地铁车站双层初期支护拱盖法施工过程力学行为研究

Study on the Mechanical Behavior of the the Double-layer Arch Cover Initial Support during the Construction of Subway Stations by Arch-cover Method

拱盖法目前已有较为广泛的推广及应用,现有研究均认识到拱盖是施工的关键,但缺少对施工过程力学行为的深入研究。基于此,以青岛地铁2号线西延段小港站标准段为工程依托,采用数值模拟和现场监测相结合的方法,对“双层初期支护拱盖法”施工过程的力学行为进行研究,重点关注临时竖撑拆除时的力学效应。结果表明:双层拱盖体系充分利用了下层较硬岩土体的承载作用,有效地控制了地表沉降和围岩变形;拆除竖撑前,拱顶压力主要由临时竖撑和第一层拱盖承担,拆除竖撑后,拱顶再次下沉,体系发生应力转换,两层拱盖最终进入协同工作阶段;从最终结果来看,双层拱盖法满足安全施工的要求,已在小港站的施工中得到验证,实现了浅埋大跨度地下结构快速安全施工。

The arch-cover method has been widely promoted and practiced,and extant studies have recognized the arch cover as the key to construction.However,there has been a lack of in-depth research on its mechanical behavior during construction by the arch-cover method.In view of this,based on the standard section of the Xiaogang Station on the west extension of Qingdao Metro Line No.2,this paper studies the mechanical behavior involved in"doublelayer initial support arch-cover method"during construction by combining numerical simulation and field monitoring,with a focus on the mechanical effect when the temporary vertical bracing is removed.The results show that the double-layer arch-cover system makes full use of the bearing effect of the underlying hard rock and soil body to effectively control the ground settlement and surrounding rock deformation;Before the removal of the vertical bracing,the pressure on the arch is mainly borne by the temporary vertical bracing and the first layer of the arch cover;after the removal,the arch sank again,while the system underwent a stress conversion,and the two layers of the arch cover eventually enter a phase of synergistic work.The findings show that the double-layer arch-cover method meets the requirements of safe construction as verified in the construction of the Xiaogang Station,and makes it possible to realize the rapid and safe construction of the shallow large-span underground structure.