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<p>With the increasing intensity of urban underground space development, the super-small spacing overlapping tunnel group has emerged as a preferred structural solution for urban rail transit systems. However, its construction disturbance effect and the interaction between tunnels need to be further explored. To study the construction deformation behaviors of super-small spacing overlapped tunnel under interactive effects, this study employs FLAC3D three-dimensional numerical modeling based on the Phase I project of Chongqing Rail Transit Line 17. The research systematically reveals the deformation characteristics and interaction mechanisms during the construction of the super-small spacing overlapping tunnels. Key findings include: (1) During the advancement of the upper tunnel excavation face, the vertical deformation of the vault of the existing tunnel initially exhibits heave followed by subsequent settlement. Meanwhile, the horizontal deformation at the haunches develops outward, displaying a characteristic "S"-shaped evolutionary trend. (2) The upper tunnel's crown vertical deformation follows a distinct "S"-shaped curve, with the near area of the tunnel face is more than 70% of total settlement. Conversely, the invert demonstrates an "uplift-deformation-re-uplift" triphasic evolution, while haunch horizontal deformation rates exhibit a negative correlation with face length. (3) The surface settlement trough exhibits a characteristic Gaussian distribution, with a maximum settlement of 1.694&#xa0;mm. The deviation from Peck's empirical formula predictions is merely 0.22&#xa0;mm, demonstrating excellent agreement with numerical modeling results. The interaction mechanism of the construction deformation of the overlapped tunnel is reflected in the stress disturbance and displacement transfer effect of the first built down tunnel on the surrounding rock of the later built-up tunnel, and the additional stress effect of the later built tunnel on the existing tunnel structure through reverse load transfer. The research results provide a theoretical basis for the deformation control of the construction of similar super-small spacing overlapping tunnel groups, and have important reference value for ensuring the safety construction of urban underground engineering.</p>

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Study on Construction Deformation Behavior of Super-Small Spacing Overlapped Tunnel Under Interactive Influence

  • 期刊论文

  • 发表日期：

    2025年10月22日

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  • Junyang Fei,
  • Rui Su,
  • Xiang Chen,
  • Tao Deng,
  • Xianhu Zhou,
  • Junjie Huang

摘要

With the increasing intensity of urban underground space development, the super-small spacing overlapping tunnel group has emerged as a preferred structural solution for urban rail transit systems. However, its construction disturbance effect and the interaction between tunnels need to be further explored. To study the construction deformation behaviors of super-small spacing overlapped tunnel under interactive effects, this study employs FLAC3D three-dimensional numerical modeling based on the Phase I project of Chongqing Rail Transit Line 17. The research systematically reveals the deformation characteristics and interaction mechanisms during the construction of the super-small spacing overlapping tunnels. Key findings include: (1) During the advancement of the upper tunnel excavation face, the vertical deformation of the vault of the existing tunnel initially exhibits heave followed by subsequent settlement. Meanwhile, the horizontal deformation at the haunches develops outward, displaying a characteristic "S"-shaped evolutionary trend. (2) The upper tunnel's crown vertical deformation follows a distinct "S"-shaped curve, with the near area of the tunnel face is more than 70% of total settlement. Conversely, the invert demonstrates an "uplift-deformation-re-uplift" triphasic evolution, while haunch horizontal deformation rates exhibit a negative correlation with face length. (3) The surface settlement trough exhibits a characteristic Gaussian distribution, with a maximum settlement of 1.694 mm. The deviation from Peck's empirical formula predictions is merely 0.22 mm, demonstrating excellent agreement with numerical modeling results. The interaction mechanism of the construction deformation of the overlapped tunnel is reflected in the stress disturbance and displacement transfer effect of the first built down tunnel on the surrounding rock of the later built-up tunnel, and the additional stress effect of the later built tunnel on the existing tunnel structure through reverse load transfer. The research results provide a theoretical basis for the deformation control of the construction of similar super-small spacing overlapping tunnel groups, and have important reference value for ensuring the safety construction of urban underground engineering.