复杂条件下超大跨地铁车站施工仿真技术研究

研究目的：研究复杂条件下超大跨浅埋暗挖地铁车站施工时,不同施工工序下开挖引起的地层扰动对地表沉降及拱顶下沉的影响规律。研究方法：以某超大跨浅埋暗挖地铁车站作为工程背景,利用ANSYS有限元软件作为开发平台,以浅埋暗挖隧道开挖支护理论为基础,采用平面应变模式,对双层两柱暗挖结构的三跨连拱隧道开挖支护全过程进行非线性仿真研究。研究结果：仿真计算结果与现场监测数据基本吻合,可以指导该类型隧道施工的地层沉降仿真研究、施工作业及信息化施工。研究结论：地表沉降影响范围约3倍洞径,最大沉降量为20.75 mm,拱顶最大下沉量为29.93 mm;超大跨隧道分部开挖“群洞效应”明显,在“上软下硬”围岩地层中,地层变形控制的关键工序是上部软岩断面的开挖支护,下部断面要减少爆破振动对地层变形的影响;大跨隧道开挖支护中,不同分部开挖引起的沉降量及沉降槽宽度是不同的。

Research on Emulation Technology for Construction of Super Long-span Metro Station Under Complex Conditions

Research purposes: The researches are done on the influence regularities on surface and crown settlements by stratum disturbance caused by the excavation with different construction procedures when construction of super long-span metro station under complex conditions with shallow burying and surface excavation method.Research methods:Taking construction of one metro station with shallow burying and surface excavation method as an example,the researches are done on the non-linear emulation of entire excavation and support processes for tri-span arch tunnel with double deck and pillar surface excavation structure by using ANSYS finite-element software as platform and adopting plane strain mode based on the theory of excavation and support for shallow burying tunnel.Research results:The results of emulation calculation are basically correspondent to the site monitored data,so it can be used for instructing emulation research on stratum settlement and construction of similar tunnel.Research conclusions:The influencing range on surface subsidence is about three times than the tunnel diameter,the max.settlement amount is 20.75 mm and the max.crown settlement is 29.93 mm.For excavation of super long-span shallow burying tunnel,the " group caves effect" is obvious and the control of surface crown settlements is key procedure with the support in the upper section in wall rock stratum with soft top and weak bottom.The blasting shock should be reduced for the lower section for controlling distortion.The settlement and subsidence values are different for excavation in different areas in the process of excavation and support of super long-span tunnel.