Comparison and Study on Constitutive Models for Coarse Grained Materials under Different Stress Path

2010 ◽  
Author(s):  
Sheng Zhu ◽  
Yongming Wang ◽  
Shurong Feng ◽  
Chunxin Zhong
Keyword(s):  
Constitutive Models ◽  
Stress Path ◽  
Coarse Grained ◽  
Comparison And Study

scholarly journals Investigation of Lade-Kim Plastic Potential Applicability under Various Stress Paths for Rockfill Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Liping Chen ◽  
Shihai Bian ◽  
Xiaokai Niu ◽  
Yongbo Zhao
Keyword(s):  
Path Dependence ◽  
Stress Path ◽  
Constant Stress ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Stress Increment ◽  
Verification Method ◽  
Rockfill Materials ◽  
Plastic Potential ◽  
Increment Ratio

The dilatancy behavior of rockfill materials shows obvious stress path dependence. Lade-Kim plastic potential equation has been proposed for a long time to model the mechanical behavior of sand and concrete materials. However, it lacks the verification of rockfill materials, especially under various stress paths. In this paper, the dilatancy performance of coarse-grained materials under various stress paths is investigated, and then the dilatancy equation description and verification method based on Lade-Kim plastic potential are given. The applicability of Lade-Kim plastic potential for different stress path tests, such as conventional triaxial tests, constant P tests, and constant stress (increment) ratio tests, are verified and evaluated. It is found that Lade-Kim plastic potential is difficult to consider the influence of stress path. Finally, the Lade-Kim plastic potential, together with nonlinear dilatancy equation, is evaluated by changing the dilatancy equation in the framework of generalized plasticity. Lade-Kim plastic potential is suitable for constant stress increment ratio loading experiments and special care should be taken when applied to other stress paths. These works are helpful to understand stress path dependence of dilatancy behavior for rockfill materials and is beneficial for the establishment of stress path constitutive model.

Upgrading Equipment and Procedures for Stress Path Triaxial Testing of Coarse-Grained Materials

1997 ◽  
Vol 20 (4) ◽  
pp. 459 ◽  
Author(s):  
RC Chaney ◽  
KR Demars ◽  
A Flora ◽  
G Modoni
Keyword(s):  
Stress Path ◽  
Coarse Grained ◽  
Triaxial Testing

Research on the Proper Selection of Soil Constitutive Relation in Modeling Underground Excavation

2008 ◽  
Vol 575-578 ◽  
pp. 1358-1363
Author(s):  
Yin Tao Zhang ◽  
Lian Jin Tao ◽  
Si Hai Tang ◽  
Bin Sun
Keyword(s):  
Constitutive Relation ◽  
Stress Path ◽  
Coarse Grained ◽  
Elastic Response ◽  
Geological Condition ◽  
Underground Excavation ◽  
Lagrangian Analysis ◽  
Circular Tunnel ◽  
Modified Cam Clay ◽  
Selection Of

Soil is a complex material whose properties are elastic, plastic and viscious. The selection of a proper constitutive relation is important in the study of stratum movement induced by underground excavation in modern cities. First, based on the Fast Lagrangian Analysis of Continua (FLAC) method, the elastic response stress (p, q) distribution induced by a circular tunnel is analyzed, and the surrounding soil is divided into four categories: p increase q increase, p increase q decrease, p decrease q increase, p decrease q decrease according to p-q stress path. The character of p-q distribution and the plastic zone induced by tunneling in clay are compared when the Mohr-Coulomb model (M-C), the Drucker-Prager model (D-P) and the Modified Cam-Clay model (C-C) are adopted; the C-C model is considered to be suitable for simulating underground excavation problems. Second, factors such as stratum character, stress path and relative position between soil and excavation are thought to be important in the selection of a proper constitutive relation, accounting for the geological condition of Beijing and measuring techniques being used in geotechnical engineering. Fine grained soils such as clay and silt can be modeled by the C-C model. Coarse grained soil, for containing and not containing excavation, may be represented using the M-C model considering strain softening and the normal M-C model. Finally, with the aid of FLAC method and its internal language FISH, a scheme of estimating and controlling parameter input is suggested.

