大断面黄土隧道弧形导洞法施工关键技术研究

Key Techniques for Arched Heading Excavation of Large-cross-section Loess Tunnels

郑西客运专线黄土隧道总长约52km,涉及多种类型黄土地层,且隧道埋深及含水量变化大,属于极为复杂的大断面黄土隧道群。为保证隧道安全、快速施工,结合现场施工实际和测试结果,对大断面黄土隧道采用弧形导洞法施工的变形特点进行了研究分析。研究结果表明,弧形导洞法不仅适用于不同埋深条件下的砂质及粘土老黄土隧道,而且可用于浅埋非饱和砂质新黄土隧道。文章针对三台阶七步开挖的弧形导洞法提出了核心土、短台阶、大拱脚、快封闭等关键施工技术和施工要点。

On Zhengzhou-Xi＇an passenger dedicated railway there are 52km loess tunnels embedded in various kinds of loesses with overburdens and water content varied in a large extent. In order to ensure safety and rapid construction, deformation characteristics of tunnels during arched heading excavation were studied and analyzed incorporating construction practice and monitoring data. Results indicated that arched heading excavation was not only suitable for sandy and clay old loess tunnels with different overburdens but also suitable for shallow unsaturated sandy new loess tunnels. Author of the paper puts forward core ground, short bench, big arch abutment, quick closure, etc. key techniques for the three-benches-seven-stepes arched heading excavation method.