Undrained Creep Behavior of a Silty Clay in Triaxial Tests

2011 ◽  
Author(s):  
Jun-Gao Zhu ◽  
Yan-Hui Zhao ◽  
Jian-Hua Yin
Keyword(s):  
Creep Behavior ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Undrained Creep

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

Comparative study of coral sand and silica sand in creep under general stress states

2017 ◽  
Vol 54 (11) ◽  
pp. 1601-1611 ◽  
Author(s):  
Yaru Lv ◽  
Feng Li ◽  
Yawen Liu ◽  
Pengxian Fan ◽  
Mingyang Wang
Keyword(s):  
Grain Size ◽  
Creep Behavior ◽  
Confining Pressure ◽  
Silica Sand ◽  
Triaxial Tests ◽  
Particle Crushing ◽  
Particle Rotation ◽  
General Stress ◽  
Coral Sand ◽  
Stress States

Coral sand has individual characteristics that differ from silica sand, such as creep behavior that is always attributed to particle crushing under high stress states. To understand the creep behavior of coral sand under general stress levels, three series of comparative triaxial tests relevant to the deviator stress, confining pressure, and relative density were performed on coral sand and silica sand creeping for more than 5 days. The volumetric, axial, and shear creeps of coral sand are considerably larger than those of silica sand, particularly under a relatively high confining pressure. The volumetric creep strain of coral sand was found to be contractive, but that of silica sand appeared dilative according to the creep time. This difference is not mainly governed by particle crushing in coral sand because the grain-size distribution prior to and after creep is similar. The grain skeletons were observed using a scanning electron microscope, finding that, independent of the grain size and shape, the coral grains include large amounts of cavities. The creep of coral sand under general stress conditions is mainly caused by particle interlocking, i.e., the angular regions of some particles interlock into the cavities of other particles due to particle rotation. This structuration is induced by breakage of asperities and voids during creep such as the local instability near cavities.

SOME OBSERVATIONS ON THE UNDRAINED SHEARING STRENGTH USED TO ANALYZE A FAILURE

1969 ◽  
Vol 6 (2) ◽  
pp. 97-110 ◽  
Author(s):  
F. A. De Lory ◽  
R. J. Salvas
Keyword(s):  
Clay Soils ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Compression Tests ◽  
Foundation Soil ◽  
Shearing Strength

The undrained shearing strength of the foundation soil at the site of a failure of a low embankment was investigated by several methods. It was found that both field vane and laboratory compression tests tended to underestimate the strength required for stability. Further consideration of the test specimens from sample tubes showed the undrained shearing strength varied considerably with the position of the sample in the tube. Specimens from tubes from another site yield the same type of results. The two silty clay soils involved were studied in more detail using CIU and CAU triaxial tests and comparing cu/p′ ratios. It was found that in general they yielded the values usually obtained for lacustrine clays.

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

1996 ◽  
Vol 1540 (1) ◽  
pp. 97-104 ◽  
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.

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.

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

2020 ◽  
Author(s):  
Pengcheng Ma ◽  
Han Ke ◽  
Xing Tong ◽  
Yun Min Chen
Keyword(s):  
Constitutive Model ◽  
Test Data ◽  
Nonlinear Model ◽  
Large Scale ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Cutoff Wall ◽  
Model Framework ◽  
Nonlinear Constitutive Model ◽  
Modified Cam Clay

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.

scholarly journals Critical Dynamic Stress and Accumulative Deformation Evolution of Embankment Silty Clay Subjected to Cyclic Freeze-Thaw

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Lina Wang ◽  
Zhiyu Weng ◽  
Tianliang Wang ◽  
Qiang Liu ◽  
Guoyu Li ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Dynamic Stress ◽  
Permanent Deformation ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Critical Dynamic ◽  
Permanent Settlement ◽  
Embankment Stability

