蒙华铁路中条山隧道施工关键技术

Key Construction Technologies for Zhongtiaoshan Tunnel on Menghua Railway

针对蒙华铁路中条山隧道在施工过程中遇到的围岩软弱易风化、仰拱开挖后基底承载力不足、斜井砂砾层承压富水和隧道涌水量大等问题,介绍施工过程中所采用的软弱围岩微台阶带仰拱一次开挖快速封闭成环、铁路单线隧道二次衬砌仰拱及仰拱填充大区段、碎石换填基底加固并在基底埋设排水管以及分段截流、反坡排水等关键施工技术。主要研究结论如下:1)仰拱与下台阶一次爆破成型,减少了爆破围岩的二次扰动,能有效控制周边收敛和拱顶沉降;2)采用24 m单线隧道全液压履带式栈桥,有效减少了仰拱之间施工缝隙对接次数,提高了仰拱的整体性;3)对有水软岩地段采用碎石换填并注浆加固,起到了良好的堵水效果;4)采取分段截流,减少了反坡施工掌子面的排水量,加快了掌子面的施工进度。

During the construction of Zhongtiaoshan Tunnel on Menghua Railway,a series of problems,i. e. soft and weak and weathered surrounding rock,inadequate bearing capacity of inverted arch base,rich water of sandy-cobble load bearing strata of inclined shaft and large volume of water inrush of tunnel,were encountered. Key technologies,i. e. rapid closed ring by micro-bench of soft and weak surrounding rock with one-time inverted arch excavation,largesection filling of inverted arch of secondary lining and inverted arch of single-line railway tunnel,spall filling and reinforcement of inverted arch base and drainage pipe set in inverted arch base( including sectioned water stop and reverse-slope drainage technology), are introduced. Some conclusions are drawn as follows: 1) The secondary disturbance of surrounding rock can be reduced and the surrounding convergence and crown top settlement can be effectively controlled by one-time blasting and shaped of inverted arch and lower bench. 2) The connecting time of construction joints between inverted arches can be reduced and the integrity of inverted arch can be improved by 24 mlong hydraulic crawler-type trestle. 3) The water stop effect of water-contained soft rock section can be improved by spall filling and grouting reinforcement. 4) The water drainage volume of reserve slope-face excavation can be reduced and the construction schedule of excavation face can be shortened by sectioned water stopping technology.