Nonlinear Constitutive Model of Soil-bentonite Based on Triaxial Tests along Different Stress Paths

To investigate the constitutive behavior of soil-bentonite, which is commonly used as the backfill of cutoff walls, a series of triaxial tests were conducted along different stress paths. The tested soil-bentonite comprises 5% Wyoming bentonite and 95% silty clay excavated from a landfill site located in Jiangsu Province, China. Some mechanical properties of the soil-bentonite, including the compression characteristic, shearing characteristic, and coupled deformation of mean and deviatoric stress, were discussed based on the test data. Then, a nonlinear constitutive model was developed under the axisymmetric condition based on a modified hypoelastic model framework. All six independent parameters included in the model were calibrated according to the test data. The mechanical behaviors that the triaxial tests revealed can be fully reflected by the nonlinear model; therefore, it can reasonably describe the stress-strain behaviors of the soil-bentonite in triaxial tests of this study and another literature. Compared with the Modified Cam-Clay model, the prediction effect for the shear strain of the nonlinear model is better. According to a large-scale in-situ test employing a soil-bentonite cutoff wall, the actual stress paths of soil-bentonite are basically included in the application scope of the nonlinear model, preliminarily indicating its applicability for practical engineering projects.

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Experimental Study of Silty Clay Plane Strain Tri-axial Test under RTC Path and Modified Cam-clay Model

Civil Engineering Journal ◽

10.28991/cej-0309112 ◽

2018 ◽

Vol 4 (3) ◽

pp. 518

Author(s):

Tao Cheng ◽

Yi Zhang ◽

Keqin Yan

Keyword(s):

Plane Strain ◽

Stress Path ◽

Physical Parameters ◽

Silty Clay ◽

Model Framework ◽

Loading Test ◽

Clay Model ◽

Modified Cam Clay ◽

Institute Of Technology ◽

Cam Clay

The character of geomaterials is affected by stress path remarkably. Under different stress paths, the stress-strain characteristics of geomaterials are difference. For the unloading path in existing engineering situation, the physical parameters and constitutive model is usually determined by loading test. The path to uninstall the actual project conditions which may be a larger error. Therefore, this work proceeding from the actual project, deep excavation of the lateral unloading condition is analysed. The tests of CTC path and RTC path on silty clay in Huangshi city of china by multi-path tri-axial plane strain are carried on in the geotechnical Engineering Laboratory of Huangshi Institute of Technology. Then, the phenomenon under the two stress paths are compared with each other and describing the differences between them. The mechanical properties in the RTC stress path is analyzed mainly. Based on the Cam-Clay model framework, then derived this material yield equation based on Cam-clay model, Laiding the foundation for the numerical analysis.

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Determination of Elastic and Plastic Subgrade Soil Parameters for Asphalt Cracking and Rutting Prediction

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196154000114 ◽

1996 ◽

Vol 1540 (1) ◽

pp. 97-104 ◽

Cited By ~ 5

Author(s):

G. Behzadi ◽

W. O. Yandell

Keyword(s):

Moisture Content ◽

Constitutive Model ◽

Permanent Deformation ◽

Triaxial Tests ◽

Deformation Analysis ◽

Soil Parameters ◽

Dry Density ◽

Silty Clay ◽

Exponential Relationship ◽

Deviator Stress

A preliminary step in the prediction of rutting and cracking in a number of accelerated loading facility trials in Australia is presented. The results of laboratory repeated load triaxial tests were used to characterize the residual and resilient deformation of a silty clay subgrade material. The analysis of permanent deformation indicated that the well-known model ∈p = INS can be used to estimate the accumulated strain at any number of loading cycles. The parameter S (the slope of the line in a plot of log ∈p –log N) was found to be independent of stress and density, but very small increases were observed as moisture content increased. The parameter I (the intercept in a plot of log ∈p –log N) was found to be most sensitive to deviator stress. The test results also indicated that I increased with increasing moisture content and decreased as dry density increased. The analysis revealed that an exponential relationship existed between I and deviator stress. This relationship was used to develop a constitutive model for silty clay based on the previously mentioned well-known model. The constitutive model obtained would be able to predict the plastic strain under any number of loads at any specified stress level. Resilient deformation analysis has shown that resilient modulus initially decreased rapidly with increasing deviator stress and then increased slightly or was nearly constant. The elastic and plastic parameters will be used as input for performance predictors such as VESYS and Mechano-Lattice.

