为提高钻爆法单线铁路隧道仰拱施工质量，改善洞内作业环境，推进装配式结构绿色建造等，以新建川藏铁路色季拉山隧道工程为依托，对装配式仰拱的结构形式，环向、纵向连接，防水，拼装设备，隧底填充，施工工艺及经济性等进行研究。主要研究结论有： 1)仰拱与填充层整体预制成单块空心结构，结构受力条件好，洞内拼装方便； 2)预制块与现浇二次衬砌采用方形榫槽或方形榫槽+预埋钢筋的连接方式，预制块纵向通过张拉精轧螺纹钢进行挤紧，预制块底部采用碎石+回填注浆的垫层进行基底处理。装配式仰拱应用于川藏铁路色季拉山隧道，可实现轨下结构机械化快速施工，有利于提高山岭铁路隧道机械化施工整体水平。

A case study of the SichuanTibet railway′s Shergyla Mountain tunnel is conducted to improve the construction quality of the invert of the singletrack railway tunnel constructed by drilling and blasting method and the environment in the tunnel, as well as promote green construction of the prefabricated structures. Further, the structural form, circumferential and longitudinal connections, waterproofing, assembling equipment, tunnel bottom filling, construction technology, and economic benefits of the prefabricated invert are studied. The main research conclusions are as follows: (1) The invert and the filling layer are integrally prefabricated into a monolithic hollow structure with a good stress condition that is easy to be assembled in the tunnel. (2) The prefabricated block is connected with the castinsitu secondary lining using square tongue and groove or square tongue, groove, and reserved steel. The prefabricated block is longitudinally squeezed by tensioning and finishing rolling rebar, and its underside is treated with crushed stone and backfill groutingcushion. The prefabricated invert is used in the SichuanTibet railway′s Shergyla Mountain tunnel, allowing for rapid and mechanized construction of the undertrack structure, which improves the overall level of mechanized construction of mountain railway tunnels.