类矩形盾构隧道无立柱衬砌结构设计及参数研究

Design and Parameter Study of Pillarless Lining Structure for Quasi-rectangular Shield Tunnel

目的:类矩形无立柱盾构隧道适用于渡线段的应用,施工过程中施作立柱,在稳定阶段拆除立柱以达到最终运营稳定状态,全过程中存在结构受力机制的变化。为了形成适用于类矩形无立柱隧道结构的设计方法并探究不同参数的影响,有必要开展相关理论研究。方法:明确了类矩形盾构隧道无立柱衬砌结构在施工、运营全过程所受荷载状态;基于修正惯用法(等效刚度均质环模型)建立设计模型,探究了施工全过程及直接施加运营工况荷载2种不同工况下的结构响应,并与足尺试验结果进行了对比验证。基于设计模型,对侧压力系数、偏载值、结构埋深等多个关键因素开展了敏感性研究,分析了对衬砌结构受力及变形的影响。结果及结论:采用修正惯用法并直接施加最终运营阶段稳定荷载能满足类矩形盾构隧道无立柱衬砌结构的工程设计要求,但需要将设计值放大5%~10%,该结论也得到了足尺试验的支持。不同设计参数对结构响应的影响程度不同,其中单侧偏载和结构埋深对于设计的影响更大,同时进一步揭示了腰部负弯矩接头的薄弱特征。

Objective:The pillarless quasi-rectangular shield tunnels are suitable for application in crossover section.During the construction process,pillars are erected and then removed during the stabilization phase to achieve the final operational stable state.Throughout the entire process,there are changes in the structural force mechanism.To develop a design method applicable to pillarless quasi-rectangular shield tunnel structures and explore the influence of different parameters,it is necessary to conduct relevant theoretical research.Method:The load states of the pillarless lining structure for quasi-rectangular shield tunnels during construction and operation process is clarified.Based on the modified conventional method(equivalent stiffness homogeneous ring model),a design model is established to investigate the structural response under two different working conditions:the entire construction process and the direct application of operating load conditions.A comparison and validation with full-scale test results are performed.Using the design model,a sensitivity study is conducted on several key factors such as lateral pressure coefficient,eccentric load value,and structure buried-depth,analyzing their impact on force and deformation conditions of lining structure.Result and Conclusion:The research findings show that using the modified conventional method and directly applying stable loads in the final operation stage can satisfy the engineering design requirements for pillarless lining structures in quasi-rectangular shield tunnels.However,it is recommended to amplify the design values by 5%to 10%,a conclusion supported by full-scale tests.Different design parameters have varying degrees of impact on structural response,with unilateral eccentric load and structure buried-depth exerting greater influence on the design,and the vulnerable characteristics of the negative bending moment joint at the waist are further revealed.