大直径泥水盾构始发钢套筒的防扭施工技术——以孟加拉卡纳普里河水下隧道为例

为更好地控制超大直径泥水平衡盾构始发阶段的施工风险，依托“一带一路”孟中印缅经济走廊大型基础设施项目孟加拉卡纳普里河水下隧道，采用开挖直径12.16 m超大型气垫式泥水加压平衡盾构密闭始发钢套筒进行始发。为解决当地吊装资源和远洋航运的限制，钢套筒采用分片设计。盾构在套筒内破除洞门围护结构前，须严格控制盾构掘进转矩，避免盾体及钢套筒整体扭转。对钢套筒始发整体扭转进行分析，并运用有限元仿真技术分析始发施工中的盾构钢套筒抗扭性能。研究结果表明： 钢套筒可以满足始发前后所需的抵抗转矩，最大应力为16.6 MPa，最大位移为0.52 mm，最大水平位移为0.02 mm，最大竖向位移为0.51 mm，满足盾构始发钢套筒的受力和变形验算条件。基于仿真计算结果，制定对应的超大直径盾构始发钢套筒的抗扭措施。

Torsion resistant Construction Technology for Steel SleeveUsed in Launching of Large diameter Slurry Shield:  a Case Study of Canapuri River Tunnel in Bangladesh

The construction risks in the launching stage of super large slurry balance shield should be controlled. As a result, the steel sleeve used in launching of a super large air cushion slurry pressure balance shield with a diameter of 12.16 m of the Canapuri River Tunnel Project in Bangladesh of Bangladesh China India Myanmar Economic Corridor of "the Belt and Road" is designed in sections considering the local hoisting resources and the limitation of ocean shipping. Before the shield breaks the retaining structure behind the tunnel portal in the sleeve, it is necessary to strictly control the driving torque of the shield to avoid the whole torsion of the shield body and the steel sleeve. The torsional resistance of the steel sleeve of the shield during the launching construction is analyzed by using finite element simulation technology. The results show that: (1) The steel sleeve can meet the resistance torque required for shield launching. (2) The maximum stress of the steel sleeve, the maximum displacement, the maximum horizontal displacement and the maximum vertical displacement are 16.6 MPa, 0.52 mm, 0.02 mm and 0.51 mm, respectively, which satisfies the checking conditions of the stress and deformation of the initial steel sleeve of shield tunneling. The corresponding anti torsion measures for steel sleeve launching of super large diameter shield are formulated based on the simulation results.