scholarly journals The Application of Improved Duncan-Chang Model in Unloading Soil

2014 ◽  
Vol 8 (1) ◽  
pp. 410-415 ◽  
Author(s):  
Yi He ◽  
Xuejun Chen
Keyword(s):  
Triaxial Test ◽  
Stress Path ◽  
Model Parameters ◽  
Silty Clay ◽  
True Triaxial Test ◽  
Stress Strain ◽  
Foundation Pit ◽  
Foundation Soil ◽  
Strain Relationship ◽  
Chang Model

On the basis of the representative samples of silty clay found in Wuhan, China, the lateral unloading of soil’s stress path produced by excavating foundation pit engineering, was simulated by triaxial experiment. A series of consolidated- drained true triaxial test and normal triaxial test were conducted. According to the results of tests, the parameter of the Duncan-Chang Model was determined. A modulus formula was used for the foundation soil in the lateral unloading stress path tests to replace the modulus formula of Duncan-Chang Model based on the σ3 =const . Moreover, the Duncan- Chang hyperbola nonlinear elastic constitutive model was used to simulate the plane strain test. A method to improve the ability of Duncan-Chang model in order to take into account the effects of the intermediate principal stress on the strength and deformation was presented as well as all the model parameters were also determined. The adaptability of the model for unloading the stress path was verified by comparing the theoretical stress-strain relationship and empirical stress-strain relationship.

scholarly journals Calculation of Tangent Modulus of Soils under Different Stress Paths

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Hua Huang ◽  
Min Huang ◽  
Jiangshu Ding
Keyword(s):  
Triaxial Compression ◽  
Confining Pressure ◽  
Tangent Modulus ◽  
Engineering Practice ◽  
Silty Clay ◽  
Stress Strain ◽  
Foundation Pit ◽  
Calculation Results ◽  
Chang Model ◽  
Initial Tangent Modulus

During excavation of foundation pit, soils of different sites may undergo different unloading paths. This study focuses on the tangent modulus of soil under different stress paths and provides theoretical basis for the deformation calculation of soil. In this paper, conventional triaxial compression test and K0 consolidation unloading test were conducted with mucky soil and silty clay to obtain the deformation characteristics of soils under different stress paths. Experiment results show that the soil samples exhibit distinct stress-strain characteristics under different stress paths, but they all show nonlinearity. The initial tangent modulus increases as the consolidation confining pressure intensifies. Then, based on the test data, the power function relationship between initial tangent modulus and confining pressure under unloading was verified. Simultaneously, a hyperbola function to express stress-strain relation of soils under the K0 consolidation unloading condition was proposed and proved. Finally, the formulas of the tangent modulus under K0 consolidation unloading were established referring to the derivation of that in Duncan–Chang model. The theoretical calculation results agree well with the test results. It can expand the use of the Duncan–Chang model and improve its application to engineering practice.

Analysis of the Deformation Characteristics of Loess Based on Thermal–Mechanical Coupling under an Energy Internet

2021 ◽  
Author(s):  
Zengle Li ◽  
Bin Zhi ◽  
Enlong Liu
Keyword(s):  
Mechanical Properties ◽  
Temperature Change ◽  
Clean Energy ◽  
Model Parameters ◽  
Stress Strain ◽  
Energy Internet ◽  
Influence Of Temperature ◽  
Medium Model ◽  
Strain Relationship ◽  
Natural Loess

In response to the major challenges faced by China’s transition to green low-carbon energy under the dual-carbon goal, the use of energy Internet cross-boundary thinking will help to develop research on the integration of renewable clean energy and buildings. Energy piles are a new building-energy-saving technology that uses geothermal energy in the shallow soil of the Earth’s surface as a source of cold (heat) to achieve heating in winter and cooling in summer. It is a complex thermomechanical working process that changes the temperature of the rock and soil around the pile, and the temperature change significantly influences the mechanical properties of natural loess. Although the soil temperature can be easily and quickly obtained by using sensors connected to the Internet of Things, the mechanical properties of natural loess will change greatly under the influence of temperature. To explore the influence of temperature on the stress–strain relationship of structural loess, the undrained triaxial consolidation tests were carried out under different temperatures (5, 20, 50 and 70∘C) and different confining pressures (50, 100, 200 and 400[Formula: see text]kPa), and a binary-medium model was introduced to simulate the stress–strain relationship. By introducing the damage rate under temperature change conditions, a binary-medium model of structural loess under variable temperature conditions was established, and the calculation method of the model parameters was proposed. Finally, the calculated results were compared with the test results. The calculation results showed that the established model has good applicability.

