Class A predictions of a NATM tunnel in stiff clay

Svoboda, T; Maš́ın, David; Boháč, Jan

doi:10.1016/j.compgeo.2010.07.003

Cited by 25 publications

(15 citation statements)

References 20 publications

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“…The degradation of stiffness with small strain should be considered when analysing deformation problems. Otherwise, the soil-structure interaction computation may be misleading (Jardine et al 1986;Addenbrooke et al 1997;Hejazi et al 2008;Mašín 2009;Svoboda et al 2010). …”

Section: Introductionmentioning

confidence: 97%

Ability of three different soil constitutive models to predict a tunnel’s response to basement excavation

Sun

Gan

et al. 2015

Can. Geotech. J.

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Many constitutive models are available nowadays to predict soil-structure interaction problems. It is sometimes not very easier for engineers to select a suitable soil model to carry out their design analyses in terms of complexity versus accuracy. This paper describes the application of three constitutive models to back-analyse a well-instrumented centrifuge model test, in which the effect of basement excavation on an existing tunnel was simulated. These three models include a linear elastic-perfectly plastic model with the Mohr-Coulomb failure criterion (called MC model), a nonlinear elastic Duncan-Chang model (DC) and a hypoplastic model (HP), the last of which can capture path-dependent and strain-dependent soil stiffness even at small strains. By comparing with measured data from the centrifuge model test, it is found that the HP model yielded the best predictions of tunnel heave among the three models. Not only the gradient but also the magnitude of tunnel heave is predicted well by this HP model. This can be explained by the fact that the HP model can capture the path-dependent and strain-dependent soil stiffness even at small strains but not the MC and DC models. However, all three models underestimated the change in tunnel diameter and the maximum tensile bending strain in the transverse direction.

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Section: Introductionmentioning

confidence: 97%

Ability of three different soil constitutive models to predict a tunnel’s response to basement excavation

Sun

Gan

et al. 2015

Can. Geotech. J.

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“…The full 3D numerical model of the exploratory adit has been developed by Svoboda et al [53]. The parameters of the hypoplastic model for clays were calibrated on the basis of quality laboratory experiments that included measurements of small strain stiffness characteristics using local LVDT strain transducers and bender elements.…”

Section: Fig 7 Finite Element Mesh Used In the Analyses Of The Explmentioning

confidence: 99%

“…Two cases were considered in the analyses, one with original model parameters calibrated on the basis of laboratory experiments, and the second with parameters optimised based on monitoring results from the exploratory adit (see [53] for details). Only simulations with the original parameter set are considered in this paper, so that direct comparison with simulations of the exploratory adit is possible.…”

Section: Dobrovskeho Tunnelmentioning

confidence: 99%

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Comparison of displacement field predicted by 2D and 3D finite element modelling of shallow NATM tunnels in clays

Svoboda

Maš́ın

2011

Geotechnik

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The 2D load-reduction method for simulating NATM tunnels using plane strain finite elements is evaluated in the paper by comparison with fully 3D simulations. Three real shallow tunnels in urban environment in different stiff clays were simulated. The soil behaviour was described by an advanced non-linear soil constitutive model based on the hypoplasticity theory. Time-dependent behaviour of shotcrete lining was considered in 3D simulations, whereas constant final stiffness was used in the plane strain analyses. The 2D analyses were thus controlled by a single parameter that accounts for 3D effects. It is shown that for an optimum value of this parameter, the displacement field predicted by the 2D method agrees well with the 3D simulations. In some cases only, a discrepancy was observed in the close vicinity of the tunnel. The controlling parameter was, however, found to be dependent on the problem simulated (for the same material) and also on the material properties (for the same tunnelling problem). Considering the material properties, the shear modulus at very small strain was found to be more influential than the shear modulus at large strain. The initial K 0 stress state did not influence the controlling parameter substantially. Vergleich der Prognose des Verschiebungsfeldes durch 2D-und 3D-FE-Modellierungen von seichten Tunneln im TonDie mit finiten Elementen mit ebenem Spannungszustand arbeitende 2D-Lastreduktionsmethode zur Simulierung von NÖT-Tunneln wird im vorliegenden Aufsatz im Vergleich zu vollen 3D-Simulationen bewertet. Es wurden drei existierende oberflächen-nahe Stadttunnel in verschieden festen Tonböden simuliert. Das Bodenverhalten wurde durch ein komplexes, nicht-lineares Bodenmodell auf Basis der Hypoplastizitätstheorie beschrieben. In den 3D-Simulationen wurde das zeitabhängige Verhalten der Spritzbetonauskleidung untersucht, wohingegen in den Analysen der ebenen Spannungszustände die konstante, endgültige Festigkeit des Betons verwendet wurde. Die 2D-Analysen wurden auf diese Weise durch einen einzelnen Parameter bestimmt, der den 3D-Wirkungen Rechnung trägt. Die Untersuchung zeigt, dass für einen Optimalwert dieses Parameters das mittels der 2D-Methode prognostizierte Verschiebungsfeld weitestgehend mit den 3D-Simulationen übereinstimmt. Nur in einigen Fällen war in unmittelbarer Nähe zum Tunnel eine Diskrepanz zu beobachten. Es wurde jedoch festgestellt, dass der bestimmende Parameter von der Art des simulierten Problems abhängt (für dasselbe Material) und auch von den Materialeigenschaften (für dasselbe Tunnelbauproblem). Für die Materialeigenschaften wurde festgestellt, dass der Schubmodul bei sehr kleinen Spannungen eine größere Rolle spielt als bei großen Spannungen. Der anfängliche K 0 -Lastzustand hatte keinen wesentlichen Einfluss auf den bestimmenden Parameter. Introduction3D numerical analysis is becoming an increasingly affordable tool for predicting deformation and stress redistribution induced by tunnelling. As tunnel excavation is clearly a three dimensional problem, conside...

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“…For the correct use it is thus the designer's responsibility to properly account for the range of stress to which the soil will be subjected. Application of different moduli for primary loading and unloading, their dependence on the actual stress level or extension to small strain theory may provide further improvements which together with its Svoboda et al, 2010;Kadlíček et al, 2015) including the present contribution, which is organized as follows. Following the introductory part attention is accorded to a brief description of basic features of the HC model in Section 2.…”

Section: Introductionmentioning

confidence: 99%

Applying hypoplastic model for soft soils to the analysis of anchored sheeting wall

Kadlíček¹

2015

Acta Geodynamica Et Geomaterialia

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This paper is concerned with a practical application of the hypoplastic constitutive model for soft soils. In particular, two specific implementations, so called standard and the one based on smallstrain theory, are considered and the resulting predictions are compared with those provided by the Mohr-Coulomb model. As an example, we considered an anchored underground wall built during the construction of extension of the line A of Prague's subway. The results of all numerical simulations obtained with the help of Geo5 FEM software were also compared with in situ measurements with attention devoted mainly to the evolution of deformation of the underground wall and of pre-stress forces of rope anchors. It is shown that extended formulation of the hypoplastic model accounting for high stiffness of soil at very small strains should be adopted to arrive at reliable and meaningful predictions of the soil response. ARTICLE INFO

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Class A predictions of a NATM tunnel in stiff clay

Cited by 25 publications

References 20 publications

Ability of three different soil constitutive models to predict a tunnel’s response to basement excavation

Ability of three different soil constitutive models to predict a tunnel’s response to basement excavation

Comparison of displacement field predicted by 2D and 3D finite element modelling of shallow NATM tunnels in clays

Applying hypoplastic model for soft soils to the analysis of anchored sheeting wall

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