Effect of OCR on sampling disturbance of cohesive soils and evaluation of laboratory reconsolidation procedures

2005 ◽  
Vol 42 (2) ◽  
pp. 459-474 ◽  
Author(s):  
Marika Santagata ◽  
John T Germaine
Keyword(s):  
Effective Means ◽  
Triaxial Tests ◽  
Single Element ◽  
Cohesive Soils ◽  
Stress Strain ◽  
Overconsolidation Ratio ◽  
Strain Behavior ◽  
Preconsolidation Pressure ◽  
Strength Behavior ◽  
Undrained Strength

The paper presents the results of an experimental investigation of sampling disturbance in cohesive soils through single-element triaxial tests on resedimented Boston blue clay (RBBC). The first part of the paper discusses the effect of the overconsolidation ratio (OCR) (1–8) of the soil on postdisturbance compression and undrained shear behavior. The results demonstrate that sensitivity to disturbance decreases markedly with OCR. It is also found that for the medium-sensitivity soil tested, the estimate of the preconsolidation pressure is not significantly affected by OCR. The second part of the paper discusses laboratory reconsolidation procedures. For OCR1 RBBC, the recompression method is not effective in recovering the stress–strain behavior of the soil and, for greater disturbance, provides an increasingly unsafe estimate of the strength. For OCR4, provided the reconsolidation path reproduces the path that occurred in the field, this procedure succeeds in recovering the intact stress–strain–strength behavior of the soil. SHANSEP reconsolidation was investigated for normally consolidated RBBC only. For modest levels of disturbance, this is an effective means of evaluating both the stress–strain and the strength behavior of the soil. For greater levels of disturbance, the stress–strain behavior is not fully recovered, but the method continues to provide conservative estimates of the undrained strength.Key words: sampling disturbance, clays, overconsolidation ratio, undrained strength, recompression, SHANSEP.

scholarly journals Loading rate effect on mechanical properties of an unsaturated silty sand

2021 ◽  
Vol 337 ◽  
pp. 01018
Author(s):  
Christian Barahona ◽  
Luis Sandi ◽  
Juan Carlos Rojas ◽  
Di Emidio Gemmina ◽  
Adam Bezuijen ◽  
...  
Keyword(s):  
Specific Volume ◽  
Loading Rate ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Strain Rates ◽  
Soil Behavior ◽  
Stress Strain ◽  
Loading Rates ◽  
Strain Behavior ◽  
Strain Paths

This paper presents the results of an experimental study on the effects of testing rate on stress-strain behavior and volumetric changes of soil. A series of suction-controlled triaxial tests has been performed on reconstituted specimens of a silty sand (SM), at different stress-rates and strain-rates, respectively. The stress-strain paths were applied by using a modified version of a Bishop and Wesley device (USPv2), capable of applying independently pore-water and air pressure at both ends of the soil sample. During the isotropic compression stages loading rates of 2 and 32 kPa/h have been applied under constant suction values of 15 and 45 kPa. The drained deviator stages were conducted at the same suction levels under strain rates of 0.25 and 2.50 %/h. Results are presented in terms of applied loading rates as a function of the specimens specific volume, preconsolidation pressure, soil compressibility and deviatoric stress against strain rate. A comparison of results was made to a former study, under similar testing conditions of suction and loading rates at University of Napoli Federico II. The effect of loading rate on the soil behavior seems to have an insignificant effect on the specific volume variations, for the imposed values during the testing campaign.

Anisotropic three-dimensional behavior of a normally consolidated clay

1993 ◽  
Vol 30 (5) ◽  
pp. 848-858 ◽  
Author(s):  
M.M. Kirkgard ◽  
P.V. Lade
Keyword(s):  
Pore Pressure ◽  
San Francisco ◽  
Triaxial Compression ◽  
Three Dimensional ◽  
Failure Surface ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Principal Stresses ◽  
Stress Strain ◽  
Strain Behavior

An experimental study is presented of the influence of the intermediate principal stress on the stress–strain, pore-pressure, and strength characteristics of a normally consolidated, natural anisotropic clay, San Francisco Bay Mud, under undrained conditions. Consolidated undrained triaxial compression tests and triaxial tests with independent control of all three principal stresses on cubical specimens were performed. The stress–strain behavior and the pore-pressure characteristics as well as the effective stress failure surface can be described as being cross-anisotropic. Key words : anisotropic soils, clays, deformation, shear strength, triaxial tests.

The Strength and Stress-Strain Behavior of the Cemented Rockfill

2012 ◽  
Vol 598 ◽  
pp. 565-568 ◽  
Author(s):  
Qi Wen Zheng ◽  
Chen Wang ◽  
Jian Wei Zhang
Keyword(s):  
Friction Angle ◽  
The Other ◽  
Triaxial Tests ◽  
Elastoplastic Material ◽  
Test Results ◽  
Maximum Volume ◽  
Volume Strain ◽  
Stress Strain ◽  
Strain Behavior ◽  
Mixing Proportion

The cemented rockfill is mixed with cement, water and the siltstone rockfill with a certain mixing proportion. To study the strength and stress-strain behavior of the cemented rockfill, two groups of triaxial tests are carried out under the saturated and consolidated-drained conditions. One group specimens don’t include cement while the other group specimens include. The test results show that the cemented rockfill is a kind of elastoplastic material and the structure of the cemented rockfill is forced due to the effect of cementation. Compared with rockfill, the initial tangent elastic modulus, strength and cohesion of the cemented rockfill increase apparently, the residual strength and internal friction angle of the cemented rockfill increase a little, the maximum volume strain of the cemented rockfill decreases apparently.