Simplified analyses of stress induced anisotropy in remolded soft clay under undrained conditions

2020 ◽  
Vol 2 (105) ◽  
pp. 56-64
Author(s):  
P. Lin ◽  
Z.-x. Li ◽  
A. Garg ◽  
J.S. Yadav
Keyword(s):  
Soft Clay ◽  
Constitutive Models ◽  
Stress Path ◽  
Complex Stress ◽  
Triaxial Tests ◽  
Induced Anisotropy ◽  
Stress Induced Anisotropy ◽  
Undrained Conditions ◽  
Plain Strain ◽  
Properties Of Soil

Purpose: The soil’s anisotropy induced by stress (i.e. stress induced anisotropy) has an important effect on the behavior of soil. This paper focuses on analyzing the anisotropy of remolded Shantou soft clay under compression stress path. Design/methodology/approach: Experiments were executed by using three axle experimental instruments. The data obtained from the plain strain tests were analyzed and the relationship between stress and strain was calculated by using the modified Duncan- Chang and Lade-Duncan models. The models were modified under the condition of plain strain and cohesion. Findings: It was concluded that in complex stress path conditions, the conventional triaxial tests may not fully reflect the actual stress of soil and its response in the Duncan-Chang and Lade-Duncan models. Research limitations/implications: The formulation of Mohr-Coulomb failure criterion in the plasticity framework is quite diffcult. As a result, dilatancy cannot be described. The properties of soil in unload or drained conditions remain to be part of further investigated. Practical implications: Based upon the two stiffness parameters, the modified Duncan- Chang model has captured the soil behaviour in a very conformable way and is recommened for practical modeling. These constitutive models of soil are widely used in the numerical analyses of soil structure such as embankments. Originality/value: Duncan-Chang and Lade-Duncan models widely used in engineering practices are modes based on conventional triaxial cases. Both models have have some inherent limitations to represent the stress-strain characteristics of soils, such as shear-induced dilatancy and stress path dependency and required corrections. In this investigation, the tests are carried out in undrained conditions. It is related to the properties of soil in load conditions.

scholarly journals Scientific Machine Learning for Coarse-Grained Constitutive Models

2020 ◽  
Vol 47 ◽  
pp. 693-695
Author(s):  
David González ◽  
Francisco Chinesta ◽  
Elías Cueto
Keyword(s):  
Machine Learning ◽  
Constitutive Models ◽  
Coarse Grained

Unified hardening (UH) model for overconsolidated unsaturated soils

2014 ◽  
Vol 51 (7) ◽  
pp. 810-821 ◽  
Author(s):  
Y.P. Yao ◽  
L. Niu ◽  
W.J. Cui
Keyword(s):  
Unsaturated Soils ◽  
Path Dependence ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Stress Path ◽  
Triaxial Tests ◽  
Additional Material ◽  
Basic Model ◽  
Proposed Model ◽  
Unsaturated Clays

Naturally deposited clays are often unsaturated and overconsolidated. Within the frameworks of the Barcelona Basic model (BBM) for normally consolidated unsaturated clays and the unified hardening (UH) model for overconsolidated saturated clays, a three-dimensional constitutive model for overconsolidated unsaturated clays is proposed in this paper. This model can be reduced to the original UH model for overconsolidated saturated clays when suction becomes zero and the BBM when the overconsolidated behaviour disappears. Compared with existing constitutive models for unsaturated clays, the influence of a high overconsolidation ratio (OCR) on wetting deformation can be adequately described. Also, many other characteristics of overconsolidated unsaturated clays can be modelled, including strain-hardening, softening, shear dilatancy, and stress path–dependence behaviour. Compared with the BBM, the proposed model requires no additional material parameter. The validity of the UH model for overconsolidated unsaturated clays has been confirmed by data from two groups of wetting tests performed by the authors and previous triaxial tests in the literature.

Creep Constitutive Models Suitable for Solder Alloys in Electronic Assemblies

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Subhasis Mukherjee ◽  
Mohammed Nuhi ◽  
Abhijit Dasgupta ◽  
Mohammad Modarres
Keyword(s):  
Creep Deformation ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Coarse Grained ◽  
Mechanistic Models ◽  
Creep Response ◽  
Test Conditions ◽  
Sn37pb Solder

Most solders used in electronic systems have low-melting temperature and hence experience significant amount of creep deformation throughout their life-cycle because typical operational and test conditions represent high homologous temperature. Phenomenological and mechanistic models used in the literature for predicting creep response of both bulk and grain scale specimens are reviewed in this paper. The phenomenological models reviewed in this paper are based on purely empirical observations of the creep deformation behavior or derived from qualitative interpretation of the underlying microscale mechanisms. These models have some intrinsic disadvantages since they do not have explicit mechanistic dependence on microstructural features. Therefore, the constitutive relations derived using the above models are difficult to extrapolate beyond the test conditions. This paper also reviews how some of the above limitations can be mitigated by using mechanistic or microstructurally motivated models. Mechanistic models are capable of estimating the material creep response based on the detailed physics of the underlying mechanisms and microstructure. The microstructure and constitutive response of the most popular family of lead-free solders, namely, SnAgCu (SAC) solders, are significantly different from those of previously used eutectic Sn37Pb solder. The creep deformation in Sn37Pb solder occurs primarily through diffusion-assisted grain-boundary sliding. In SAC solder joints, dislocation-based creep deformation mechanisms such as glide, climb, detachment, and cross-slip appear to be the dominant mechanisms in coarse-grained joints. Mechanistic creep models are therefore based on the deformation mechanisms listed above.

