集中力下通缝拼装管片协同变形与受力特性试验

Experiment on Co-deformation and Stress Characteristics of Through-joint Assembled Segments under Concentrated Force

  • 摘要: 为给近接通缝拼装盾构隧道的设计与施工提供变形控制理论依据,并突破传统模型试验方法的局限,自主研发出一整套集加载装置、模型管片、围压计算方法与监测系统为一体的模型试验方法,实现对盾构管片环缝与纵缝错台、收敛变形、管片径向位移及围压的同步测量。通过开展通缝拼装盾构管片模型试验,结果表明:在单点集中荷载作用下,隧道纵向挠曲变形、环缝错台与收敛变形近似呈线性正相关;在分级荷载作用下,加载环及奇数环各纵缝错台量近似从拱底加载点沿顺时针方向向上逐渐减小。各环管片作用反力的分布特征大致相同,每环上作用力大小依次是270°>202.5°>135°>22.5°>337.5°>67.5°,最大作用力位于左侧拱腰;管片内弧面中心点应变与管片作用力分布及发展规律相似,每环相同位置处管片的应变沿纵向近似服从正态分布,表明在已知加载环管片中心点的应力时,可以推算单点集中对称荷载作用下各环管片的内力。该试验方法适用于多种拼装方式的盾构隧道力学行为研究,能直观观测试验现象与结果,还可动态调整位移监测元件,监测更为便捷。

     

    Abstract: To establish a theoretical basis for deformation control in the design and construction of near-joint assembled shield tunnels, and to advance beyond traditional model testing approaches, this study independently developed a novel model testing method. This method integrates loading devices, model segments, confining pressure calculation, and a monitoring system. Model tests on near-joint assembled shield segments were conducted. The results preliminarily indicated that under a single-point concentrated load, the longitudinal deflection deformation of the tunnel, the circumferential joint misalignment, and the convergence deformation were approximately linearly and positively correlated. Under graded loading, the misalignment of each longitudinal joint in the loaded ring and the odd-numbered rings gradually decreased clockwise from the loading point at the arch bottom. The distribution characteristics of the reaction forces on segments within each ring were largely consistent. The magnitude of segment reaction forces followed the order: 270° > 202.5° > 135° > 22.5° > 337.5° > 67.5°, with the maximum reaction force located at the left arch waist. The strain at the center point of the inner arc surface of each segment exhibited distribution characteristics and a development law similar to those of the segment reaction forces. The strain of segments at the same position in each ring approximately followed a normal distribution along the longitudinal direction. Therefore, when the stress at the center point of each segment in the loaded ring is known, the internal forces of segments in each ring under a single-point concentrated symmetrical load can be calculated. This testing method is not only applicable to mechanical research on shield tunnels with various assembly methods but also, compared to tests on tunnels in soil, allows for more intuitive observation of test phenomena and results. Furthermore, it enables dynamic adjustment of displacement monitoring elements, making monitoring more convenient.

     

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