盾构近距离下穿桥梁数值模拟与监测分析

Numerical Simulation and Monitoring Analysis of Shield Tunneling through Bridge in Short Distance

摘要:

利用三维有限元数值模型，模拟计算盾构隧道穿桥引起的桥桩位移、内力和表面沉降，通过盾构隧道穿越桥梁基础的现场监测，将监测数据与数值计算结果进行对比分析，最终得出杭州机场轨道快线盾构下穿高速某枢纽桥梁桩基引起的桥桩位移、内力变化和地表沉降规律。数值模拟计算结果表明，盾构隧道开挖过程中对桩身的轴力影响较大；桥梁桩的弯矩也有类似的变化趋势；桥梁桩的水平位移随着埋深的增大而减小；不论是水平位移和竖向沉降，均是先开工的右线隧道对其影响较大；数值模拟计算结果与监测数据基本一致。桥桩沉降最大差值为0.9 mm，地表沉降最大差值为0.4 mm。沉降小于施工要求控制的12 mm。模拟计算中选取的参数与模型和实际情况吻合较好，对杭州地区类似工程具有一定的参考价值，施工前应有相应措施和预案保证地层稳定和建构筑物的安全。

Abstract:

A 3D finite element numerical model is used to simulate and calculate the displacement， internal force， and surface settlement of bridge piles caused by shield tunneling through the bridge. By the on-site monitoring of shield tunneling through bridge foundation， the monitoring data and the numerical calculation results are compared and analyzed. The displacement， internal force change and surface settlement law of bridge piles caused by the shield tunneling through a hub bridge pile foundation of Hangzhou Airport Rail Express are finally obtained. The numerical simulation calculation results indicate that the influence on the axial force of the pile body is significant during the excavation process of the shield tunnel. The bending moment of bridge piles shows a similar change trend. The horizontal displacement of bridge piles is reduced with the increase of burial depth. Both horizontal displacement and vertical settlement are greatly influenced by the right-side tunnel which is constructed first. The numerical simulation calculating results are basically consistent with the monitoring data. The maximum difference value of pile settlement is 0.9 mm， and the maximum different value of surface settlement is 0.4 mm. The settlement is less than 12 mm that is required to control in the construction. The parameters selected in the simulation calculation are in good agreement with the model and the actual situations， which has certain reference value for similar projects in the area of Hangzhou. Before construction， the corresponding measures and predetermined schemes should be taken to ensure the stability of strata and the safety of structures.