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<p>The long-term safety of metro tunnels adjacent to deep excavations in soft soil regions is significantly limited by soil rheological behavior. In this study, the multiscale creep mechanism of Fuzhou mucky soft soil and its effect on the soil–pit–tunnel system were investigated through laboratory tests and numerical simulations. First, one-dimensional consolidation creep tests and scanning electron microscopy (SEM) were conducted. Microscopic analysis revealed that creep deformation is intrinsically governed by the structural transition from a loose, flocculated arrangement to a densified fabric with face-to-face particle contacts. On the basis of the experimental results, the Bailey–Norton creep parameters were determined and incorporated into a finite element model. The simulation results indicated that the tunnel exhibited maximum settlement at the crown and lateral displacement at the waist. Compared with field monitoring, incorporating creep effects significantly improved the prediction accuracy and reduced displacement errors from 12.5 to 15.8% (without creep) to 2.5–6.7% (with creep). Furthermore, via a sensitivity analysis, the stress exponent (<i>n</i>) was identified as the dominant factor that controls tunnel deformation, where a 10% increase in <i>n</i> led to an increase in the displacement of approximately 29%. Finally, an optimized support system with additional cross-struts was proposed, which reduced the maximum tunnel deformation by approximately 27%, thereby ensuring the long-term postconstruction stability of the metro tunnel.</p>

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Effects of Soil Creep on the Excavation Induced Responses of Existing Tunnels in Soft Ground

  • 期刊论文

  • 发表日期：

    2026年2月23日

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  • Zhibo Chen,
  • Jiayu Wang,
  • Guangwei Cao,
  • Jinhuo Zheng,
  • Daigui Huang,
  • Xuanming Ding

摘要

The long-term safety of metro tunnels adjacent to deep excavations in soft soil regions is significantly limited by soil rheological behavior. In this study, the multiscale creep mechanism of Fuzhou mucky soft soil and its effect on the soil–pit–tunnel system were investigated through laboratory tests and numerical simulations. First, one-dimensional consolidation creep tests and scanning electron microscopy (SEM) were conducted. Microscopic analysis revealed that creep deformation is intrinsically governed by the structural transition from a loose, flocculated arrangement to a densified fabric with face-to-face particle contacts. On the basis of the experimental results, the Bailey–Norton creep parameters were determined and incorporated into a finite element model. The simulation results indicated that the tunnel exhibited maximum settlement at the crown and lateral displacement at the waist. Compared with field monitoring, incorporating creep effects significantly improved the prediction accuracy and reduced displacement errors from 12.5 to 15.8% (without creep) to 2.5–6.7% (with creep). Furthermore, via a sensitivity analysis, the stress exponent (n) was identified as the dominant factor that controls tunnel deformation, where a 10% increase in n led to an increase in the displacement of approximately 29%. Finally, an optimized support system with additional cross-struts was proposed, which reduced the maximum tunnel deformation by approximately 27%, thereby ensuring the long-term postconstruction stability of the metro tunnel.