软土地区通缝拼装地铁盾构隧道管片纵缝接头的优化

Optimization for Longitudinal Segment Joint of Metro Shield Tunnel with Straight Joint in Soft Soil Area

针对软土地区地铁盾构隧道管片纵缝接头因地表超载易发生破损的问题,考虑软土地层的特性,提出在软土地区盾构隧道横向刚度设计中,采用加大隧道结构刚度和强度的"刚性衬砌"设计理念,对管片纵缝接头进行优化。通过局部或者整体增加管片的厚度,均可增加管片纵缝接头的抗弯刚度,从而明显减小管片环的变形,虽然由此使得管片环的弯矩有所增大,但管片环变形减小的幅度远大于其弯矩增大的幅度;分别设计外张纵缝接头与内张纵缝接头连接螺栓的位置,纵缝接头的连接螺栓应靠近接头张开的一侧;在管片环分块时尽量将管片纵缝接头设计在弯矩较小的位置,同时在满足施工的条件下,尽量减少管片环的分块数量;局部加强纵缝接头位置的管片棱角,以预防管片接头棱角破损;通过合理设计防水密封垫的位置及断面形式,加强盾构隧道管片纵缝接头的防水能力。

The longitudinal segment joint of metro shield tunnel in soft soil area is prone to damage because of the overloading of ground surface.Considering the characteristics of soft soil stratum,the longitudinal segment joint is optimized by the proposed concept of＂rigid lining＂in the design for the transverse rigidity of shield tunnel in soft soil area,which increases the rigidity and strength of tunnel structure.The flexural rigidity of longitudinal segment joint can be increased by increasing segment thickness locally or integrally,thus the deformation of segment ring is obviously reduced.Although the bending moment of segment ring is generally increased,the decrease amplitude for segment ring deformation is much larger than that for its bending moment.The positions of the connecting bolts between externally or internally open longitudinal joints are designed respectively,and the connecting bolt should be close to the open side of the joint.When the segment ring is divided into blocks,the longitudinal segment joint should be designed at the position of smaller bending moment as possible.At the same time,in order to meet construction conditions,the block number of segment ring should be decreased.The edges and corners of longitudinal segment joint are partly strengthened so as to prevent them from being damaged.The waterproof capability of the longitudinal segment joint of metro shield tunnel can be strengthened through reasonably designing the position and cross section form of waterproof gasket.