为揭示不同地基条件对预制综合管廊结构和接头受剪性能的影响规律，进一步提升地下综合管廊的韧性，以包头市新都市区地下综合管廊项目为背景，开展基床弱化条件下预制综合管廊承插接头的剪切模型试验和三维精细化数值模拟。对比分析4种工况下预制综合管廊承插接头的破坏特征及抗剪刚度的差异性，揭示出地基基床系数弱化对预制综合管廊力学性能的影响。研究结果表明： 1）地基基床系数越小，管廊承插接头的破坏范围越大、破坏程度越严重，承口倒角部位的混凝土破坏最为严重，更容易发生应力集中； 2）基床弱化会减弱地基对管节间错台变形的约束作用，与CD-1（砾砂）相比，CD-2（折减3/9刚度）、CD-3（折减5/9刚度）、CD-4（折减9/9刚度）错台量分别增加0.7%、3.4%、13.6%； 3）不同土层中接头的剪力-错台量曲线均分为部分滑移、整体滑移、破坏发展3个阶段，基床系数弱化后，地基在相同错台量下提供的反力减小，导致管廊剪切刚度降低； 4）基床系数的弱化使得管节承插口间的接触面积与接触压力增大，最大接触压力主要分布在接头的倒角位置，进而导致各舱室收敛变形增大，大、小舱室顶、底板均受拉，向管内变形，侧壁均向外凸起变形。
To investigate how varying
foundation conditions affect the shear performance of prefabricated utility
tunnel structures and their joints, a case study is conducted on an underground
utility tunnel project in the Baotou New Urban District. Shear model tests and three-dimensional refined numerical
simulations are conducted on socket joints under weakened foundation bed
conditions. By analyzing the failure patterns and shear stiffness differences
of these joints across four scenarios (CD-1 to CD-4), the influence of weakened foundation bed coefficients on the
mechanical performance of prefabricated utility tunnels is uncovered. Key
insights are as follows: (1) Lower foundation bed coefficients expand joint
failure zones and exacerbate damage, particularly at the chamfered regions of
the socket mouths, which are prone to stress concentrations. (2) Weaker
foundation beds reduce resistance to segment dislocations, with dislocations
increasing by 0.7% in CD-2 (3/9 stiffness loss), 3.4%
in CD-3 (5/9 loss), and 13.6% in CD-4 (9/9 stiffness loss) compared to the baseline CD-1 (gravel sand). (3) All joints exhibit a three-stage shear-dislocation behavior, including
partial slip, global slip, and progressive failure. The weakened foundation
beds lower the foundation counterforce at equal dislocation levels, reducing
the overall shear stiffness. (4) Weakened foundation bed coefficients boost
contact pressure and area between socket interfaces, peaking at chamfered
regions. This drives convergent deformation: the roof/floor slabs bend inward
under tension, while the sidewalls bulge outward across all tunnel
compartments.
