New Rheological Model for Soil Behavior

Komamura, Fujiya; Huang, R. J.

doi:10.1061/ajgeb6.0000068

Cited by 27 publications

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“…The material was a Mississippi Buckshot clay with a water content close to its plastic limit. It may be seen that its behaviour is consistent with the trends established by Komamura and Huang (1974). However, further works have shown that some clays may have a visco-elasto-plastic behaviour with water content above their liquid limit Figure 2.6: Effect of strain rate on undrained shear stress obtained using torsional hollow cylinder (after Cheng 1981).…”

Section: Constitutive Lawssupporting

confidence: 65%

“…When viscous effects are studied in detail, it is found that for a particular soil (that is for a particular liquid limit w l ), the soil behaviour depends on the water content w, as shown in figure 2.5, from Komamura and Huang (1974). According to them, when w > w l the behaviour is viscous, that is, close to a newtonian fluid; whereas when w < w vp the behaviour is visco-elasto-plastic.…”

Section: Constitutive Lawsmentioning

confidence: 99%

“…The model is defined in terms of a shear stress-shear strain rate relationship, instead of a stress-strain one. The study of strain rate effects on soil behaviour has been considered in many works (Berre and Bjerrum 1973, Komamura and Huang 1974, Cheng 1981, Mesri, Febres-Cordero, Shields and Castro 1981, Leroueil, Kabbaj, Tavenas and Bouchard 1985. Some of them have proposed constitutive laws relating stresses with strains and strain rates to account for time influence, based on a visco-elasto-plastic theory.…”

Section: Constitutive Lawsmentioning

confidence: 99%

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Numerical modelling of complex geomechanical problems

Pérez Foguet

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La tesis se centra en el desarrollo de técnicas numéricas específicas para la resolución de problemas de mecánica de sólidos, tomando como referencia aquellos que involucran geomateriales (suelos, rocas, materiales granulares,...). Concretamente, se tratan los siguientes puntos: 1) formulaciones Arbitrariamente Lagrangianas Eulerianas (ALE) para problemas con grandes desplazamientos del contorno; 2) métodos de resolución para problemas no lineales en el campo de la mecánica de sólidos y 3) modelización del comportamiento mecánico de materiales granulares mediante leyes constitutivas elastoplásticas. Las principales aportaciones de la tesis son: el desarrollo de una formulación ALE para modelos hyperelastoplásticos y el cálculo de operadores tangentes para distintas leyes constitutivas y esquemas de integración temporal no triviales (uso de esquemas de derivación numérica, técnicas de subincrementación y modelos elastoplásticos con endurecimiento y/o reblandecimiento dependientes del trabajo plástico o la densidad). Se presentan diversas aplicaciones que muestran las principales características de los desarrollos presentados (análisis del ensayo del molinete para arcillas blandas, del ensayo triaxial para arenas, de la rotura bajo una cimentación, del proceso de estricción de una barra metálica circular y de un proceso de estampación en frío), dedicando una especial atención a los aspectos computacionales de la resolución de dichos problemas. Por último, se dedica un capítulo específico a la modelización y la simulación numérica de procesos de compactación fría de polvos metálicos y cerámicos. Numerical modelling of problems involving geomaterials (i.e. soils, rocks, concrete and ceramics) has been an area of active research over the past few decades. This fact is probably due to three main causes: the increasing interest of predicting the material behaviour in practical engineering situations, the great change of computer capabilities and resources, and the growing interaction between computational mechanics, applied mathematics and different engineering fields (concrete, soil mechanics...). This thesis fits within this last multidisciplinary approach. Based on constitutive modelling and applied mathematics and using both languages the numerical simulation of some complex geomechanical problems has been studied. The state of the art regarding experiments, constitutive modelling, and numerical simulations involving geomaterials is very extensive. The thesis focuses in three of the most important and actual ongoing research topics within this framework: 1) the treatment of large boundary displacements by means of Arbitrary Lagrangian-Eulerian (ALE) formulations; 2) the numerical solution of highly nonlinear systems of equations in solid mechanics; and 3) the constitutive modelling of the nonlinear mechanical behaviour of granular materials. The three topics have been analysed and different contributions for each one of them have been developed. Moreover, some of the new developments have been applied to the numerical modelling of cold compaction processes of powders. The process consists in transforming a loose powder into a compacted sample through a large volume reduction. This problem has been chosen as a reference application of the thesis because it involves large boundary displacements, finite deformations and highly nonlinear material behaviour. Therefore, it is a challenging geomechanical problem from a numerical modelling point of view. The most relevant contributions of the thesis are the following: 1) with respect to the treatment of large boundary displacements: quasistatic and dynamic analyses of the vane test for soft materials using a fluid-based ALE formulation and different non-newtonian constitutive laws, and the development of a solid-based ALE formulation for finite strain hyperelastic-plastic models, with applications to isochoric and non-isochoric cases; 2) referent to the solution of nonlinear systems of equations in solid mechanics: the use of simple and robust numerical differentiation schemes for the computation of tangent operators, including examples with several non-trivial elastoplastic constitutive laws, and the development of consistent tangent operators for different substepping time-integration rules, with the application to an adaptive time-integration scheme; and 3) in the field of constitutive modelling of granular materials: the efficient numerical modelling of different problems involving elastoplastic models, including work hardening-softening models for small strain problems and density-dependent hyperelastic-plastic models in a large strain context, and robust and accurate simulations of several powder compaction processes, with detailed analysis of spatial density distributions and verification of the mass conservation principle.

