软土地层小净距叠交盾构隧道施工方案研究

Study on Construction Scheme of Overlapped Shield Tunnel with Small Clear Spacing in Soft Soil Layer

以无锡地铁3号线出入段隧道上穿地铁3号线长江路站—机场站区间隧道及既有电力隧道为工程背景,利用FLAC 3D 5. 0软件进行数值计算,对比分析不同施工顺序的地表沉降及隧道结构竖向变形。分析结果表明:先开挖下部长机区间隧道后开挖上部出入段隧道地表最大沉降为9. 33 mm,隧道结构最大竖向变形为23. 0 mm;先开挖上部出入段隧道后开挖下部长机区间隧道地表最大沉降为13. 10 mm,隧道结构最大竖向变形为33. 8 mm。建议采用先下后上的顺序施工,叠交段施工时应保持土仓压力稳定,严格控制同步注浆压力及注浆量,必要时可在下部隧道施工后设置临时支撑,并做好监控量测。

Taking the tunnel of entry and exit section in Wuxi Metro Line 3 passing through the tunnel between Changjiang Road Station and Airport Station in Metro Line 3 and the existing electric power tunnel as the engineering background,the surface subsidence and vertical deformation of tunnel structure in different construction sequence were compared and analyzed by using FLAC 3D 5.0 software to carry out numerical calculation.The results show that the maximum surface subsidence is 9.33 mm and the maximum vertical deformation of the tunnel structure is 23.0 mm when the upper entry and exit section tunnel was excavated after the excavation of lower Changjiang Road Station to Airport Station interval tunnel,while the maximum surface subsidence is 13.10 mm and the maximum vertical deformation of the tunnel structure is 33.8 mm when lower Changjiang Road Station to Airport Station interval tunnel was excavated after the excavation of the upper entry and exit section tunnel.It is recommended that the construction sequence of the lower part before the upper part should be adopted,the pressure of the soil warehouse should be stable during the construction of overlapped sections,synchronous grouting pressure and grouting volume should be controlled strictly,temporary support should be installed after the construction of the lower tunnel,and monitoring and measuring should be done if it is necessary.