In cold regions, the permanent settlement of embankment is mainly caused by the repeated freeze-thaw process and long-term repeated train loads. Meanwhile, the critical dynamic stress (σdcr) is an important parameter index for determining embankment stability. Therefore, the accumulative permanent deformation evolution and critical dynamic stress of embankment soil subjected to cyclic freeze-thaw were studied using dynamic triaxial tests. Firstly, a numerical model for calculating critical dynamic stress considering the repeated freeze-thaw process was proposed, which shows that the critical dynamic stress of embankment soil rapidly decreases in the first two repeated freeze-thaw cycles, whereas it tends to be stable after the subsequent freeze-thaw process. Next, based on the normalization of the critical dynamic stress, an explicit model for predicting accumulative plastic strain (εp) of embankment soil was established. The above model considers freeze-thaw times, repeated dynamic stress amplitude (σd), and loading times, in which all material parameters of Qinghai-Tibet silty clay were presented. Thus, the critical dynamic stress and accumulative plastic strain models established in this paper can be applied to judge the embankment stability and predict the embankment settlement induced by train loads in cold regions.

scholarly journals Prediction of unsaturated shear strength from microstructurally based effective stress

2019 ◽  
Vol 92 ◽  
pp. 07005
Author(s):  
Régis Mpawenayo ◽  
Pierre Gerard
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Mercury Intrusion Porosimetry ◽  
Clay Soil ◽  
Large Range ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Wide Range ◽  
Silty Clay Soil

This work aims at investigating the adequacy of microstructurally based effective stress to predict the shear strength of unsaturated soils over a wide range of suction. For that purpose, shear strength data are acquired on a silty clay soil through two types of unsaturated triaxial tests: suction controlled triaxial tests and unconsolidated triaxial tests at constant water content. The microstructure of the soil is determined with Mercury Intrusion Porosimetry and is directly used in different expressions of microstructurally based effective stresses available in the literature. The large range of suction tested allows to determine the most consistent expression of the effective stress to reproduce the experimental observations.

scholarly journals Experimental Testing and Numerical Modelling of Mechanical Behaviors of Silty Clay under Freezing-Thawing Cycles

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Tianfei Hu ◽  
Dawei Liu ◽  
Hui Wu
Keyword(s):  
Numerical Modelling ◽  
Experimental Testing ◽  
Axial Strain ◽  
Volumetric Strain ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Silty Clay ◽  
Test Results ◽  
Mechanical Behaviors ◽  
Physical Weathering

Seasonal freezing-thawing cycle is one of the most common physical weathering processes in cold regions, which can significantly affect the mechanical behaviors of soil. In this paper, a series of freezing-thawing (F-T) cycle and consolidated drained triaxial tests have been carried out on silty clay samples collected from Tibetan Plateau. To do so, a modified numerical model was developed taking into F-T effect. Test results showed that the stress-strain curves of original soil specimens presented strain hardening characteristics, accompanied with shear shrinkage. In F-T experienced specimens, volumetric strain in triaxial loading stage was gradually increased, while failure strength was decreased. Elliptic and parabolic functions were selected in numerical modelling to describe volume and shear yield surfaces on a p-q plane, respectively. Moreover, a double-yield surface constitutive model was developed to describe relationships among deviatoric stress, axial strain, and volumetric strain. Furthermore, equations for model parameters with the number of F-T cycles as variable were derived based on the triaxial test results which were then substituted into the established model to take into account the effects of F-T cycles. Finally, numerical results were validated with experimental findings.

Behavior of Mexico City clay subjected to undrained repeated loading

1989 ◽  
Vol 26 (1) ◽  
pp. 159-162 ◽  
Author(s):  
J. Abraham Diaz-Rodriguez
Keyword(s):  
Water Content ◽  
Mexico City ◽  
High Water ◽  
Elastic Behavior ◽  
Triaxial Tests ◽  
High Water Content ◽  
Repeated Loading ◽  
Silty Clay ◽  
Undisturbed Soil ◽  
Very High

This note describes a series of cyclic triaxial tests on undisturbed soil samples of Mexico City clay, obtained near the SCT building. The site is a silty clay deposit of a very high water content and soft consistency. The material exhibits elastic behavior in spite of its very high water content. Three empirical relationships describing an equivalent Young's modulus, an equivalent damping ratio, and a cyclic stress level, associated with cyclic strain level, were obtained. Test results define two different patterns of strength loss. Key words: undrained strength, repeated load, clay, modulus, damping, Mexico City.

Sign in / Sign up

Export Citation Format

Share Document