盾构隧道斜螺栓连接环缝剪切破坏特征理论解析

Theoretical Solution for Failure Mechanism of Circumferential Joint of Shield Tunnel Segment Connected Using Diagonal Bolts

为解决盾构隧道环缝接头在不均匀沉降作用下易发生破坏的问题,以某斜螺栓连接大直径盾构隧道环缝为例,通过足尺试验方法,揭示该隧道环缝的破坏机制,随后采用计算力学方法,将足尺试验获得的结论推广到构造类似的其他斜螺栓连接大直径盾构隧道环缝。研究结果表明:斜螺栓连接大直径盾构隧道环缝的破坏过程分为3个阶段,第1阶段环间剪力由静摩擦力平衡,环缝抗剪刚度很大;第2阶段在环缝剪力几乎不增加的情况下错台有所发展,环缝抗剪刚度接近于0,主要是由于斜螺栓与螺栓孔之间的间隙;第3阶段环缝剪力增量由斜螺栓承担,环缝抗剪刚度随斜螺栓支撑条件以及塑性铰产生过程而变化。解析解与试验结果具有良好的匹配性。

Differential settlement can easily cause the failure of the circumferential joint of a shield tunnel.Herein,a case study is conducted on the circumferential joint of a shield tunnel connected using diagonal bolts.The failure mechanism of the circumferential joint is revealed using a full-scale test.Thereafter,the results of the full-scale test are introduced to the circumferential joint of a large-diameter shield tunnel connected through bolts using a computational mechanics method.The results show the failure process of the circumferential joint of the large-diameter shield tunnel connected using diagonal bolts.Field data demonstrate that the circumferential joint is the weakness of the shield tunnel.The differential settlement arises along the longitudinal direction because of the dislocation on the circumferential joint.Thus,identifying the failure process of the circumferential joint in the following three stages is essential.(1)Stage 1,the circumferential shear stress is balanced through friction force,and the shear stiffness of the circumferential joint is large.(2)Stage 2,the dislocation phenomenon develops even when the shear stress of the circumferential joint does not increase,and the shear stiffness reaches zero due to the gaps between a diagonal bolt and the bolt hole.(3)Stage 3,the shear stress increment of the circumferential joint is borne by the diagonal bolt,and the shear stiffness of the circumferential joint varies with the support conditions of the diagonal bolt and plastic hinge.The analytical solution agrees with the test results.