滨海软土层新建地铁盾构隧道近距离上跨既有地铁隧道修建技术

Construction Techniques of Shield Tunnels Approaching Existing Metro Tunnels in Soft Ground at Seafront Areas

深圳地铁5号线南延工程前湾站-桂湾站盾构区间隧道上跨既有地铁11号线隧道,隧道重叠区域位于滨海淤泥软土地区,附近众多工程群坑关系复杂且相互影响极大。为确保上跨施工时既有地铁11号线隧道不发生超量变形或者破坏,在前桂区间隧道施工前采取了地质补勘、区间土体加固、补充加固、袖阀管注浆加固等施工准备措施,盾构推进过程中综合采用分段施工和参数调整、严格控制盾构推进和管片拼装质量、改良土体、同步注浆和补浆等措施,确保了盾构隧道施工安全可靠。施工监测结果表明,前桂区间盾构施工引起的既有地铁11号线隧道最大位移为5.0 mm,满足地铁保护的安全要求。

The running shield tunnel of Qianwan station-Guiwan station on the southern extension line of Shenzhen Metro Line 5 passes closely over the existing tunnel of Shenzhen Metro Line 11, the overlapped region is located in the soft silt stratum at the seafront, a lot of buildings and underground structures are under construction nearby and they are greatly affected each other. To prevent from over-deformation or failure of the existing tunnel on metro line 11 during the construction of new shield tunnel, some preparation measures like supplementary geological survey, reinforcement of soil mass, additional reinforcement and sleeve valve grouting reinforcement were adopted before construction of the Qianwan-Guiwan running tunnel, and sectional construction, parameter adjustment, strict control of shield driving, quality management of segment erection, conditioning of soil mass, simultaneous grouting and compensation grouting were taken to ensure safe shield construction. The construction monitoring results show that the maximum tunnel displacement of metro line 11 induced by the shield construction of Qianwan-Guiwan running tunnel is 5.0 mm, meeting the safety requirements of metro protection.