高原铁路TBM预备洞浅埋软硬不均频变地层开挖与爆破关键技术

以某高原铁路隧道左右线进口2台开敞式TBM预备洞为例，针对钻爆法施工中所遇到的富水浅埋、软硬不均且频变的Ⅵ、Ⅴ、Ⅳ级围岩地层，以“岩变我变，主动应对，减震防坍”为原则，分别采取变换台阶高度动态光面爆破关键技术、三台阶预留核心土环形导坑松动爆破技术、爆破先掏槽与液压破碎锤后扩修边技术、悬臂掘进机（铣挖机）开挖上台阶与下台阶松动爆破技术、液压破碎锤开挖上台阶与反装松土器扩修边及拱脚弱爆破等开挖与爆破关键技术。采取了开挖与爆破关键技术后，施工安全、快速，顺利完成了预备洞施工。

Key Techniques of Excavation and Blasting in Shallow Buried Soft and HardStrata of Tunnel Boring Machine Preparatory Tunnel of Plateau Railway

Two open tunnel boring machines bored the left and right line preparatory tunnels of a tunnel of the advanced bid double tunnel and one bridge project. During the drill and blast construction, water rich Grades Ⅳ, Ⅴ, and Ⅵ surrounding rocks with soft and hard soils were encountered. As a result, the principle technology varies with lithology, active treatment, and vibration reduction is adopted. Furthermore, techniques such as bench change and automatic blasting, three bench reserved core soil and annular pilot tunnel loose blasting, cutting before blasting and edge cutting by hydraulic top heading milling excavation and lower bench loose blasting, top heading hydraulic hammer excavation and edge cutting by scarifier, and arch foot weak blasting are employed, resulting in successful completion of preparatory tunnels.