Stability analysis of shotcrete supported crown of NATM tunnels with discontinuity layout optimization |
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| Authors: | Yiming Zhang Xiaoying Zhuang Roman Lackner |
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| Institution: | 1. School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin, P.R. China;2. Institute of Continuum Mechanics, Leibniz Universit?t Hannover, Hannover, Germany;3. Department of Geotechnical Engineering, Tongji University, Shanghai, P.R. China;4. State Key Laboratory of Disaster Reduction in Civil Engineering, Shanghai, P.R. China;5. Material‐Technology Innsbruck (MTI), University of Innsbruck, Innsbruck, Austria |
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| Abstract: | For tunnel constructed by New Austrian Tunnelling Method, the crown is the upper part of tunnel section, constructed during excavation process and supported by shotcrete. The stability of the crown has great influence on the safety of tunnel itself and the buildings above, which correlates, among others, with geometrical setup of tunnel and material properties of shotcrete and soil/rock. In this paper, aiming at analyzing the stability of shotcrete supported crown, a recently presented numerical method discontinuity layout optimization is adopted, which introduces a great amount of potential discontinuities cross over one another and provides a wide search space for efficient upper limit analysis. In the analysis, a well‐established hydration model of cementitious material is implemented for accounting the hydration of shotcrete. Then assumptions based on convergence‐confinement method are used for accounting the 3‐dimensional effect in 2‐dimensional analysis, finally providing time‐space–dependent assessments of stability of shotcrete supported crown. |
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| Keywords: | discontinuity layout optimization (DLO) factor of safety failure mechanism stability analysis Mohr‐Coulomb failure criteria |
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