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| Deformation and damage evolution law of shield tunnels crossing soft-hard heterogeneous strata under additional loads |
| Zhou Peng1,2
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1. China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, Hubei, China;
2. National-Local Joint Engineering Research Center of Underwater Tunnelling Technology, Wuhan 430063, Hubei, China |
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Abstract To reveal the longitudinal mechanical response and damage evolution law of shield tunnels in soft-hard heterogeneous strata, a refined three-dimensional longitudinal numerical model was established based on the engineering background of the Jinan Yellow River Jiluo Road Tunnel. After an overall damage index for the tunnel lining was adopted, the deformation characteristics, damage evolution laws, and failure mechanisms of the tunnel under the additional loads induced by riverbed siltation were systematically investigated. In addition, parametric sensitivity analyses of the longitudinal residual jacking force and bolt diameter were carried out. The results indicated that significant longitudinal non-uniform deformation at the soft-hard stratum interface was induced by the bearing capacity difference between the soft and hard strata. Opening on the hard soil side and dislocation on the soft soil side were exhibited by the circumferential joints, and these structural deformations were aggravated as the additional loads increased. The soft-hard stratum interface was identified as the most sensitive zone for structural deformation and damage accumulation. The compressive damage of the lining was mainly concentrated at the stratum interface, while tensile damage was predominantly distributed on the soft soil side. The transverse deformation of segment rings was verified to be the key factor inducing tensile failure of the tunnel lining. The longitudinal stiffness of the tunnel could be improved by both the longitudinal residual jacking force and the bolt diameter, whereas distinct mechanisms of action on structural responses were observed. A more significant effect on deformation control and damage evolution was exerted by the longitudinal residual jacking force than by the bolt diameter. The longitudinal deformation and circumferential joint dislocation were found to be reduced by the longitudinal residual jacking force, whereas local compressive damage and tensile damage on the soft soil side were aggravated by it. By contrast, the transverse deformation of segments was effectively restrained, and tensile damage was reduced by the increase in bolt diameter. It was demonstrated that the soft-hard stratum interface was regarded as the critical position for the safety control of shield tunnel structures, and the longitudinal residual jacking force was identified as a vital factor affecting the structural stress state and damage development. A reliable reference for the design, construction, and operational safety assessment of shield tunnels in soft-hard heterogeneous strata could be provided by the research results.
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Published: 12 October 2026
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