力的围岩压力计算方法与实际存在差异，可采用形变压力计算方法； 5)对于采用机械化大断面法施工的隧道，掌子面超前主动支护体系与洞身主动支护体系是确保隧道掌子面附近围岩稳定的关键。

Key Design Technology for Large Cross-Section MechanizedConstruction of Mountainous Tunnels

To realize safe, rapid, and highly efficient mechanized construction of long mountainous railway tunnels using drilling and blasting methods, a case study is conducted on a tunnel project of the Hubei section of the Zhengzhou Wanzhou railway. A working method of "scientific research, test verification, popularization, and application," the exploration research, and field tests of large scale mechanized construction technology of tunnels are performed. According to investigations and engineering practice, some conclusions are drawn as follows: (1) The mechanized construction method of tunnels is a systematic change based on the traditional method. (2) The traditional multibench method, passive support, and surrounding rock pressure sharing in Grades Ⅳ and Ⅴ surrounding rocks are unsuitable for the large cross section mechanized method. (3) The key points of large cross section mechanized construction are fast excavation, fast support, active support, and fast closure. (4) The tunnel structure design adopts the surrounding rock pressure calculation method based on the standard loose pressure, which differs from the actual situation, and can be designed according to the deformation pressure calculation method. (5) For the tunnel constructed by the large cross section mechanized method, the advance active support system of the tunnel face and tunnel body are the keys to the surrounding rock stability near the tunnel face.