盾尾非对称推力作用下盾构隧道纵向变形分析

盾构机在沿曲线掘进或轴线纠偏过程中，盾尾非对称推力会在管片端部产生附加弯矩，从而引起隧道发生纵向变形。现有解析方法多是将盾构隧道简化为等效连续梁，不能考虑隧道管片环间接头的弱化。首先，建立一种能够同时考虑环间张开和剪切错台的简化纵向梁-弹簧盾构隧道模型（simplified longitudinal beam-spring shield tunnel model，简称SLBSM）；其次，将在建隧道简化为Winkler地基上的SLBSM，采用状态空间法推导了非对称推力作用下盾构隧道纵向变形解析解答。通过与既有文献有限元及现有两种连续梁模型计算结果进行对比，验证了所提方法的可靠性和适用性，并对部分参数进行敏感性分析。研究结果表明：连续梁模型计算得到的隧道纵向位移表现为连续特征，而所提方法得到的隧道纵向位移表现为非连续特征，隧道纵向位移在接头处会发生突变；通过参数分析可知：增大接头转动刚度可有效降低隧道隆起和环间张开量；增大接头剪切刚度可有效降低环间错台量，但会导致隧道隆起和剪力的增加；增大地基刚度能显著降低隧道环间张开量和隆起，但会导致环间错台量的增加；管片始端轴力对隧道纵向变形的影响不可...

Analysis of longitudinal deformation of shield tunnel subjected to shield tail asymmetric thrust

When the shield machine is driving along a curve alignment or during deviation correction, the asymmetrical thrust will generate an additional bending moment on the head of the tunnel ring, which will cause longitudinal deformation of the shield tunnel. Current analytical methods commonly simplify the existing tunnel as an equivalent continuous beam, which will overlook the weakening of the circumferential joint. In this study, a simplified longitudinal beam-spring shield tunnel model (SLBSM) is established, which can simultaneously consider the opening and dislocation between segmental rings. Then, the shield tunnel under construction is simplified as a SLBSM resting on the Winkler foundation. The shield tunnel longitudinal deformation subjected to the shield tail asymmetric thrust is solved using the state space method; the reliability and applicability of the proposed method are verified by comparing with the results from finite element analysis and two existing continuous beam model. The parametric analysis is further performed to investigate the influences of some parameters on the deformation of shield tunnel. The results show that the longitudinal displacement of shield tunnel based on the continuous beam model exhibits continuous characteristics. While the longitudinal displacement predicted by the proposed method exhibits discontinuous characteristics, “gaps” appear at the joints between adjacent rings. Through the parametric analyses, it is found that increasing the rotation stiffness of the circumferential joint will effectively reduce the tunnel heave and opening of joint; increasing the shearing stiffness of the circumferential joint will effectively lead to the decrease of dislocation between adjacent rings, but it will increase the tunnel heave and shear force; improving the foundation stiffness will effectively reduce the tunnel heave and opening of joint, but it will result in the increase of the dislocation between adjacent rings. The effect of the axial force at the beginning of the segment on the longitudinal deformation of the tunnel cannot be ignored. Increasing the axial force will effectively reduce the tunnel heave, opening of joint, and dislocation between adjacent rings.