软弱地层环境下地铁盾构下穿铁路框架桥影响分析及应对措施

Analysis and countermeasures of metro shield tunneling under railway frame bridge in weak stratum

摘要:

以杭州地铁9号线一期工程下穿沪杭铁路框架桥为背景，建立盾构下穿施工三维数值模型，分析软弱地层环境下地铁盾构隧道下穿施工对铁路框架桥的影响，提出多种确保铁路安全运营应对措施，并在施工过程中进行现场监测。数值分析表明，盾构隧道下穿施工中铁路框架桥最大沉降量为6.72 mm，进行洞内注浆加固后，最大沉降量降为4.76 mm，说明在软弱地层环境下及时进行洞内注浆对抑制铁路框架桥的沉降变形具有显著效果；监测结果表明，盾构右线施工对框架桥沉降变形的影响大于左线，铁路框架桥最大沉降达到6.9 mm，采取应对措施及时进行洞内二次注浆，可有效控制框架桥的持续沉降变形，铁路框架桥处于安全可控状态。

Abstract:

Based on the project of Hangzhou Metro Line 9, a three-dimensional numerical model of shield underpass railway frame bridge construction is established. The impact of metro shield tunnel construction through railway frame bridge in weak stratum is analyzed, Multiple countermeasures are proposed to ensure the safe operation of railway, and on-site monitoring is carried out during construction. The research shows that the maximum settlement of the railway frame bridge is 6.72mm. After the grouting reinforcement in the tunnel, the maximum settlement is reduced to 4.76mm, indicating that the timely grouting in the tunnel in the soft stratum has a significant effect on restraining the settlement and deformation in the railway frame bridge construction. The monitoring result shows that the impact of right line construction on the settlement and deformation of the frame bridge is larger than that of the left line, and the maximum settlement of the railway frame bridge reaches 6.9mm. Taking countermeasures and timely carrying out secondary grouting in the tunnel can effectively control the continuous settlement，as well as deformation of the frame bridge，which is in a safe and controllable state.