盾构始发与接收对工作井围护结构的影响研究

Influence of Shield Launching and Receiving on Working Shaft Retaining Structure

[目的]一般情况下,盾构机均在盾构工作井主体结构施工完成后才进行始发或接收,由于诸多因素的限制,往往需要考虑盾构工作井主体结构尚未施工时进行盾构始发或接收的情况,因此需研究盾构始发与接收对盾构工作井围护结构的影响。[方法]以成都地铁某标准地下三层岛式车站为例,研究盾构工作井在未施作主体内衬结构状态下实现盾构始发与接收时的围护结构受力及变形情况,并分析了盾构始发与接收对围护结构稳定性的影响。[结果及结论]研究结果表明:无内衬状态工作井盾构始发与接收时,围护结构桩体水平位移最大值及弯矩最大值均发生在盾构工作井端墙中跨第4道钢支撑处,围护结构剪力最大值发生在盾构工作井端墙中跨底板处;当盾构工作井未施作主体内衬结构时,围护结构桩体变形及受力均有所增大,但其位移及力学指标均满足规范要求;围护结构在剪力及弯矩作用下能够满足承载能力及强度要求;无内衬状态下的工作井盾构始发与接收可提高施工效率,有效节省工期,节约工程成本。

[Objective]Generally,shield machines are launched or received after completing the construction of shield working shaft main structure.However,due to various constraints,considering SLR(shield launching and receiving)beforehand is often necessary.Therefore,it is important to study the impact of SLR on shield working shaft retaining structure.[Method]Taking a standard three-storey island-type underground station of Chengdu Metro as example,the force and deformation of shield shaft retaining structure during SLR are studied when the main lining structure is not yet constructed.The impact of SLR on retaining structure stability is also analyzed.[Result&Conclusion]The research results indicate that:during SLR in an unlined working shaft,the maximum horizontal displacement and maximum bending moment of the retaining structure piles both occur at the fourth steel support of the shield working shaft end wall.The maximum shear force of the retaining structure occurs at the bottom plate of shaft end wall midspan.When main lining structure is not constructed for the shaft,the deformation and force of the retaining structure piles increase,but the displacement and mechanical indicators still meet the requirements of the specifications.The retaining structure can withstand the load and strength requirements under the action of shear force and bending moment.Therefore,SLR in an unlined shaft can improve construction efficiency,effectively saving construction time and reducing engineering costs.