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Geomechanics and Engineering Volume 32, Number 2, January25 2023 , pages 145-157 DOI: https://doi.org/10.12989/gae.2023.32.2.145 |
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Face stability analysis of large-diameter underwater shield tunnel in soft-hard uneven strata under fluid-solid coupling |
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Shanglong Zhang, Xuansheng Cheng, Xinhai Zhou and Yue Sun
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| Abstract | ||
| This paper aims at investigating the face stability of large-diameter underwater shield tunnels considering seepage in soft-hard uneven strata. Using the kinematic approach of limit upper-bound analysis, the analytical solution of limit supporting pressure on the tunnel face considering seepage was obtained based on a logarithmic spiral collapsed body in uneven strata. The stability analysis method of the excavation face with different soft- and hard-stratum ratios was explored and validated. Moreover, the effects of water level and burial depth on tunnel face stability were discussed. The results show the effect of seepage on the excavation face stability can be accounted as the seepage force on the excavation face and the seepage force of pore water in instability body. When the thickness ratio of hard soil layer within the excavation face exceeds 1/6D, the interface of the soft and hard soil layer can be placed at tunnel axis during stability analysis. The reliability of the analytical solution of the limit supporting pressure is validated by numerical method and literature methods. The increase of water level causes the instability of upper soft soil layer firstly due to the higher seepage force. With the rise of burial depth, the horizontal displacement of the upper soft soil decreases and the limit supporting pressure changes little because of soil arching effect. | ||
| Key Words | ||
| arching effect; face stability; limit analysis; numerical analysis; seepage; soil underwater tunnel; upper-soft and lower-hard strata | ||
| Address | ||
| Shanglong Zhang, Xinhai Zhou and Yue Sun: Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, No. 287, Langongping Road, Lanzhou 730050, China Xuansheng Cheng: Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, No. 287, Langongping Road, Lanzhou 730050, China; Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, No. 287, Langongping Road, Lanzhou 730050, China | ||