盾构隧道环间接头弯曲状态非线性研究

为探明盾构隧道环间接头抗弯性能在纵向弯矩、轴力组合作用下的状态非线性规律，将环间接头力学行为划分为7种变形模式及3种受力状态，分别推导了环间接头转角-纵向弯矩-纵向轴力三者关系的解析表达式与环间接头在不同弯曲状态间转变时的临界内力表达式，并以三维有限元计算对本文提出的解析公式进行验证。研究结果表明:盾构隧道特有的“管片环+接头”非连续结构形式导致环间接头弯曲行为具有状态非线性特征，不同弯矩、轴力组合作用下，盾构隧道环间接头变形模式于不同状态间转变并伴随抗弯刚度突变；纯弯作用下环间接头抗弯刚度为定值，轴向压力可使接头抗弯刚度较纯弯时提高数倍乃至无穷大；拉弯作用下接头抗弯性能维持在两个固定水平值之间，接缝面被完全拉开时环间接头抗弯刚度会随之被削弱数倍。

STUDY ON BENDING STATE NONLINEARITY OF SHIELD-TUNNEL RING JOINTS

In order to investigate the bending state nonlinearity of shield-tunnel ring joints under the composite action of longitudinal internal forces, the mechanical behavior of ring joints were classified to 7 deformation modes and 3 internal force states. The analytical expressions involved ring joints rotation angle and longitudinal internal forces for each deformation mode were derived. At the same time, the critical moment expression of the ring joints between different deformation modes was developed. FEM method was employed to verify the results obtained by an analytic derivation. The results showed that bending state nonlinearity was one inherent feature of ring joints because of the discontinuous structure of a shield tunnel. The deformation mode and bending stiffness of shield-tunnel ring joints changed under different internal force combinations. In a pure bending state, the ring joints' bending stiffness had a constant value, and it could be enlarged several times under a compression-bending state, even be enlarged to infinity. The bending stiffness of ring joints under a tension-bending state would be limited to two constant values which were both smaller than that under a pure bending state, and it would be decreased several times when ring joint surface was completely opened.