地铁双区间下穿既有盾构隧道结构变形控制措施及效果分析

Structural deformation control measures and effect analysis of subway double-section underpassing existing shield tunnel

为解决城市地铁隧道极小间距下穿上方构筑物结构变形控制的工程难题,剖析了下穿工程风险特点并设定初步变形控制策略,通过精细化数值模拟研究地铁双区间下穿既有盾构隧道结构变形预测和控制效果。着重分析下穿工程段的关键风险和影响区域,基于现场监测数据验证了超前支护、优化开挖方法及盾构结构加强的联合控制措施的可行性。研究结果表明,地铁双区间中心截面周边±30m是控制施工扰动和盾构结构变形的重点区域,超前管棚具有纵向梁承载作用,深孔注浆具有横向拱承载作用,两者协同承载实现了较好的地层变形控制效果,使盾构结构变形控制在5.0mm以内,可为类似工程提供参考。

In order to solve the engineering problem of the structural deformation control of the urban subway tunnel underpassing the upper structure with extremely small spacing,the risk characteristics of the underpassing engineering were analyzed and a preliminary deformation control strategy was set up,and the structural deformation prediction and control effects of existing shield tunnel under the subway double-section was studied through refined numerical simulation.Focusing on the analysis of the key risks and affected areas of the underpassing engineering section,the feasibility of the joint control measures of advanced support,optimized excavation method and shield structure reinforcement was verified based on on-site monitoring data.The research results show that the±30m area around the central section of the subway double-section is the key area to control construction disturbance and shield structure deformation.The advanced pipe shed has the bearing function of the longitudinal beam,and the deep hole grouting has the bearing function of the transverse arch.The joint bearing of the two has achieved a better effect of controlling the deformation of the ground,and the deformation of the shield structure is controlled within 5.0mm,which can provide reference for similar engineering.