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Geomechanics and Engineering Volume 33, Number 5, June10 2023 , pages 439-451 DOI: https://doi.org/10.12989/gae.2023.33.5.439 |
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Characterization of face stability of shield tunnel excavated in sand-clay mixed ground through transparent soil models |
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YuanHai Li, XiaoJie Tang, Shuo Yang and YanFeng Ding
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| Abstract | ||
| The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference. | ||
| Key Words | ||
| digital image correlation; face stability; modelling experiment; sand-clay mixed ground; shield tunnel; transparent soil | ||
| Address | ||
| YuanHai Li, XiaoJie Tang and YanFeng Ding: State Key Laboratory for Geomechanics and Deep Underground Engineering, Xuzhou, China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, China Shuo Yang: School of Civil Engineering, Xuzhou University of Technology, Xuzhou, China | ||