盾构隧道埋深对临近铁路桥梁的影响分析

为研究盾构隧道下穿临近铁路桥梁过程中隧道埋深对既有桥梁沉降变形及水平位移变化的影响，以武汉地铁3号线区间盾构穿越铁路桥梁工程为依托，利用有限元软件ANSYS对不同隧道埋深（2D、2.5D、3D（D为隧道直径））下桥梁的梁体结构、轨道线路及桩基位移等进行对比分析，并结合现场数据进行验证。研究结果表明： 1）随着隧道埋深的增大会引起桩基、梁体及钢轨等结构竖向位移的增大，当隧道埋深为18 m时，墩台最大沉降超过了限制值； 2）隧道埋深分别为12、15、18 m时，桥梁墩台及梁体结构均表现出以沉降为主的变形，而水平位移变化幅度较小； 3）在满足地表沉降限值的条件下可适当减少隧道埋深，以控制隧道开挖引起的上部桥梁、钢轨等结构物变形。

Analysis on Influence of Shield Tunnel Buried Depth on Adjacent Railway Bridges

Taking the construction of the shield tunnel crossing railway bridge of Wuhan Metro Line 3 as an example, the displacement of the beam structure, track line and pile bridges under different burial depths (2D, 2.5D, 3D) are analyzed with the finite element software ANSYS and then being validated with the field data to study the effect of tunnel buried depth on the settlement deformation and horizontal displacement of existing bridges during the process of shield tunnels passing through adjacent railway bridges. The results showed that: (1) Increasing the depth of tunnel will increase the vertical displacement of pile foundation, beam and rail structure, and when the depth of the tunnel is 18 m, the maximum settlement of the pier exceeds the limit value; (2) When the tunnel burial depths are 12 m, 15 m and 18 m, the deformations of piers and beam structures are mainly vertical displacements, while horizontal displacements are smaller; (3) When the surface subsidence limit is met, the deformation of the upper bridges, rails, and other structures caused by the tunnel excavation is controlled by appropriately reducing the tunnel burial depth.