Sand deformation under proportional loading

1986 ◽  
Vol 23 (2) ◽  
pp. 155-163 ◽  
Author(s):  
D. Negussey ◽  
Y. P. Vaid
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Stress Ratio ◽  
Proportional Loading ◽  
Stress Strain ◽  
Independent State ◽  
State Variable ◽  
Strain Components ◽  
Strain Relationship ◽  
Observed Behaviour

A fundamental experimental study of sand behaviour under low stress ratio proportional loading wherein all strain components are contractant is presented. Experimentally observed behaviour under stress conditions of the triaxial test led to a coherent framework for representing proportional loading stress–strain response. The stress–strain relationship formulated incorporates relative density as an inherent independent state variable and does not require appeal to material isotropy. Key words: triaxial test, proportional loading, sand, relative density, energy density, stress increment, strain increment.

scholarly journals Down-Hole Triaxial Test to Measure Average Stress-Strain Relationship of Rock Mass

2003 ◽  
Vol 43 (5) ◽  
pp. 53-62 ◽  
Author(s):  
Kazuo Tani ◽  
Takashi Nozaki ◽  
Susumu Kaneko ◽  
Yoshinori Toyo-Oka ◽  
Hideo Tachikawa
Keyword(s):  
Rock Mass ◽  
Triaxial Test ◽  
Average Stress ◽  
Stress Strain ◽  
Strain Relationship ◽  
Relationship Of

Dynamic Stress-Strain Relationship of Saturated Clay by Dynamic Triaxial Test

2011 ◽  
Vol 250-253 ◽  
pp. 3183-3186
Author(s):  
Jian Yi Yuan
Keyword(s):  
Triaxial Test ◽  
Dynamic Stress ◽  
Soft Clay ◽  
Confining Pressure ◽  
Dynamic Shear ◽  
Stress Strain ◽  
Dynamic Triaxial Test ◽  
Wide Range ◽  
Strain Relationship ◽  
Relationship Of

Subgrade diseases are exposed more and more serious with raising speed of existing railway in wide range. Fro the complexity of dynamic stress-strain relationship of soil, dynamic triaxial test was used to analyze .the dynamic mechanics behavior under cyclic train load for saturated soft clay in Yangtze Delta region. Compaction coefficient, confining pressure, dynamic shear strsss ratio, inputing stimulus and loading frequence were taken into account in test. The results show that the dynamic stress-strain curves of soil specimen are provided with prominent hysteretic characteristics and area surrounded by hysteretic curves gradually augment and slope of hysteretic curve decreases with the increase of dynamic shear train amplitude. The strong correlation exists between dynamical stress and strain.

The Studies of Rock Damage Softening Statistical Constitutive Model under True Triaxial Stress State

2014 ◽  
Vol 580-583 ◽  
pp. 312-315
Author(s):  
Hui Mei Zhang ◽  
Xiang Miao Xie ◽  
Geng She Yang
Keyword(s):  
Constitutive Model ◽  
Strain Curve ◽  
Stress Path ◽  
Complex Stress ◽  
Model Parameters ◽  
Stress Strain ◽  
Deformation And Failure ◽  
True Triaxial ◽  
Complex Stress Path ◽  
The Impact

From the feature of rock micro-unit failure obeys Poisson random distribution, the damage softening statistical constitutive of was established under true triaxial confinement based on D-P criterion, so the impact of the intermediate principal stress on rock deformation and failure was considered in theory, and the actual engineering rock complex stress path evolution was reflected more realistically. Furthermore, according to the geometrical conditions of stress-strain relationship, the theoretical relationship between constitutive model parameters and the stress-strain curve characteristic parameters during the process of rock softening and deforming, which enhance the adaptability of the model. Finally, the rationality of the model verified by the measured data.