Study on Stress-Strain Behavior of Cohesive Soil Mixing with Gravel by Triaxial Test

2012 ◽  
Vol 446-449 ◽  
pp. 1573-1576
Author(s):  
Yuan Long Wang ◽  
Jun Gao Zhu ◽  
Jian Fang Zhou
Keyword(s):  
Shear Strength ◽  
Young’S Modulus ◽  
Triaxial Test ◽  
Cohesive Soil ◽  
Peak Strength ◽  
Triaxial Tests ◽  
Mechanical Behaviors ◽  
Stress Strain ◽  
Strain Behavior ◽  
Soil Mixing

The mechanical behaviors of a cohesive soil mixing with gravel were investigated in consolidated-drained triaxial tests. Three soils with different percentages of gravel mixed with the cohesive soil, i.e. 50%, 75% and 87.5%, were tested, and the inference of gravel percentage to the stress-strain behavior is investigated. The results indicate that the shear strength of the soil increases with the increase of gravel percentage. Compared to peak strength of GP50, that of GP75 and GP87.5 increases by 14.4%~32.8% and 20.9%~40.5%. The initial and secant Young’s modulus of the soil increases significantly when the gravel percentage is greater than 75%.

Experimental Study of Dynamic Resilient Modulus of Cohesive Soils in Henan

2014 ◽  
Vol 971-973 ◽  
pp. 2092-2095
Author(s):  
Yu Peng Wang ◽  
Liang Zhou
Keyword(s):  
Experimental Study ◽  
Resilient Modulus ◽  
Henan Province ◽  
Additional Analysis ◽  
Cohesive Soils ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behavior ◽  
The Past ◽  
Subgrade Soil

Subgrade soil is very important materials to support highways. Resilient modulus (MR) has been used for characterizing stress-strain behavior of base or subbase subjected to repeated traffic loadings. Several methods to estimate the resilient modulus were suggested in the past years. The main objective of this study was to test the resilient modulus in the laboratory. The Subgrade soil was selected in Henan province. Resilient modulus tests were conducted with UTM. Additional analysis was performed to discuss the factors of the test results.

Plastic deformation of an embankment on clay

1983 ◽  
Vol 20 (3) ◽  
pp. 437-452 ◽  
Author(s):  
Tien H. Wu ◽  
Jenq R. Hsu ◽  
Elfatih M. Ali
Keyword(s):  
Plastic Deformation ◽  
Horizontal Stress ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Stress Strain ◽  
Preconsolidation Pressure ◽  
Lacustrine Clay ◽  
Lower Limits ◽  
Strain Model ◽  
Range Of Values

A simplified elastic, plastic, work-hardening stress–strain model was used to analyze the results of laboratory triaxial tests on kaolinite, grundite, and a lacustrine clay from Toledo. The necessary model parameters were determined from the test results.The stress–strain model was used to compute the displacements of an embankment on clay. A sensitivity analysis was performed to evaluate the influence of the various model parameters on the computer displacements. It was found that the preconsolidation pressure, which defined the yield point and the initial horizontal stress, had the largest influence. Most of the measured displacements fall within the range of values computed with the upper and lower limits of preconsolidation pressure. The effect of plane strain, variations in the elastic modulus, and compressibility are comparatively unimportant. Keywords: clay, elasticity, embankment, plasticity, settlement, stress–strain model, triaxial tests, yielding.

scholarly journals Application of a Stress-Fractional Model for Capturing the Stress-Strain Behavior of Granular Soils

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Wei Lu ◽  
Jiangong Yang ◽  
Jinan Wang
Keyword(s):  
Geotechnical Engineering ◽  
Stress Gradient ◽  
Filler Material ◽  
Triaxial Tests ◽  
Granular Soils ◽  
Initial Material ◽  
Test Results ◽  
Stress Strain ◽  
Fractional Model ◽  
Strain Behavior

Granular soils usually serve as the filler material in geotechnical engineering. This study presents the development and application of a stress-fractional model for granular soils with different initial material states. To capture the plastic loading and flow behaviors, a subloading surface with the fractional stress gradient is used. The developed model contains twelve parameters which can be determined through triaxial tests. To validate the developed model, the well-documented test results of Firoozkuh No. 161 sand and crushed basalt are simulated and discussed. It is found that the stress-fractional model can reasonably simulate the undrained and drained behaviors of granular soils consolidated with different densities and mean effective pressures.

Profiling of overconsolidation ratio in clays by field vane

1988 ◽  
Vol 25 (1) ◽  
pp. 150-157 ◽  
Author(s):  
Paul W. Mayne ◽  
James K. Mitchell
Keyword(s):  
Shear Strength ◽  
Strain Rate ◽  
Undrained Shear Strength ◽  
Correction Factors ◽  
Test Results ◽  
Overconsolidation Ratio ◽  
Empirical Correction ◽  
Preconsolidation Pressure ◽  
Undrained Strength ◽  
Undrained Shear

The field vane (FV) has traditionally been utilized to obtain profiles of undrained shear strength in soft to medium clays. After some 40 years of experience with FV results, it has been suggested that empirical correction factors be applied to the FV data to account for the effects of strain rate, anisotropy, and disturbance on measured shear strengths. As an additional use of the device, the FV may be calibrated at each site to develop profiles of overconsolidation ratio (OCR) with depth. A data base of oedometer test results and FV strengths from 96 different clays has been compiled to use as a basis for this calibration. Key words: field vane, undrained strength, clay, overconsolidation ratio, preconsolidation pressure, shear strength, vane shear.

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