高原多年冻土隧道施工技术及方案研究

Research on Construction Technology and Plans of Tunnels in the Plateau Permafrost Region

青藏铁路格尔木至拉萨段昆仑山隧道和风火山隧道位于青藏高原海拔4 500 m以上的多年冻土区,是目前世界上在高原多年冻土区这一特殊气候及围岩条件下修建的最高海拔的隧道工程。在高寒缺氧的高原环境下,隧道施工中保护冻土以及隧道的支护是本工程的技术难点。本文通过对高原多年冻土隧道施工方案及施工技术的实践研究,提出在施工过程中为保持洞内气温而采用两种送风方式:加温预热通风系统和普通通风系统,以及昆仑山隧道采用的背负式供氧技术、风火山隧道采用的洞内弥漫式施工供氧技术的方案,并且介绍了湿喷混凝土支护和模筑衬砌混凝土施工技术以及防水隔热层施工的关键施工工艺,给出了施工过程中的各项工程技术指标,对同类隧道施工具有借鉴作用。

The Kunlunshan Tunnel and Fenghuoshan Tunnel in the Gela Section of the Qinghai-Tibet Railway lie in the permafrost area of the Qinghai-Tibet plateau at an elevation of more than 4500m. Up to now they remain the highest tunnels built in such surrounding rock and special climate in the plateau permafrost area in the world. The difficult point of technology is to preserve the frozen soil and protect the tunnel support during construction under the cold and oxygen-deficient environment. In this paper, through reseach on construction plans and technologies in practices, two modes of tunnel ventilation are presented, one being the preheating ventilation systerm and the other being the common ventilation systerm together with the shouldered type oxygensupply adopted in the Kunlunshan Tunnel and the diffusion-type oxygen-supply adopted in the Fenghuoshan Tunnel. Wet-shotcrete supporting, tunnel lining and construction of waterproof heatqnsulation layers are introduced. Engineering indexes are also provided. The research results have reference value to construction of similar tunnels.