Analysis of the Mechanic Behavior and Rutting of Asphalt Concrete Using a Sand Model

1999 ◽  
Vol 15 (4) ◽  
pp. 177-184
Author(s):  
Ming-Lou Liu
Keyword(s):  
Asphalt Concrete ◽  
Stress Path ◽  
Plasticity Model ◽  
Test Results ◽  
Research Subjects ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Relationship ◽  
Concrete Materials ◽  
Relationship Of

AbstractThe stress-strain relationship of the sand and asphalt concrete materials is one of the most important research subjects in the past, and many conctitutive laws for these materials have been proposed in the last two decades. In this study, the Vermeer plasticity model is modified and used to predict the behavior of the sand and asphalt concrete materials under different stress path conditions. The results show that the predictions and test results agree well under different stress path conditions. However, the orignal Vermeer model can not predict the stress-strain behavior of the asphalt concrete. Finally, the modified Vermeer plasticity model is incorporated with the pavement rutting model to predict the rut depth of pavement structure under traffic loadings.

Laboratory Triaxial Test Study on Soil Reinforced with Roots of Manilagrass

2011 ◽  
Vol 250-253 ◽  
pp. 1366-1370 ◽  
Author(s):  
Kai Fu Liu ◽  
Xiang Ru Yang ◽  
Xin Yu Xie ◽  
Chang Fu Wu ◽  
Yong Hai Liu
Keyword(s):  
Shear Strength ◽  
Triaxial Test ◽  
Triaxial Tests ◽  
Stress Strain ◽  
Research Results ◽  
Test Study ◽  
Strain Relationship ◽  
Optimal Quantity ◽  
Better Than

Laboratory triaxial tests of the soil reinforced with roots of Manilagrass were carried out in order to understand the stress-strain relationship. The change of shear strength indexes of the soil reinforced with roots of Manilagrass was investigated with the quantity of grassroots planted in the soil specimens. The results of laboratory triaxial tests show that the strength and capacity for resisting the deformation of soil reinforced with roots are better than those of unreinforced soil. And under the certain number of grassroots layers, the strength and capacity for resisting the deformation of soil reinforced with roots increase firstly and then reduce with the increasing of Manilagrass roots quantity. In other words, there is an optimal quantity of Manilagrass roots affecting the strength and capacity for resisting the deformation of soil reinforced with roots. The research results are important for understanding the mechanism and use of vegetation protection for slope.

Large-Scale True Triaxial Test on Stress-Strain and Strength Properties of Rockfill

2020 ◽  
Vol 20 (1) ◽  
pp. 04019146 ◽  
Author(s):  
Jiajun Pan ◽  
Jiwei Jiang ◽  
Zhanlin Cheng ◽  
Han Xu ◽  
Yongzhen Zuo
Keyword(s):  
Triaxial Test ◽  
Large Scale ◽  
Strength Properties ◽  
True Triaxial Test ◽  
Stress Strain ◽  
True Triaxial

A deep retaining structure in till and sand. Part I: Stress path effects

1983 ◽  
Vol 20 (1) ◽  
pp. 120-130 ◽  
Author(s):  
L. V. Medeiros ◽  
Z. Eisenstein
Keyword(s):  
Plane Strain ◽  
Principal Stress ◽  
Stress Path ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Stress Strain ◽  
Retaining Structure ◽  
Major Principal Stress ◽  
Minor Principal Stress ◽  
Passive Compression

Laboratory investigation of the stress–strain behaviour of glacial till (stiff silty clay) and dense preglacial sand have been carried out. Special attention has been devoted to investigation of the influence of different stress paths on the stress–strain response of these materials. Since these tests were performed primarily for an analytical study of the behaviour of a deep retaining structure, the stress paths chosen for testing were typical of stress conditions for this field situation. Triaxial and plane strain drained tests on till were run in passive compression (with increasing major principal stress and constant minor principal stress) and in active compression (with constant major principal stress and decreasing minor principal stress). On the sand, only triaxial tests were carried out. These experiments were in passive compression and in active extension (with decreasing major principal stress and constant minor principal stress).The results of different tests were compared at corresponding stress and strain levels. They indicated an appreciably decreased stiffness along the passive compression stress path compared with that in the active compression and active extension tests. Also, a comparison between the triaxial and plane strain tests for the till showed a marked influence of the intermediate principal stress. Although the results were intended for use in a stress path dependent, nonlinear elastic analysis they are discussed and explained in terms of a more general elastoplastic model of soil behaviour. Keywords: stress–strain relationship, stress path, laboratory testing, stiff clay, dense sand.

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