The soilmodels.info project

Gudehus, G.; Amorosi, A.; Gens, Antonio; Herle, Ivo; Kolymbas, Dimitrios; Maš́ın, David; Wood, David Muir; Niemunis, Andrzej; Nova, Roberto; Pastor, Manuel; Tamagnini, Claudio; Viggiani, Gioacchino

doi:10.1002/nag.675

Cited by 125 publications

(56 citation statements)

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“…The model proposed by Von Wolffersdorff (1996) was adopted to describe the behaviour of Toyoura sand. This model was incorporated into the software package ABAQUS using opensource implementation which can be freely downloaded from the web (Gudehus et al 2008).…”

Section: The Hypoplastic Modelmentioning

confidence: 99%

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: The Hypoplastic Modelmentioning

confidence: 99%

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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“…This model has been shown to represent accurately the soil behaviour from the very small strain range to large strain range, including high quasielastic stiffness in the very small strain range and its non-linear decrease with increasing strain level [21] [22] [37]. A finite element implementation of this model is freely available on the web [20]. The basic version of the hypoplastic model requires five parameters, whose physical interpretation corresponds to the parameters of the Modified Cam-Clay model [50]: N, λ * , κ * , ϕ c and r. The parameters N and λ * define the position and the slope of the isotropic normal compression line (NCL) within the ln p vs. ln (1 + e) representation, where p is the effective mean stress and e is the void ratio.…”

Section: D Simulations Of Case Studies Analysedmentioning

confidence: 99%

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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“…The subroutine UMAT allows to use particular constitutive models in finite element codes such as ABAQUS or PLAXIS. The UMAT for the following models are available on the webpage soilmodels.info. The hypoplastic model for sand by von Wolffersdorff with and without intergranular strain concept, and The hypoplastic model for undisturbed and remoulded clays by Mašín with and without intergranular strain concept. …”

Section: Availability Of Umatmentioning

confidence: 99%

Genealogy of hypoplasticity and barodesy

Kolymbas

Medicus

2016

Num Anal Meth Geomechanics

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SUMMARYThis article is an attempt at providing an insight into the development of hypoplasticity (including barodesy, which is a recent development of hypoplasticity) as a theory elaborated since 1977, when the first version was published by the first author, until present. The multiplicity of the many versions published since then is hard to overlook. This article presents a review and insight into the evolution of a theory and the struggle to formulate a satisfactory constitutive law. Among the many proposed versions, we focus on those ones that can be seen as changes of paradigm. Copyright © 2016 John Wiley & Sons, Ltd. ON THE DIVERSITY OF CONSTITUTIVE MODELSA constitutive law (or 'constitutive relation' or 'constitutive model') is a theory that describes the mechanical behaviour of a material or class of materials, in our case, soil (and other granular materials). Some scientific communities use the alternative term 'closure equation', as a constitutive equation provides the missing link that is needed next to the balance laws of physics to solve a boundary value problem. Being a theory, a constitutive law is virtually an assumption that can be used as long as it has not been disproved. It is, however, not so straightforward to judge upon falsification of a theory. In the realm of physics, mechanics and, in our case, soil mechanics, theories have always a limited range of validity. Thus, the question whether a particular experimental outcome discredits a theory or not can also be considered as the question whether this outcome falls within the range of validity of the considered theory. Moreover, there is always a deviation between theoretical predictions and experimental outcomes. It is often a subjective judgement whether a deviation is considered as small or large. For these reasons, a constitutive law cannot be simply rated as 'right' or 'wrong', there are many nuances between these attributes. In case a constitutive law provides a prediction judged as non-satisfactory, the question arises whether the shortage can be removed by a modification or it is due to an inherent conceptual failure of the underlying theory. Thus, theories can be either modified or abandoned and replaced by completely new ones.The emergence of a new version not only signifies an improvement but also blames the precedent version for inadequacy. It underlines thus the feeling that a constitutive relation does not mirror a permanent truth. Similar mixed feelings are evoked whenever a new operational system is launched for our computer: the expectation of improved performance is counterbalanced by the displeasure for the necessary rearrangements. In the end, we should realize that perfection is achievable neither for operational systems nor for constitutive relations. The possibility of modifications proves, however, that a given system or theory can still be useful.It should be mentioned that we have refrained from assessing each version by mentioning its advantages and disadvantages, as this would render the paper overly long and is ...

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The soilmodels.info project

Cited by 125 publications

References 0 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

Genealogy of hypoplasticity and barodesy

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