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Keywords: mechanized tunneling, numerical simulation, parameter adaptation.

Summary

The paper presents a three-dimensional finite element model for analyzing mechanized tunneling in urban areas. The numerical model represents the typical characteristics of the tunneling process by means of a slurry shield tunnel boring machine (slurry shield TBM).

Three different constitutive models were used for the mechanized tunneling simulation. The well-known linear elastic perfectly-plastic Mohr-Coulomb model is not well suited for modeling tunnel excavation problems. Therefore advanced models such as those available in the PLAXIS material model library, namely the Hardening Soil model (HS) and the Hardening Soil model with small-strain stiffness (HS-small) [1,2,3], are required in order to obtain realistic predictions of deformations during shield tunneling. In other words the realistic predictions for the deformations during shield tunneling may be achieved if the soil constitutive model employed takes into account at least:

the non linearity of the stress-strain curve and the stress dependency of the soil stiffness moduli;
the different stiffness during loading and unloading.

Additionally if the soil model does not take into consideration the nonlinear soil behaviour at small strains this leads to a considerably too soft response of the system, i.e. the calculated deformations are overestimated. Therefore from the three soil constitutive models presented in this paper for simulating the shield tunneling process the most adequate is the HS-small model. Different possibilities for the modeling of the grouting pressure are briefly presented, compared and their advantages and disadvantages are discussed.

References

1: T. Schanz, P.A. Vermeer, P.G. Bonnier, "The Hardening Soil Model: Formulation and verification", Beyond 2000 in Computational Geotechnics - 10 Years of PLAXIS, 1999.
2: T. Benz, R. Schwab, P. Vermeer, "Small-Strain Stiffness in Geotechnical Analyses", Bautechnik, 86, 16-27, 2009. doi:10.1002/bate.200910038
3: R.B.J. Brinkgreve, E. Engin, W.M. Swolfs, "PLAXIS 3D Version 2010, Material Models Manual", Netherlands, 2010.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 96 PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping and Y. Tsompanakis Paper 223 Three-Dimensional Finite-Element Analysis of Mechanized Shield Tunneling in Urban Areas V. Zarev¹, T. Schanz¹ and M. Datcheva² ¹Chair for Foundation Engineering, Soil and Rock Mechanics, Ruhr-Universität Bochum, Germany ²Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, Bulgaria doi:10.4203/ccp.96.223 purchase the full-text of this paper Full Bibliographic Reference for this paper V. Zarev, T. Schanz, M. Datcheva, "Three-Dimensional Finite-Element Analysis of Mechanized Shield Tunneling in Urban Areas", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 223, 2011. doi:10.4203/ccp.96.223 Keywords: mechanized tunneling, numerical simulation, parameter adaptation. Summary The paper presents a three-dimensional finite element model for analyzing mechanized tunneling in urban areas. The numerical model represents the typical characteristics of the tunneling process by means of a slurry shield tunnel boring machine (slurry shield TBM). Three different constitutive models were used for the mechanized tunneling simulation. The well-known linear elastic perfectly-plastic Mohr-Coulomb model is not well suited for modeling tunnel excavation problems. Therefore advanced models such as those available in the PLAXIS material model library, namely the Hardening Soil model (HS) and the Hardening Soil model with small-strain stiffness (HS-small) [1,2,3], are required in order to obtain realistic predictions of deformations during shield tunneling. In other words the realistic predictions for the deformations during shield tunneling may be achieved if the soil constitutive model employed takes into account at least: the non linearity of the stress-strain curve and the stress dependency of the soil stiffness moduli; the different stiffness during loading and unloading. Additionally if the soil model does not take into consideration the nonlinear soil behaviour at small strains this leads to a considerably too soft response of the system, i.e. the calculated deformations are overestimated. Therefore from the three soil constitutive models presented in this paper for simulating the shield tunneling process the most adequate is the HS-small model. Different possibilities for the modeling of the grouting pressure are briefly presented, compared and their advantages and disadvantages are discussed. References 1 T. Schanz, P.A. Vermeer, P.G. Bonnier, "The Hardening Soil Model: Formulation and verification", Beyond 2000 in Computational Geotechnics - 10 Years of PLAXIS, 1999. 2 T. Benz, R. Schwab, P. Vermeer, "Small-Strain Stiffness in Geotechnical Analyses", Bautechnik, 86, 16-27, 2009. doi:10.1002/bate.200910038 3 R.B.J. Brinkgreve, E. Engin, W.M. Swolfs, "PLAXIS 3D Version 2010, Material Models Manual", Netherlands, 2010. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £130 +P&P)
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