大直径盾构隧道斜螺栓环缝抗剪特性研究

以大直径盾构隧道施工过程中管片上浮错台问题为背景,研究大直径盾构隧道环缝结构的抗剪特性,从结构承载力角度提出有效且可控的抗浮措施,并深入探究环间错台对隧道结构的影响,以确定大直径盾构隧道环间变形控制标准,减小隧道环间错台引起的管片损伤。以深圳妈湾跨海通道为依托,基于材料塑性损伤本构,考虑管片接缝细部构造,根据相关管片环缝剪切原型试验对接缝抗剪数值模拟方法的有效性进行验证。随后,利用数值模拟研究了环向接缝顺剪、逆剪和切向剪切时的错台现象和破坏特征,分析了斜螺栓、凹凸榫对环缝抗剪特性的影响,为大直径盾构隧道环缝结构的抗浮设计和安全评价提供依据。研究表明:环缝剪切错台数值计算结果与试验结果吻合良好,能够有效揭示接缝剪切过程中结构的变形特点和损伤特性;环缝接缝的剪切错台过程较为复杂,呈阶段性特征,螺栓和凹凸榫的受力状态是决定接缝抗剪特性的关键因素;凹凸榫能显著提高接缝抗剪刚度和承载力,但也带来接缝应力集中和张开过大等问题,设计和施工过程中需充分考虑接缝刚度和变形的适应性;基于环缝错台损伤分析,提出了环缝变形的三级安全评价指标,大直径盾构隧道接缝变形必须控制在Ⅱ级以内,以保证隧道的结构安全和正常使用性能。

Shearing Behavior of Circumferential Joints with Oblique Bolts in Large Diameter Shield Tunnel

Based on the lining floating issue, which is often encountered during large-diameter shield tunneling, the shearing behavior of circumferential joint was studied to propose effective and controllable anti-floating measures from the perspective of structural bearing capacity. The influence of dislocation between segment rings on the tunnel structure was also analyzed to determine the control standards for the deformation of the circumferential joint and to reduce the segment damage caused by the dislocation. Based on the Mawan cross-sea project in Shenzhen, the segmental joint of large-diameter shield tunnel was finely simulated considering the plastic damage constitutive of the material and the structural details, and the numerical simulation method was verified according to the relevant prototype test of the shearing dislocation of the circumferential joint. Subsequently, the shear dislocation behavior and damage characteristics of the circumferential joints in ordinal, reverse, and tangential shearing modes were studied using numerical simulation method. The effects of oblique bolts and tenons on the shearing stiffness of circumferential joints were also analyzed, and the basis for anti-floating design and safety evaluation of the circumferential joint in large-diameter shield tunnel was provided. The obtained numerical simulation results of shearing dislocation of the circumferential join are in good agreement with the experimental results, and can effectively reveal the deformation and damage characteristics of the segmental structure. The dislocation process of circumferential joint is complicated and can be divided into several stages, and the stress state of oblique bolts and tenons are the key factors that determine the shear behavior of the joints. Tenons can enhance the shearing stiffness and bearing capacity of joints, and also cause stress concentration of segments and excessive joint opening. The relationship between the shearing stiffness of circumferential joints and deformation adaptability must be fully considered during design and construction. Finally, based on the damage analysis of the numerical simulation, an evaluation standard of the structural deformation of circumferential joints with three levels is proposed. The deformation of the circumferential joint must be restricted to level Ⅱ to ensure the structural safety and performance of the tunnel.