新建市政桥梁施工对既有隧道变形控制及安全性研究

Study on Deformation Control and Safety of Existing Tunnels in Construction of New Municipal Bridges

摘要:

采用数值模拟方法，定量评估桥梁施工对下伏地铁盾构隧道稳定性的影响。通过系统分析桥梁建设全过程（开挖成孔、桥墩桩基施工、回填及路面施工）中隧道的多维度结构响应，揭示了隧道在轴向、横向、垂向位移及断面收敛变形等方面的演化规律。结果表明：隧道位移与施工工序呈时序耦合关系，各向位移均在主路施工阶段达到峰值，其中垂向沉降（-0.32 mm）与径向收敛（0.27 mm）最为显著，是该阶段成为控制安全的最不利工况。位移发展主要受荷载施加与土体应力路径控制，初期卸荷引起轻微回弹，后续加载导致持续沉降与收敛，变形累积效应明显。模拟结果均远低于规范限值，结构安全裕度充足，验证了施工方案的可行性，相关方法与结论可为类似邻近工程的风险评估与防控提供依据。

Abstract:

The numerical simulation methods are used to quantitatively evaluate the impact of bridge construction on the stability of the underlying subway shield tunnel. By systematically analyzing the multidimensional structural response of the tunnel throughout the bridge construction process such as excavation and tunneling, pile foundation construction, backfilling and pavement construction, the evolution patterns of tunnel axial, lateral and vertical displacements, as well as cross-sectional convergence deformation are revealed. The result shows that the displacements of the tunnels demonstrate a sequential coupling relationship with various construction phases, and all displacements reach their peak during the main road construction, in which the vertical settlement (-0.32 mm) and the radial convergence (0.27 mm) are the most pronounced, and are this stage that becomes the most unfavorable condition for controlling safety. The development of displacement is principally governed by the application of load and the control of soil stress paths. The accumulative effect of deformation is obvious because of minor rebound caused by the initial unloading and the continuous settlement and convergence led by the subsequent loading. The simulation results are all lower than the limits specified in the code. The structural safety margin is sufficient, verifying the feasibility of the construction scheme. The related methods and conclusions can provide a basis for risk assessment and control in similar adjacent projects.