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A Constitutive Model of Sandy Gravel Soil under Large-Sized Loading/Unloading Triaxial Tests

Advances in Civil Engineering ◽

10.1155/2021/4998351 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Pengfei Zhang ◽

Han Liu ◽

Zhentu Feng ◽

Chaofeng Jia ◽

Rui Zhou

Keyword(s):

Constitutive Model ◽

Large Scale ◽

Confining Pressure ◽

Peak Strength ◽

Triaxial Tests ◽

Model Parameters ◽

Sandy Gravel ◽

Cumulative Volume ◽

Gravel Soil ◽

Confining Pressures

Based on large-scale triaxial tests of sandy gravel materials, the strength and deformation characteristics under loading/unloading conditions are analyzed. At the same time, the applicability of the hyperbolic constitutive model to sandy gravel is studied using experimental data. The results indicate that sandy gravel under low confining pressures (0.2 and 0.4 MPa) shows a weak softening trend; the higher the confining pressure, the more obvious the hardening tendency (0.6 and 0.8 MPa) and the greater the peak strength. During unloading tests, strain softening occurs, and the peak strength increases with increasing confining pressure. During loading tests, dilatancy appears when the confining pressure is low (0.2 MPa). With increasing confining pressure (0.4, 0.6, and 0.8 MPa), the dilatancy trend gradually weakens, and the cumulative volume tric strain increases, which reflects the relevance of the stress paths. Through research, it is found that the hyperbolic constitutive model has good applicability to sandy gravel soils, and the corresponding model parameters are obtained.

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A Nonlinear Constitutive Model for Disintegrated Carbonaceous Mudstone Based on Logarithmic Functions

Advances in Civil Engineering ◽

10.1155/2021/6690169 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Xiang Qiu ◽

Jinhong Li ◽

Huangbin Jiang ◽

Hongyuan Fu ◽

Shun Yang

Keyword(s):

Constitutive Model ◽

Axial Strain ◽

Confining Pressure ◽

Deviatoric Stress ◽

Triaxial Tests ◽

Lateral Strain ◽

Logarithmic Function ◽

Stress Strain ◽

Nonlinear Constitutive Model ◽

Nonlinear Stress

To study the mechanical characteristics of the disintegrated carbonaceous mudstone (DCM), consolidated drained triaxial tests were conducted on the DCM with three degrees of compaction (i.e., 90%, 93%, and 96%). Then, the nonlinear constitutive model suitable for the DCM was established based on test results using a logarithmic function. The stress-strain characteristics of the DCM were analyzed. The results revealed that the axial strain of the DCM was positively correlated with the deviatoric stress and lateral strain. The slopes of deviatoric stress-axial strain curves decreased with the increase of axial strain and so did the slopes of the axial strain-volumetric strain curves. The strength of the DCM increased with the increase of the confining pressure and the degree of compaction. In addition, the axial strain induced by dilatancy was also positively correlated with the degree of compaction and the confining pressure. Furthermore, under triaxial loading conditions, the relationship between the stress and strain of the DCM can be expressed by a logarithmic function; based on this, a nonlinear constitutive model with ten material parameters was derived. In addition, the results of numerical tests using the model showed similar stress-strain characteristics of the DCM comparing with the triaxial tests. Hence, it indicated that the nonlinear constitutive model based on the logarithmic function can reflect the nonlinear stress-strain characteristics of the DCM.

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Constitutive Modeling for Design and Control of Magnetostrictive Galfenol Devices

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.54.13 ◽

2008 ◽

Vol 54 ◽

pp. 13-18 ◽

Cited By ~ 1

Author(s):

Marcelo J. Dapino ◽

Phillip G. Evans

Keyword(s):

Constitutive Model ◽

Nonlinear Model ◽

Constitutive Modeling ◽

Second Law ◽

Strain Response ◽

Continuum Thermodynamics ◽

Eddy Current Losses ◽

Nonlinear Constitutive Model ◽

And Control ◽

Magnetostrictive Galfenol

A dynamic, nonlinear model for magnetic induction and strain response of cubic magnetostrictive materials to 3-D dynamic magnetic fields and 3-D stresses is developed. Dynamic eddy current losses and inertial stresses are modeled by coupling Maxwell’s equations to Newton’s second law through a nonlinear constitutive model. The constitutive model is derived from continuum thermodynamics.

