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  • 1
    Electronic Resource
    Electronic Resource
    Computational mechanics of the excavation of tunnels (1996)
    Bradford : Emerald
    Engineering computations 13 (1996), S. 49-69 
    Details
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Contains a report on three-dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels. Multisurface elasto-viscoplastic material models are employed for consideration of the mechanical behaviour of the soil and the shotcrete shell supporting the excavation. Both are formulated within the framework of closest point projection algorithms. For soil a cap model is used, consisting of a curved failure surface, a tension cut-off and an elliptical cap. The latter allows consideration of the evolution of plastic strains even for the limiting case of a purely volumetric stress state. The movement of the cap is governed by a hardening law, describing the relation between the hydrostatic pressure and void ratio. The shotcrete model is a rotating crack model, taking ageing of the maturing concrete into account. It consists of a strain-hardening Drucker-Prager cone and three Rankine (crack) surfaces. Demonstrates the usefulness of the cap model to predict the mechanical behaviour of the soil by means of tests on remoulded, saturated clay. The model parameters of the clayey silt of Vienna, where the analysed tunnel is located, are fit to standard test results. The parameters of the shotcrete model are fit to test results published in the literature. Compares the analysis of a single-track tunnel with the results of field measurements from sliding micrometers. Furthermore, the stresses in the shotcrete lining are examined. In view of the inhomogeneity of the material and of unavoidable deficiencies of the measurements it is fair to say that the mechanical effects resulting from the excavation of tunnels are modelled reasonably well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/02644409610151557
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    NUMERICAL ANALYSES OF TUNNEL LININGS BY MEANS OF A VISCOPLASTIC MATERIAL MODEL FOR SHOTCRETE (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 3145-3162 
    Details
    ISSN: 0029-5981
    Keywords: shotcrete ; tunnelling ; cap model ; New Austrian Tunnelling Method (NATM) ; finite element method ; viscoplasticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper is concerned with the parameter identification, verification and selected applications of a 3D viscoplastic material model for shotcrete proposed by Meschke. The performance of the shotcrete model is evaluated by means of reanalyses of short-term and creep tests on shotcrete specimen. The most essential items of a viscoplastic cap model used for the representation of soil including the determination of the model parameters are also presented. Both models are employed in a 3D finite element simulation of the excavation of a single-track tunnel driven according to the New Austrian Tunnelling Method. Comparisons between in situ measurements and numerical results are presented.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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