双线盾构隧道下穿对既有地铁车站的变形影响

Effects of Deformation on Existing Subway Stations Underneath Two-lane Shield Tunnels

为研究新建双线盾构隧道邻近穿越既有地下建筑引起的一系列变形和破坏问题,以郑州地铁某双线盾构隧道下穿既有车站为背景,采用midas GTS建立三维数值模型,研究双线盾构隧道下穿既有车站施工过程。研究发现:车站底板的竖向沉降曲线随盾构施工过程由“V”形过渡为“W”形,影响范围由3倍隧道直径扩大到5倍,施工引起的既有车站底板变形曲线符合Peck曲线;邻近隧道开挖处支护结构的竖向变形和水平变形整体呈增加趋势,但变形量均小于安全控制标准值。数值模拟结果表明盾构施工期间不需进行额外加固措施,但应对既有车站底板X方向左右各16 m范围内以及C号出入口重点开展监测工作。

To investigate the deformation and failure issues caused by the construction of a new double-line shield tunnel crossing adjacent to existing underground structures,a case study of a double-line shield tunnel beneath an existing station in Zhengzhou′s metro system was conducted.A three-dimensional numerical model was established using midas GTS to examine the construction process of the double-line shield tunnel crossing the existing station.The study found that the vertical settlement curve of the station′s base slab transitioned from a"V"shape to a"W"shape as the shield construction progressed,with the affected zone expanding from three times the tunnel diameter to five times the tunnel diameter.The deformation curve of the base slab induced by the construction matched the Peck curve.The vertical and horizontal deformations of the support structures near the tunnel excavation exhibited an overall increasing trend;however,all deformations remained within the safety control standard limits.The numerical simulation results indicated that no additional reinforcement measures are required during the shield construction period.Nevertheless,monitoring efforts should be focused on a 16 meter area to the left and right of the X direction of the existing station′s base slab,as well as at the C entrance/exit.