盾构隧道开口对其纵向抗弯刚度的影响试验

Effect of Segment Ring Opening of Shield Tunnel on Its Longitudinal Bending Rigidity

盾构隧道建成后,由于某些功能需求而需要在盾构隧道的不同位置处开口,如两平行盾构隧道之间施工联络通道、盾构隧道底部施工暗井泵房以及盾构隧道顶部施工竖井。针对盾构隧道开口后纵向刚度降低,易发生纵向不均匀沉降或水平挠曲变形等问题,设计了几何相似比为1∶10的模型盾构隧道,开展了盾构隧道不同位置开口(顶部开口、侧部开口以及底部开口3种情况)对其纵向刚度影响的试验研究。采用简支梁法,对盾构隧道不同位置开口与隧道未开口实测结果进行了对比分析,探究了模型隧道环缝接头张开量、开口位置张开量以及不同位置开口后对其纵向抗弯刚度的影响。对开口后隧道不同方向的抗弯刚度进行测试,分析结果表明:当开口位置方向受压时刚度降低90.5%,开口位置方向受拉时刚度降低64.6%,隧道弯曲方向与开口位置垂直时其刚度降低42.4%;盾构隧道开口后,由于开口处环缝连接螺栓的拆除而导致盾构隧道抗弯刚度降低;相对完整的盾构隧道弯曲过程中,不同开口处对应刚度发挥作用不同,因此对盾构隧道的刚度降低程度也有所不同;盾构隧道开口后,隧道的抗弯刚度与其弯曲方向和开口相对位置相关,在盾构隧道受荷变形分析、抗震分析中应根据隧道的弯曲方向对盾构隧道抗弯刚度进行取值。

After the completion of the shield tunnel,owing to certain functional requirements,opening at different positions of the shield tunnel,such as the construction of the channel connecting the two parallel shield tunnels,the construction of the underground shaft pump room at the bottom of the shield tunnel,and the construction of the shaft at the top of the shield tunnel are necessary.This study sets up three different openings at the same position of the shield tunnel:the top,side,and bottom openings.To resolve the problem caused by the reduction in the longitudinal rigidity of shield tunnel after opening,which is prone to longitudinal uneven settlement or horizontal deflection deformation,a model shield tunnel with a geometric similarity ratio of 1:10 was designed,and the influence of openings at different positions of the shield tunnel on its longitudinal rigidity was carried out.The simply supported beam method was used to compare and analyze the measurements of the openings at different positions of the shield tunnel and unopened tunnel.The influence of the opening extent of the annular joint,opening position,and opening at different positions on the longitudinal bending rigidity of the model tunnel were analyzed.The bending rigidity of the tunnel in different directions after opening was tested.The results show that rigidity decreases by 90.5%when the opening position is compressed,64.6%when the opening position is tensioned,and 42.4%when the bending direction of the tunnel is perpendicular to the opening position.After the opening of the shield tunnel,the bending rigidity of the shield tunnel is reduced owing to the removal of the ring joint connection bolts at the opening.In the bending process of the relatively complete shield tunnel,the corresponding rigidity at different openings plays different roles;therefore,the degree of rigidity reduction of the shield tunnel varies.After the shield tunnel is opened,the bending rigidity of the tunnel is related to its bending direction and the relative position of the opening.In the analysis of the load deformation and seismic analysis of the shield tunnel,the bending rigidity of the shield tunnel should be determined according to the bending direction of the tunnel.