【摘要】 地质条件、附加荷载以及约束条件等变化易使盾构隧道纵向产生不均匀变形，引发接缝渗漏，施加纵向预应力可以有效解决这一问题。为探究预应力盾构隧道的纵向力学特性，针对完全闭合、部分张开2种环缝接触状态下的预应力盾构隧道建立纵向等效刚度梁模型，基于提出的7个纵向变形控制指标，结合上海某越江隧道工程实例，优化确定隧道的最佳纵向预应力，分析最佳预应力对超限纵向弯矩的影响。研究结果表明：某越江隧道在最佳预应力9.24 MN下的纵向抗弯刚度及纵向曲率半径均大幅增加，且环缝变形量减小99.67%，环缝密封性显著提升；最佳预应力盾构隧道在纵向弯曲过程中，纵向曲率半径先达到界限值15 000 m，随后部分螺栓进入屈服状态、环缝张开量相继达到2 mm、6 mm，混凝土应力达到抗压强度，最后部分螺栓达到抗拉变形量发生破坏；与非预应力盾构隧道相比，最佳预应力隧道的超限纵向弯矩和抗弯刚度增大2.46～9.33倍，纵向承载能力显著增强，但纵向曲率半径减小了2.13%～6.70%。建议通过施加纵向预应力降低盾构隧道纵向不均匀变形，在施加过程中，重点关注隧道纵向曲率半径和螺栓应力的变化。更多还原

【Abstract】 Changes in geological conditions, additional loads and constraints often cause uneven longitudinal deformation in shield tunnels, leading to joint leakage. Applying longitudinal prestress effectively addresses this issue. To investigate the longitudinal mechanical properties of prestressed shield tunnels, the longitudinal equivalent stiffness beam models for tunnels were established in two contact states of the circumferential seam of fully closed and partially open. Based on seven proposed longitudinal deformation control indices, and by optimizing the best longitudinal prestress through a case study of a cross-river tunnel project in Shanghai, the influence of optimal prestress on excessive longitudinal bending moments was analyzed. The results show that under an optimal prestress of 9.24 MN, both the longitudinal bending stiffness and curvature radius significantly increase, reducing the circumferential seam deformation by 99.67% and substantially improving the tightness of circumferential seam. During the longitudinal bending process of the optimal prestressed shield tunnel, the longitudinal curvature radius first reaches the limit value of 15 000 m, followed by some bolts entering the yield state, and the opening of the circumferential seam successively reaching 2 mm and 6 mm. Concrete stress reaches the compressive strength, and eventually, some bolts fail due to the tensile deformation. Compared to nonprestressed shield tunnels, the optimal prestressed tunnel shows a 2.46 to 9.33 times increase in excessive longitudinal bending moment and bending stiffness, significantly enhancing the longitudinal load-bearing capacity,though the longitudinal curvature radius decreases by 2.13% to 6.70%. Applying longitudinal prestress is recommended to reduce uneven longitudinal deformation in shield tunnels, with special attention to changes in the tunnel’s longitudinal curvature radius and bolt stress during the application process.更多还原