【摘要】 盾构隧道沿纵向将不可避免地穿越多种地层，地基的非均质性和非连续性是广泛存在的。针对非均质地基中盾构隧道的纵向变形问题，将盾构隧道视为非均质Winkler地基中的Euler-Bernoulli梁，建立非均匀地基中盾构隧道纵向力学性能分析的非均质Winkler地基-EB梁模型，基于中心差分原理，推导得到解析模型控制方程的显式有限差分解。通过与既有研究成果的对比，验证解析模型的可靠性。而后，基于所建立的解析模型系统分析2类典型非均质地基条件下地基变异性对盾构隧道纵向变形和内力的影响，进一步讨论软硬地层渐变时隧道的纵向力学特性。研究结果表明：不同地基条件下所推导的有限差分解与既有有限元结果较为吻合，证明所建立的解析模型及其解答是准确可靠的；相邻地基刚度的差异会显著影响盾构隧道的纵向变形和内力，软硬地层交界面处隧道变形和内力会产生明显变化，且隧道剪力在此达到最大值，易产生环间错台等病害；对于软硬突变地层，隧道最大差异沉降随软弱地基刚度的减小线性增大，而最大弯矩和剪力的变化呈现出一定的非线性；对于含软弱层的软硬交替地层，软弱层相对刚度和相对长度均会显著影响隧道的纵向变形和内力，隧道最大差异沉降和最大弯矩及剪力随软弱层相对刚度和相对长度的变化具有明显的非线性特性；相比于软硬地层的突变，地层的渐变使得隧道剪力显著减小，有利于改善盾构隧道的纵向力学性能。更多还原

【Abstract】 The shield tunnels inevitably pass through a variety of strata along the longitudinal direction, and the heterogeneity and discontinuity of the foundations are widely encountered. Aiming at the issue of the longitudinal deformation of a shield tunnel lying in heterogeneous strata, a non-homogeneous Winkler foundation-EulerBernoulli(EB) beam model was established. The shield tunnel was treated as an EB beam resting on the nonhomogeneous Winkler foundation. Based on the principle of central difference, the explicit finite difference solution of the governing equation of the analytical model was derived. The reliability of the proposed model was validated by the existing research results. Then, systematic analyses were conducted on the influences of foundation variability on tunnel deformation, and internal forces were conducted using the proposed model under two typical non-homogeneous foundation conditions. Finally, the applicability of the analytical model to more complex heterogeneous foundations was discussed, as well as the longitudinal performance of the shield tunnel with gradual change of soft and hard strata. The results indicate that there are satisfied agreements between the derived finite difference solutions and the existing finite element method results, thus proving that the proposed analytical model and its solutions are reliable and accurate. The longitudinal deformation and internal forces of the shield tunnel are significantly affected by the difference of the foundation stiffness between the adjacent strata. Obvious variations of these responses would appear at the interfaces between the soft and hard strata and the shear force would reach its maximum, leading to disasters such as dislocation between the adjacent segmental rings. When a shield tunnel is lying on a soft-hard abrupt foundation, its maximum differential settlement increases linearly with decreasing stiffness of the soft layer, while the maximum bending moment and shear force vary nonlinearly. When a shield tunnel is lying on a non-homogeneous foundation containing a soft embedded layer, its longitudinal deformation and internal forces would be significantly affected by the relative stiffness and length of the embedded soft layer. As compared to the abrupt change of hard and soft strata, the gradual change of strata causes shear forces of the tunnel to reduce significantly, which is beneficial to improve the longitudinal mechanical properties of shield tunnels.更多还原