DBPapers
DOI: 10.5593/SGEM2015/B12/S2.063

NEW ADVANCED MATERIAL MODEL FOR NUMERICAL MODELLING OF SHALLOW TUNNEL IN SOFT CLAYS

J. Vesely
Friday 7 August 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-32-2 / ISSN 1314-2704, June 18-24, 2015, Book1 Vol. 2, 471-478 pp

ABSTRACT
This paper describes a newly developed advanced material model which can better simulate the real behaviour of the soil mass during the tunnel excavation and contains the following main features. Firstly, the model is based on the rounded Mohr-Coulomb (William-Warnke) failure yield criterion which eliminates the singular tips from the Mohr-Coulomb surface and has better agreement with the data from the experimental tests. Secondly, the model has the possibility to simulate the non-linear isotropic hardening and softening of the soils. Thirdly, it is capable to increase the stiffness modulus with increasing depth or stress level and finally the model has the ability to simulate the non-linear decrease of the stiffness modulus in a small strain range (0.0001 – 0.1%). The combination of these improvements caused that the width and the shape of the settlement troughs are more accurately modelled, the excavation heave is reduced to more realistic values and the results of the soil mass behaviour correspond more to the reality. To illustrate the functionality and practical use of this material model, the real project of the shallow tunnel (Dobrovskeho tunnel, Brno, Czech Republic) is chosen, the 3D numerical analysis is calculated and comparison between Mohr-Coulomb, newly developed model and monitoring field data is presented.

Keywords: advanced material model, tunnels, soft clays, numerical modelling