It leads to many disasters in the construclion of in-building soil tunnels that the design and construction methods of the current soil tunnel are immature. Using in-building "Tianhengshan" soil tunnel as an engineering background, according to the characteristics of large cross-section shallow soil tunnel in cold regions, and on the basis of the improvement and innovation for "the construction method with three steps and seven paces", "the construction method with two steps and five paces" is raised here which is suited for shallow soil tunnels, thereby passing through "Tianhengshan" clay strata of soft plastic state safely, economically and fast. The dynamic displacement monitoring results from following the tracks of construction indicate that "the construction method with two steps and five paces" adopted in large cross-section shallow soil tunnels could make the deformation of surrounding rocks a little, meet the needs of the deformation standard for soil tunnel, and ensure the construction safety of the tunnel.%当前土质隧道的设计、施工方法很不成熟,导致在建土质隧道施工灾害频发.以在建的天恒山土质隧道为工程背景,针对严寒地区大断面浅埋土质隧道的特点,在改进并革新"三台阶七步"施工法基础上提出了适用于浅埋土质隧道的"两台阶五步"施工法,安全、经济、快速地穿越了天恒山软可塑状态的亚粘土地层.论文详细介绍了"两台阶五步"施工法的技术要点和现场实施过程;并跟踪施工进行的动态位移监测,结果表明,大断面浅埋土质隧道采用"两台阶五步施工工法",围岩变形量小,满足土质隧道变形规范要求.
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