scholarly journals Experimental framework for evaluating the mechanical behavior of dry and wet crushable granular materials based on the particle breakage ratio

2015 ◽  
Vol 52 (5) ◽  
pp. 587-598 ◽  
Author(s):  
Carlos Ovalle ◽  
Christophe Dano ◽  
Pierre-Yves Hicher ◽  
Mónica Cisternas
Keyword(s):  
Mechanical Behavior ◽  
Water Content ◽  
Granular Materials ◽  
Mechanical Response ◽  
Empirical Relation ◽  
Initial Density ◽  
Constitutive Models ◽  
Stress Path ◽  
Particle Crushing ◽  
Effect Of Water

It has been widely shown that particle crushing increases the compressibility of granular materials. For a particular crushable material and given test conditions, an empirical relation can be established between the breakage ratio and the plastic work. Along these lines, constitutive models have been developed based on the effect of grading evolution during crushing. In parallel, due to corrosive attacks of the humid environment at the tip of microcracks within solid grains, the mechanical behavior of crushable granular materials depends also on the water content: the higher the material humidity, the higher the particle crushing. However, the experimental data on the relation between loading–wetting conditions and the breakage ratio are still quite scarce. In this paper, we present experimental results on crushable sand to study the effect of flooding under isotropic, oedometric, and triaxial stress paths. The main objective of this study is to obtain a consistent framework for the effect of water based on the breakage ratio. Our results have shown that, for a given initial density and stress path, the dry material after flooding reaches the equivalent behavior of the initially wetted material in terms of compression curve, particle crushing, and creep compressibility index, regardless of the point of flooding. Moreover, the relation between the breakage ratio and the final void ratio is unique and depends neither on the stress path, the water content, the point of flooding, nor the loading condition (time of creep or relaxation), but exclusively on the initial density and on intrinsic parameters. These findings could improve the prediction of the effect of water and time on the mechanical response of crushable granular materials through constitutive models based on grading evolution.

Unloading Triaxial Experimental Study on Stress Path of Excavated Soil Slope

2011 ◽  
Vol 243-249 ◽  
pp. 2797-2801 ◽  
Author(s):  
Yan Gang Zhang ◽  
Kun Yong Zhang ◽  
Wang Lin Li ◽  
Qiao Zhen Shi
Keyword(s):  
Principal Stress ◽  
Triaxial Compression ◽  
Constitutive Models ◽  
Confining Pressure ◽  
Stress Path ◽  
Soil Mass ◽  
Soil Slope ◽  
Compression Tests ◽  
Excavation Process ◽  
Major Principal Stress

The current research was implemented to study the practical unloading stress path that the slope mass experienced during the excavation process, which is very important in the stress and strain numerical analysis. Series of unloading tests were carried out under different confining pressure. During the test process, the minor principal stress was kept decreasing, while the major principal stress was kept unchanged to simulate the stress path in some locations of the soil slope, such as at the top of the slope. The corresponding conventional triaxial compression tests were also carried out as comparison. It is shown that there are many differences between the unloading and loading tests. Through analyzing, the tests results could be applied in the development of unloading constitutive models of excavation soil mass. Also, such unloading tests data are valuable in calibration and verification of the current existing popularly used models.

Geomechanical behaviour of gassy soils and implications for submarine slope stability: a literature analysis

2019 ◽  
Vol 500 (1) ◽  
pp. 277-288 ◽  
Author(s):  
P. Kaminski ◽  
M. Urlaub ◽  
J. Grabe ◽  
C. Berndt
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Large Scale ◽  
Pore Space ◽  
Constitutive Models ◽  
Coarse Grained ◽  
Extensive Literature ◽  
Slope Failures ◽  
Submarine Slope ◽  
Hydraulic Behaviour

AbstractSubmarine slope failures pose a direct threat to seafloor installations and coastal communities. Here, we evaluate the influence of free gas on the soil's shear strength and submarine slope failures in areas with gassy soils based on an extensive literature review. We identify two potential destabilization mechanisms: gas bubbles in the pore space lead to a reduced shear strength of the soil and/or gas induces excess pore pressures that consequently reduce the effective stress in the soil. Our evaluation of the reported mechanical and hydraulic behaviour of gassy sediments indicates that the unfavourable impact of entrapped gas on a soil's shearing resistance is not sufficient to trigger large-scale slope failures. Liquefaction failure due to high gas pressures is, however, a viable scenario in coarse-grained soils. Transferring the gas influence on the soil mechanical behaviour to constitutive models is identified as the most important prerequisite for a successful future analysis of slope stability.

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