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Determination of the confining effect of geogrid rein-forcement from large scale triaxial tests

Can Tho University Journal of Science ◽

10.22144/ctu.jen.2016.037 ◽

2016 ◽

Vol 04 ◽

pp. 6

Author(s):

Thang, H.V.

Keyword(s):

Large Scale ◽

Triaxial Tests ◽

Confining Effect

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A nonlinear strain-rate dependent constitutive model for uncured rubber materials under large deformation

Journal of Mechanics ◽

10.1093/jom/ufaa015 ◽

2020 ◽

Vol 37 ◽

pp. 118-125

Author(s):

Weihua Zhou ◽

Changqing Fang ◽

Huifeng Tan ◽

Huiyu Sun

Keyword(s):

Constitutive Model ◽

Large Deformation ◽

Mechanical Response ◽

Uniaxial Tensile ◽

Hysteresis Phenomenon ◽

Mechanical Behaviors ◽

Nonlinear Constitutive Model ◽

Rate Dependent ◽

Parallel Networks ◽

Non Gaussian

Abstract Uncured rubber possesses remarkable hyperelastic and viscoelastic properties while it undergoes large deformation; therefore, it has wide application prospects and attracts great research interests from academia and industry. In this paper, a nonlinear constitutive model with two parallel networks is developed to describe the mechanical response of uncured rubber. The constitutive model is incorporated with the Eying model to describe the hysteresis phenomenon and viscous flow criterion, and the hyperelastic properties under large deformation are captured by a non-Gaussian chain molecular network model. Based on the model, the mechanical behaviors of hyperelasticity, viscoelasticity and hysteresis under different strain rates are investigated. Furthermore, the constitutive model is employed to estimate uniaxial tensile, cyclic loading–unloading and multistep tensile relaxation mechanical behaviors of uncured rubber, and the prediction results show good agreement with the test data. The nonlinear mechanical constitutive model provides an efficient method for predicting the mechanical response of uncured rubber materials.

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Nonlinear Constitutive Model of Rock Joint in Geological Structure and Application of Implicit Return Mapping Algorithm

Arabian Journal for Science and Engineering ◽

10.1007/s13369-021-05851-w ◽

2021 ◽

Author(s):

Wenlin Feng ◽

Chunsheng Qiao ◽

Ming-Yu Feng ◽

Tan Wang ◽

Ziqi Jia

Keyword(s):

Constitutive Model ◽

Rock Joint ◽

Geological Structure ◽

Mapping Algorithm ◽

Nonlinear Constitutive Model ◽

Return Mapping ◽

Return Mapping Algorithm

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Demographic Characterization of Anonymous Trace Travel Data

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2526-03 ◽

2015 ◽

Vol 2526 (1) ◽

pp. 19-28 ◽

Cited By ~ 2

Author(s):

Joshua Auld ◽

Abolfazl (Kouros) Mohammadian ◽

Marcelo Simas Oliveira ◽

Jean Wolf ◽

William Bachman

Keyword(s):

Test Data ◽

Large Scale ◽

Travel Demand ◽

Null Model ◽

Demographic Characteristics ◽

Travel Pattern ◽

Data Set ◽

Trace Data ◽

Demographic Models ◽

Pattern Information

Research was undertaken to determine whether demographic characteristics of individual travelers could be derived from travel pattern information when no information about the individual was available. This question is relevant in the context of anonymously collected travel information, such as cell phone traces, when used for travel demand modeling. Determining the demographics of a traveler from such data could partially obviate the need for large-scale collection of travel survey data, depending on the purpose for which the data were to be used. This research complements methodologies used to identify activity stops, purposes, and mode types from raw trace data and presumes that such methods exist and are available. The paper documents the development of procedures for taking raw activity streams estimated from GPS trace data and converting these into activity travel pattern characteristics that are then combined with basic land use information and used to estimate various models of demographic characteristics. The work status, education level, age, and license possession of individuals and the presence of children in their households were all estimated successfully with substantial increases in performance versus null model expectations for both training and test data sets. The gender, household size, and number of vehicles proved more difficult to estimate, and performance was lower on the test data set; these aspects indicate overfitting in these models. Overall, the demographic models appear to have potential for characterizing anonymous data streams, which could extend the usability and applicability of such data sources to the travel demand context.

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