Selected aspects of designing deep excavations

• Autorzy: Obrzud R. F. , Hartmann S. , Podleś K.

Identyfikatory

DOI

10.1515/sgem-2016-0024

• Języki publikacji: EN

Abstrakty

EN

This paper analyzes two approaches to serviceability limit state (SLS) verification for the deep excavation boundary value problem. The verification is carried out by means of the finite element (FE) method with the aid of the commercial program ZSoil v2014. In numerical simulations, deep excavation in non-cohesive soil is supported with a diaphragm wall. In the first approach, the diaphragm wall is modeled with the Hookean material assuming reduced average stiffness and possible concrete cracking. The sec-ond approach is divided into two stages. In the first stage, the wall is modeled by defining its stiffness with the highest nominal Young’s modulus. The modulus makes it possible to find design bending moments which are used to compute the minimal design cross-section reinforcement for the retaining structure. The computed reinforcement is then used in a non-linear structural analysis which is viewed as the “actual” SLS verification. In the second part, the paper examines the same boundary value problem assuming that the excavation takes place in quasi- impermeable cohesive soils, which are modeled with the Hardening Soil model. This example demonstrates the consequences of applying the steady-state type analysis for an intrinsically time-dependent problem. The results of this analysis are compared to the results from the consolidation-type analysis, which are considered as a reference. For both analysis types, the two-phase formulation for partially-saturated medium, after Aubry and Ozanam, is used to describe the interaction between the soil skeleton and pore water pressure.

Słowa kluczowe

EN

deep excavation; serviceability limit state; steady state analysis; consolidation analysis; undrained behavior analysis; ZSoil PC

• Wydawca: De Gruyter
• Czasopismo: Studia Geotechnica et Mechanica
• Rocznik: 2016
• Tom: Vol. 38, nr 3
• Strony: 49--66
• Opis fizyczny: Bibliogr. 19 poz., tab., rys.

Twórcy

autor

Obrzud R. F.

• Geotechnical computer consultant, Karakas & Français, Switzerland

autor

Hartmann S.

• École Polytechnique Fédérale de Lausanne, Switzerland

autor

Podleś K.

• Cracow University of Technology

Bibliografia

• [1] ZSoil manual, Elmepress and Zace Services Limited, Lausanne, Switzerland 2014.
• [2] EN 1992-1-1 (2002): Eurocode 0: Basis of structural design. The European Union Per Regulation 305/2011, Directive 98/34/EC, Directive 2004/18/EC.
• [3] EN 1992-1-1 (2004): Eurocode 2: Design of concrete structures – Part 1-1: General rules and rules for buildings. The European Union Per Regulation 305/2011, Directive 98/34/EC, Directive 2004/18/EC.
• [4] AUBRY D., OZANAM O., Free-surface tracking through non- saturated models, [in:] Swoboda (ed.), Numerical Methods in Geomechanics, Balkema, Innsbruck, 1988, 757–763.
• [5] BENZ T., Small–strain stiffness of soils and its numerical consequences, PhD thesis, University of Stuttgart 2006.
• [6] BURLAND J.B., SIMPSON B., ST JOHN H.D., Movements around excavations in London Clay, Proc. 7th ECSMFE, Brighton 1979, Vol. 1, 13–29.
• [7] BURLAND J.B., Small is beautiful – the stiffness of soils at small strains, 9th Bjerrum Memorial Lecture, Canadian Geotechnical Journal, 1989, Vol. 26, 499–516.
• [8] DYVIK R., MADSHUS C., Laboratory measurements of Gmax using bender elements, Norwegian Geotechnical Institute, Oslo, Norway, 1985, Publication No. 161, 186–196.
• [9] IRMAY S., On the hydraulic conductivity of unsaturated soils, Trans. Am. Geophys. Union, 1956, 35, 463–468.
• [10] JARDINE R.J., POTTS D.M., FOURIE A.B., BOURLAND J.B., Studies of the influence of non-linear stress-strain characteristics in soi-structure interaction, Géotechnique, 1986, Vol. 36, No. 3, 377–396.
• [11] OBRZUD R., TRUTY A., The hardening soil model- a practical guidebook, edition 2016, Technical Report Z Soil. PC 100701, Zace Services Ltd. 2011.
• [12] SCHANZ T., Zur Modellierung des mechanischen Verhaltens von Reinbungsmaterialien, Mitt. Inst. für Geotechnik 45. Universitat Stuttgart 1998.
• [13] SCHANZ T., VERMEER P., BONIER P., Formulation and verification of the Hardening Soil Model, [in:] Beyond 2000 in Computational Geotechnics, Balkema, Rotterdam 1999.
• [14] SCHWEIGER H.F., Benchmarking in Geotechnics, CGG- IR006-2002, Graz University of Technology, Austria 2002.
• [15] TRUTY A., On certain classes of mixed and stabilized mixedfinite element formulations for single and two-phase geoma- terials, Zeszyty Naukowe Politechniki Krakowskiej, Seria Inżynieria Środowiska 48, Kraków 2002.
• [16] TRUTY A., ZIMMERMANN T., Stabilized mixed finite element formulations for materially nonlinear partially saturated two-phase media, Computer Methods in Applied Mechanics and Engineering, 2006, 195, 1517–1546.
• [17] TRUTY A., Hardening Soil model with small strain stiffness, Technical Report Z Soil.PC 080901, Zace Services Ltd 2009.
• [18] TRUTY A., OBRZUD R.F., Improved formulation of the Hardening Soil model in the context of modelling the undrained behaviour of cohesive soils, Studia Geotechnica et Mechan- ica, 2015, Vol. 37, No. 2.
• [19] VAN GENUCHTEN M.T., A closed form equation for predicting the hydraulic conductivity of unsaturated soils, Soil Sciences Am. Soc., 1980, 44, 892–898.

Uwagi

PL

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017).