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Section: Constitutive Lawssupporting

confidence: 65%

Section: Constitutive Lawsmentioning

confidence: 99%

Section: Constitutive Lawsmentioning

confidence: 99%

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Numerical modelling of complex geomechanical problems

Pérez Foguet

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“…The displacement under constant stress conditions is recognized as creep deformation and modelled as time-dependent deformation. Christensen and Wu 10 , Murayama and Shibata 11 , Komamura and Huang 12 and Ter-Stepanian 13 developed a rheological model to explain the creeping shear behaviour of clayey soil. Sekiguchi and Ohta 14 , Adachi and Oka 15 , Desai et al 16 , Wheeler et al 17 , Dafalias et al 18 , and Leoni et al 19 proposed elasto-viscoplastic models to simulate time-dependent shear deformation under anisotropic conditions.…”

Section: Introductionmentioning

confidence: 99%

Development of the shear displacement of sandy soil due to absorption under constant shear stress for creep failure

Sasahara

2022

Sci Rep

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Measurement of the displacement and pore pressure in physical model slopes and natural slopes revealed that not only an accelerative increase up to failure but also a decelerative increase occurred in surface displacement under a constant groundwater level, which could be recognized as creep deformation under constant stress. The displacement increased significantly at first in both types, which made it difficult to evaluate whether the displacement developed to the point of failure at the start of the increase. It was necessary to find an indicator for evaluation as the first step of the prediction of an onset of slope failure. Measurement of shear and normal displacements of the sandy specimen in an inclined direct shear box with increasing water content was conducted to examine the indicator. The increase in the shear displacement was categorized into three types: the accelerative increase up to failure with increasing volumetric water content (VWC), the accelerative increase up to failure under constant VWC just prior to failure, and the decelerative increase under constant VWC. It was recognized that a constant VWC corresponded to constant suction from the experimental data. Shear displacement increased up to failure with the monotonic decrease in void ratio just prior to failure in the case of increasing VWC. The void ratio monotonically decreased under constant VWC in the case of shear displacement termination under constant VWC, while it significantly varied at first and then converged to a constant value just prior to failure in the case of shear displacement increase with constant VWC. The ultimate void ratio under the same stress conditions might have been unique. These facts revealed that the void ratio can be recognized as an indicator of the failure of specimens under creep deformation according to absorption. When the void ratio converges to a constant value under constant VWC, the shear displacement might increase up to failure, while the void ratio varying under constant VWC indicates that the shear displacement terminates before failure.

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Visco-elastic load transfer models for axially loaded piles

Guo

2000

Int. J. Numer. Anal. Meth. Geomech.

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SUMMARYViscoelastic or creep behaviour can have a signi"cant in#uence on the load transfer (t}z) response at the pile}soil interface, and thus on the pile load settlement relationship. Many experimental and theoretical models for pile load transfer behaviour have been presented. However, none of these has led to a closed-form expression which captures both non-linearity and viscoelastic behaviour of the soil. In this paper, non-linear viscoelastic shaft and base load transfer (t}z) models are presented, based on integration of a generalized viscoelastic stress}strain model for the soil. The resulting shaft model is veri"ed through published "eld and laboratory test data. With these models, the previous closed-form solutions evolved for a pile in a nonhomogeneous media have been readily extended to account for visco-elastic response. For 1-step loading case, the closed-form predictions have been veri"ed extensively with previous more rigorous numerical analysis, and with the new GASPILE program analysis. Parametric studies on two kinds of commonly encountered loading: step loading, ramp (linear increase followed by sustained) loading have been performed. Two examples of the prediction of the e!ects of creep on the load settlement relationship by the solutions and the program GASPILE, have been presented.

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New Rheological Model for Soil Behavior

Cited by 27 publications

References 0 publications

Numerical modelling of complex geomechanical problems

Numerical modelling of complex geomechanical problems

Development of the shear displacement of sandy soil due to absorption under constant shear stress for creep failure

Visco-elastic load transfer models for axially loaded piles

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