超浅覆土工况下类矩形盾构法在宁波轨道交通4号线出入段线施工中的应用

Application of Quasi-rectangular Shield Tunneling in Ningbo Rail Transit Line 4 Access Line Construction under Ultra-shallow Covering Soil Working Condition

类矩形盾构法因其具有对周边环境影响小、空间利用率高等优势,已在宁波轨道交通中多次应用。该施工方法在出入段线的施工中效果尤为显著。依托宁波轨道交通4号线东钱湖车辆段出入段线施工项目,提出了超浅覆土工况下类矩形盾构隧道的设计及施工方案。对原设计方案及2个施工优化方案进行对比,方案二(417 m类矩形盾构掘进+其余区段明挖)在技术性及经济性上均具有显著优势。为了确保方案二的盾构施工安全及隧道永久抗浮,采取了抗浮板技术。现场施工监测数据表明:抗浮板在超浅覆土工况下类矩形盾构隧道掘进过程中的抗浮控制效果显著。

Quasi-rectangular shield tunneling method features less environmental impact and higher space utilization rate,and has been applied in Ningbo Rail Transit for many times,having particularly obvious effect in the access line construction.Based on the access line project of Dongqianhu Vehicle Depot of Ningbo Rail Transit Line 4,the design and construction scheme of quasi-rectangular shield tunneling under ultra-shallow covering soil working condition is proposed.With a comparison of the original design scheme and 2 construction optimization schemes,it is evident that the scheme 2(417 m quasi-rectangular shield tunneling+open excavation in other sections)has significant advantages in terms of technical economy,in which the anti-buoyancy board technology is adopted to ensure the safety of shield construction and permanent anti-buoyancy of the tunnel.The on-site construction monitoring data shows that the anti-buoyancy control effect brought by anti-buoyancy board is significant during the excavation of the quasi-rectangular shield tunneling under ultra-shallow covering soil working condition.