【摘要】 针对狭窄空间地铁车站施工困难以及明挖施工造成道路长期封堵等工程现状,提出采用顶管法结合超大直径盾构隧道暗挖地铁车站的工法。针对工法中拆除管片后,未拆除管片轴力骤降,附近纵缝剪切和抗弯性能降低的结构特性,同时也为体现管片空间力学特征,文章提出采用基于荷载-结构模式的壳-接触计算模型,研究在拆除管片和拆除内部支撑的两个关键工序中结构的整体力学性能,确定上述暗挖车站新工法隧道开口时衬砌管片、管片接缝和内支撑体系协同受力特征,并据此提出结构优化方向:(1)调整衬砌开口位置上部第一个纵缝,使其远离开口上边缘,可明显减小衬砌结构变形,降低该纵缝环向螺栓拉力;(2)建议在拆除内部支撑、完成顶管通道与盾构隧道连接之后,再施作车站中板;(3)顶管通道与盾构隧道衬砌实际连接形式难以确定,建议设计时取刚接、铰接包络设计;(4)增强衬砌环间整体性可有效控制结构响应。更多还原

【Abstract】 Aiming at the difficulty of narrow space subway station construction and the long-term road blocking caused by open excavation in subway construction, a method of pipe jacking combined with large diameter shield tunneling was proposed. In view of the structural characteristics of abrupt drop in axial force of the unremoved segement in the construction, resulting in abrupt change in shear and flexural performance of adjacent longitudinal joints, a shell-contact calculation model based on load-structure model was proposed in this paper. This paper studies the mechanical properties of the whole structure in the two key processes of removing the segment and removing the internal support. The cooperative laws of lining segments, segment joints and internal support system during the tunnel opening were obtained, and the structural optimization direction was put forward accordingly.(1)By adjusting the first longitudinal joint above the opening position away from the upper edge of the opening, the deformation of the opening lining ring and the bolt tension of the longitudinal joint could be sinnificantly reduced.(2)It was suggested to construct the station midboard after removing the internal support and completing the connection between passage and shield tunnel.(3)It was difficult to determine the actual connection between passage and shield tunnel lining, so it is suggested to adopt the rigid joint and hinged enveloping design.(4)The structural mechanical responses could be effectively controlled by enhancing the integrity between openings lining rings.更多还原