简介:北京地铁 17 号线区间隧道采用盾构先行通过后横向暗挖风道的施工工艺,上层风道跨越盾构隧道开挖至端墙,下层风道开挖临近至盾构隧道.在上层风道二衬结构保护下,采用倒挂井壁法开挖盾构隧道两侧土体,施工竖井二衬,保留盾构隧道范围内的下层风道侧墙及底板不施工,以保证后期施工安全.通过风道中板预留吊装孔,对管片逐环拆除,然后施工盾构隧道范围内的下层风道侧墙及底板.风道横向暗挖之前,为防止盾构隧道变形,减小地表沉降,需先对风道范围之外的管片采取径向注浆、纵向拉紧、设置环向支撑等加固措施.因需要进行多次受力转换,采用荷载-结构法对二衬结构进行各阶段内力分析.采用地层-结构法对开挖风道、竖井、拆除管片进行各阶段变形及应力分析,结果表明,地表沉降满足要求.监测结果反映地表沉降达到 99.1mm,主要原因为竖井开挖到底后,因遇到承压水,未及时封底,导致支...Abstract:The interval tunnel of Beijing Metro Line 17 adopted the construction technology of a shield first passing through and then transversely excavating the air duct.The upper air duct was excavated across the shield tunnel to the end wall,and the lower air duct was excavated adjacent to the shield tunnel.Under the protection of the secondary lining structure of the upper air duct,the soil on both sides of the shield tunnel was excavated by the inverted shaft wall,the secondary lining of the shaft was constructed,and the side wall and bottom plate of the lower air duct within the scope of the shield tunnel were not constructed to ensure the safety of the later construction.The hoisting holes were reserved throug...
简介:地铁盾构隧道近距离下穿铁路施工时,地层扰动会引起上部既有铁路路基沉降及轨道结构的不平顺,对铁路运营安全产生不利影响.为探讨盾构下穿铁路施工对轨道结构的影响规律,结合某地铁区间盾构隧道下穿胶济铁路施工案例,建立考虑盾构隧道-围岩-路基相互作用的数值模型,分析盾构施工过程中铁路路基沉降及多股轨道的变形特征.结果表明:盾构施工引起路基沉降及轨道变形与铁路之间的距离有关,当盾构施工处于铁路正下方时,路基沉降及轨道的变形最大,且路基的最大沉降为 3.30mm,轨面的最大高低不平顺和最大水平不平顺分别为0.097 5mm和 3.615mm,路基沉降与铁轨变形均处于控制标准范围之内.Abstract:When a subway shield tunnel crosses underneath a railway at a close distance,the strata disturbance will cause the settlement of the upper existing railway subgrade and the irregularity of the track structure,which will adversely affect the safety of railway operation.To explore the influence law of shield tunneling crossing underneath railway construction on track structure,a numerical model considering the interaction of shield tunnel-surrounding rock-subgrade was established in combination with a construction case of a shield tunnel crossing underneath the Qingdao-Jinan Railway in a subway section.The settlement of railway subgrade and the deformation characteristics of multiple tracks during shi...