NGI‐ADP: Anisotropic shear strength model for clay

Grimstad, Gustav; Andresen, Lars; Jostad, Hans Petter

doi:10.1002/nag.1016

Cited by 90 publications

(31 citation statements)

References 15 publications

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“…The strength dependence on the angle of inclination is, qualitatively, similar to previously reported experimental results (see, eg, Potts and Zdravkovic). This type of variation is predicted by other relevant clay models including the NGI‐ADP and MIT‐E3 models.…”

Section: Failure Criterionsupporting

confidence: 57%

“…The characteristic of unequal shear strengths in triaxial compression and extension is often referred to as “anisotropy” (for example, Prashant, Karlsrud et al, and Ladd). This is rather unfortunate as unequal compression and extension strengths are inherent feature of ideal isotropic Mohr‐Coulomb materials, cf., the previous section.…”

Section: Failure Criterionmentioning

confidence: 99%

“…In the following, a model incorporating cross‐anisotropic strength, stemming for example from a preferential direction of deposition, is considered. Identifying the normal to the plane of anisotropy (the direction of deposition) as the z ‐direction, the strength anisotropy may, following Grimstad et al, be accommodated by an appropriate shift of the yield surface. In the case where all shear stresses are zero, the geometric interpretation is a shift of the generalized Tresca surface in the direction of the σ z axis (see Figure ).…”

Section: Failure Criterionmentioning

confidence: 99%

“…In the general case, the relevant anisotropic version of the generalized Tresca model may be written as (again following Grimstad et al and using standard continuum mechanics sign conventions):

F_{u} = \overset{q}{true} - \frac{6 k}{\sqrt{3} false(1 + 1 false/ ρ false) \cos \overset{θ}{true} - 3 false(1 - 1 false/ ρ false) \sin \overset{θ}{true}},

where

\overset{q}{true} = \sqrt{3 Ĵ_{2}}

Ĵ_{2} = \frac{1}{2} {\overset{s}{true}}^{T} bold-italicD \overset{s}{true}

\overset{s}{true} = boldσ - bold-italicm p - a k bold-italicr

bold-italicm = {false(1, 1, 1, 0, 0, 0 false)}^{T}

bold-italicD = diag false(1, 1, 1, 2, 2, 2 false)

p = \frac{1}{3} m^{T} boldσ

bold-italicr = {((), \frac{1}{3}, \frac{1}{3}, - \frac{2}{3}, 0, 0, 0)}^{T}

\overset{θ}{true} = \frac{1}{3} \arcsin ((), \frac{3 \sqrt{3}}{2})

…”

Section: Failure Criterionmentioning

confidence: 99%

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AUS: Anisotropic undrained shear strength model for clays

Krabbenhøft

Galindo‐Torres

Xue

et al. 2019

Num Anal Meth Geomechanics

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Summary A total stress model applicable to clays under undrained conditions is presented. The model involves three strength parameters: the undrained shear strengths in triaxial compression, triaxial extension, and simple shear. The amount of physical anisotropy implied by the model is a function of the relative magnitude of these three strengths assuming a Mises‐type plastic potential. Elastoplastic deformation characteristics below failure are accounted for by a hardening law requiring two additional parameters that can be related to the axial strains halfway to failure in triaxial compression and extension. Finally, elasticity is accounted for by Hooke law. The result is a relatively simple model whose parameters can all be inferred directly from a combination of in situ and standard undrained laboratory tests. The model is applied to a problem involving the horizontal loading of a monopile foundation for which full scale tests have been previously conducted. The model shows good agreement with the measured data.

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Section: Failure Criterionsupporting

confidence: 57%

Section: Failure Criterionmentioning

confidence: 99%

Section: Failure Criterionmentioning

confidence: 99%

“…In the general case, the relevant anisotropic version of the generalized Tresca model may be written as (again following Grimstad et al and using standard continuum mechanics sign conventions):

F_{u} = \overset{q}{true} - \frac{6 k}{\sqrt{3} false(1 + 1 false/ ρ false) \cos \overset{θ}{true} - 3 false(1 - 1 false/ ρ false) \sin \overset{θ}{true}},

where

\overset{q}{true} = \sqrt{3 Ĵ_{2}}

Ĵ_{2} = \frac{1}{2} {\overset{s}{true}}^{T} bold-italicD \overset{s}{true}

\overset{s}{true} = boldσ - bold-italicm p - a k bold-italicr

bold-italicm = {false(1, 1, 1, 0, 0, 0 false)}^{T}

bold-italicD = diag false(1, 1, 1, 2, 2, 2 false)

p = \frac{1}{3} m^{T} boldσ

bold-italicr = {((), \frac{1}{3}, \frac{1}{3}, - \frac{2}{3}, 0, 0, 0)}^{T}

\overset{θ}{true} = \frac{1}{3} \arcsin ((), \frac{3 \sqrt{3}}{2})

…”

Section: Failure Criterionmentioning

confidence: 99%

See 2 more Smart Citations

AUS: Anisotropic undrained shear strength model for clays

Krabbenhøft

Galindo‐Torres

Xue

et al. 2019

Num Anal Meth Geomechanics

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“…The main reason for using HVMCap for capacity calculations was to benefit from the computational speed and cover a larger variety of conditions. In both programs, the NGI-ADP model (Grimstad et al, 2012) has been used for modelling the soil. The NGI-ADP model assumes undrained incompressible soil and has an anisotropic shear strength failure criterion.…”

Section: Finite-element Models and Analysesmentioning

confidence: 99%

A numerical study of capacity and stiffness of circular skirted foundations in clay subjected to combined static and cyclic general loading

2018

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Skirted foundations have been widely applied as offshore foundations for several decades. In design, the use of failure envelopes is convenient for assessing stability under combined loading. A large number of studies on failure envelopes exist in the literature based on experiments and numerical analyses. Most of these studies focus on ultimate capacity and static loading. This paper presents a numerical study focusing on cyclic degradation and failure envelopes for skirted foundations subjected to combined cyclic and static loading. It was found that the shapes of the failure envelopes are little affected by degradation expressed by the number of equivalent cycles. In addition to failure envelopes, contours of displacements were computed in the three-dimensional load space (vertical, horizontal and moment load) for a more complete description of the response. As an example, the well-defined cyclic contour diagrams of Drammen clay were utilised to demonstrate how foundation response diagrams can be established. The database is accompanied by a simplified procedure to account for cyclic degradation through equivalent number of cycles, different normalised load-displacement response and variation in foundation geometry. The framework of procedures can be used to estimate foundation stiffness and capacity and the results can serve as a basis for the development of foundation macro-element models.

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Numerical Modeling for Geotechnical Design

Wang

2018

Encyclopedia of Maritime and Offshore Engineering

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Although the limit equilibrium methods and mixed empirical–numerical methods are widely used in routine design of offshore geotechnical engineering, the finite element (FE) approaches have become the routine “calculator” for greater challenges. The key questions of FE modeling are discussed, including (i) the soil models in terms of monotonic and cyclic loadings; (ii) drained, undrained, or partially drained conditions; (iii) the influence of inertia; and (iv) the selection between small strain and large deformation analyses. Popular commercial FE programs and several typical offshore applications are addressed as well.

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NGI‐ADP: Anisotropic shear strength model for clay

Cited by 90 publications

References 15 publications

AUS: Anisotropic undrained shear strength model for clays

AUS: Anisotropic undrained shear strength model for clays

A numerical study of capacity and stiffness of circular skirted foundations in clay subjected to combined static and cyclic general loading

Numerical Modeling for Geotechnical Design

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