Modelling of viscous effects in natural clays

Clarke, Steve; Hird, C. C.

doi:10.1139/t11-084

Cited by 9 publications

(4 citation statements)

References 29 publications

(65 reference statements)

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“…Different versions of the Brick-type model are reported in the literature giving satisfactory results in various FE computations, e.g. [19][20][21]. The Brick algorithm used in the calculations presented in this paper adheres to the implementation details published in [22].…”

Section: Stiffness Strain Degradationmentioning

confidence: 99%

Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation

2023

Archives of Civil Engineering

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In this paper, the problem of deformation induced by an open pit excavation in anisotropic stiff soils is analysed by FE modelling. The presented research is focused on the influence of material model with anisotropic stiffness on the accuracy of deformation predictions as compared with the field measurements. A new hyperelastic-plastic model is applied to simulate anisotropic mechanical behaviour of stiff soils. It is capable to reproduce mixed variable stress-induced anisotropy and constant inherent cross-anisotropy of the small strain stiffness. The degradation of stiffness depending on strain is modelled with the Brick-type model. The model formulation and parameters are briefly presented. General deformation pattern obtained in the exemplary 2D boundary value problem of an open pit excavation is investigated considering different values of inherent cross-anisotropy coefficient of small strain stiffness. The numerical simulations are performed as a coupled deformation-flow analysis which allows to properly model the drainage conditions. The excavation phases are simulated by removal of soil layers according to the realistic time schedule. Finally, the monitored case of the trial open pit excavation in heavily overconsolidated Oxford Clay at Elstow, UK is simulated with proposed material model both in 2D and 3D conditions. The obtained calculation results are compared with displacement measurements and discussed.

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Section: Stiffness Strain Degradationmentioning

confidence: 99%

Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation

2023

Archives of Civil Engineering

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“…Different versions of the BRICK model are reported in the literature giving satisfactory results in various FE computations, e.g. [9,11,14,23,25,40,43]. The original BRICK model [38] has been developed in plane strain for which volumetric strain and shear strain are appropriate axes-the sides of the room where the described pulling process takes place.…”

Section: Hs-brick Formulationmentioning

confidence: 99%

“…After unloading to point 14, the reloading back to the initial reversal at r a ¼ 180 kPa and overloading up to r a ¼ 185 kPa is simulated. In the desired hysteretic behaviour, the last reloading from point 14 should pass through old reversals (subsequently points 13,11,9,7,5,3,1) which is fulfilled only in the case of the new HS-Brick model. In the HSS model, the main hysteresis loop is not closed and point 15 is reached due to overshooting.…”

Section: Triaxial Hysteretic Behaviourmentioning

confidence: 99%

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Refinement of the Hardening Soil model within the small strain range

Cudny

Truty

2020

Acta Geotech.

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The popularity of the elasto-plastic Hardening Soil (HS) model is based on simple parameter identification from standard testing and empirical formulas. The HS model is implemented in many commercial FE codes designed to analyse geotechnical problems. In its basic version, the stress-strain behaviour within the elastic range is subject to the hypoelastic power law, which assures the barotropy of the elastic stiffness. However, a proper modelling within the small strain range, i.e. strain-induced stiffness degradation and correct reproduction of the hysteretic behaviour, was one of the most important drawbacks in the HS formulation. The first small strain stiffness extension to the HS model was proposed by Benz (Small strain stiffness of soils and its numerical consequences, 2007), and the new model was called Hardening Soil Small (HSS). Despite the simple isotropic formulation, its applicability was proved in various numerical simulations in geotechnics. However, the HSS formulation exhibits a serious fault known in the literature as overshooting, i.e. uncontrolled reset of the loading memory after tiny unloading-reloading cycles. The authors' main aim was to retain the set of material parameters for the HSS formulation and to propose a new small strain extension to the HS model without overshooting. The new proposal is based on the BRICK model which represents the concept of nested yield surfaces in strain space. The implementation aspects of the new HS-Brick model are described, and its performance is presented in some element tests and selected boundary value problems by comparisons with the HSS formulation.

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