Experimental study on volumetric behaviour of Maryland clay and the role of degree of saturation

2014 ◽  
Vol 51 (12) ◽  
pp. 1449-1455 ◽  
Author(s):  
Glen J. Burton ◽  
Daichao Sheng ◽  
David Airey
Keyword(s):  
Water Content ◽  
State Parameter ◽  
Degree Of Saturation ◽  
State Variable ◽  
Optimum Water Content ◽  
Constant Suction ◽  
Compaction Energy ◽  
Oedometer Tests ◽  
Compression Line

In this paper, the volume change behaviour of Maryland clay compacted on the wet side of standard Proctor optimum water content (with lower compaction energy) is studied in reference to the saturated reconstituted state. Oedometer tests over a range of suctions and vertical stresses have been carried out, and the results have shown that the compression index reaches a peak (approximately twice that of the reconstituted material) and then gradually reduces to the reconstituted value as the stress level is increased. The results are analyzed in a framework where the degree of saturation is treated as a state parameter and controls the slope of the unsaturated normal compression line. Tests conducted under constant suction and constant water content have been used to demonstrate the effectiveness of using the degree of saturation as a state variable.

Study on Reasonable Feature of Compaction Loess with Air Porosities

2012 ◽  
Vol 238 ◽  
pp. 441-446
Author(s):  
Jing Yang ◽  
Ling Hao Wang ◽  
Fu Li Ma ◽  
Xiao Hong Bai
Keyword(s):  
Quality Control ◽  
Water Content ◽  
Dry Density ◽  
Compression Coefficient ◽  
Optimum Water Content ◽  
Compaction Energy ◽  
Internal And External Factors ◽  
And Control ◽  
Compaction Method ◽  
Optimum Water

The degree of compaction is usually used as the compaction quality and control indicator of backfill in practical project. However, as the degree of compaction is affected by various internal and external factors, its accuracy is difficult to guarantee. In this paper, compacted loess samples were prepared under different compaction energies by normal compaction method. The curves of compression coefficient and dry density, the compression coefficient and porosity of compaction loess samples under different compaction energy are analyzed while the water content is constant. The air porosities of compaction loess samples under different compaction energy and water content are calculated and summed up. The air porosity of compaction loess samples under different compaction energy is more stable than the degree of compaction when the water content is exactly equal to the optimum water content. The rationality of using air porosity as the loess compaction quality control indicator is discussed. It is proposed using air porosity as additional indicator of compaction quality control on the condition of the loess compacted dry density meeting the requirements. The air porosity less than 6.5% is suggested as the additional quality control indictor for region backfill compaction.

Variation of Initial Soil Suction with Compaction Conditions for Clayey Soils

2012 ◽  
Vol 28 (3) ◽  
pp. 431-437 ◽  
Author(s):  
S.-R. Yang ◽  
H.-D. Lin ◽  
W.-H. Huang
Keyword(s):  
Water Content ◽  
Clay Fraction ◽  
Degree Of Saturation ◽  
Soil Suction ◽  
Clayey Soils ◽  
Test Results ◽  
Wide Range ◽  
Initial Soil ◽  
Compaction Energy ◽  
The Relationship

AbstractIn this study, the initial soil suction of as-compacted clayey soils was evaluated for various compaction conditions, covering a wide range of compaction energy and molding water content. The soil specimens were prepared by impact compaction under three levels of compaction energy. The filter paper method was used to measure the initial soil suction of as-compacted specimens. Test results indicate that the relationship between the soil suction and the molding water content is bilinear under three different compaction energies. However, the effect of compaction energy on soil suction is different for the soils with different amounts of clay fraction and is elucidated by the macro soil properties. The change of soil suction due to different compaction energies can be predicted by the void ratio and the degree of saturation.

scholarly journals HYDROMECHANICAL BEHAVIOUR OF TWO UNSATURATED SILTS: LABORATORY DATA AND MODEL PREDICTIONS

2021 ◽  
Author(s):  
Agostino Walter Bruno ◽  
Domenico Gallipoli ◽  
Joao Mendes
Keyword(s):  
Water Content ◽  
Laboratory Data ◽  
Degree Of Saturation ◽  
Model Parameters ◽  
Clayey Silt ◽  
Constant Suction ◽  
Observed Behaviour ◽  
Hydromechanical Behaviour ◽  
Soil Behaviour ◽  
Hydromechanical Model

This paper presents the results from a campaign of unsaturated and saturated isotropic tests performed on two compacted silts of different coarseness, namely a clayey silt and a sandy silt, inside triaxial cells. Some tests involved an increase/decrease of mean net stress at constant suction or an increase/decrease of suction at constant mean net stress. Other tests involved an increase of mean net stress at constant water content with measurement of suction. During all tests, the void ratio and degree of saturation were measured to investigate the mechanical and retention behaviour of the soil. The experimental results were then simulated by the bounding surface hydromechanical model of Bruno and Gallipoli (2019), which was originally formulated to describe the behaviour of clays and clayey silts. Model parameters were calibrated against unsaturated tests including isotropic loading stages at constant water content with measurement of varying suction. Loading at constant water content is relatively fast and allows the simultaneous exploration of large ranges of mean net stress and suction, thus reducing the need of multiple experiments at distinct suction levels. Predicted data match well the observed behaviour of both soils, including the occurrence of progressive yielding and hysteresis, which extends the validation of this hydromechanical model to coarser soils. Specific features of the unsaturated soil behaviour, such as wetting-induced collapse, are also well reproduced.

Evaluation of the mechanical anisotropy of lacustrine smectite clays by triaxial test analysis

2022 ◽  
Author(s):  
Jubier Alonso Jiménez-Camargo ◽  
Dora Carreon-Freyre
Keyword(s):  
Water Content ◽  
Mechanical Response ◽  
Clayey Soil ◽  
Mechanical Anisotropy ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Particle Deformation ◽  
Relevant Variable ◽  
Pressure Equalization

Abstract This paper describes the role of fabric anisotropy during clayey soil deformation. A set of triaxial tests was performed on vertical and horizontal specimens of undisturbed smectite lake sediments from Jurica, Queretaro in Mexico. The results allowed to analyze the influence of bedding and discontinuities on the mechanical behavior of Jurica clays after failure. Tests with applied low strain rates allowed pore pressure equalization within specimens with different gravimetric water content and degree of saturation. Shear failure results of undrained tests showed that deformation distributes differently in both horizontal and vertical directions and that stress may be dissipated by pore collapses, fractures and particle deformation. The experimental evidence suggests that microfabric is a relevant variable in the overall mechanical response of clayey sediments that depends on the natural fabric (bedding and discontinuities), mineralogy, and water content. A detailed analysis of Young´s Moduli (E) showed the high variability of this parameter from 108 to 409 kg/cm2 (calculated at 30% of σdmax) and its dependence on the orientation of the specimen and the water content. In addition, p’-q’ graphs illustrate the relevance of considering mechanical anisotropy in clays and provide further insights to understand the role of smectites in progressive shear deformation.

scholarly journals Modelling of oedometer tests on pellet-powder bentonite mixtures to support mock-up test analysis

2020 ◽  
Vol 195 ◽  
pp. 04004
Author(s):  
Arisleidy Mesa Alcantara ◽  
Nadia Mokni ◽  
Enrique Romero ◽  
Sebastià Olivella
Keyword(s):  
Pore Size ◽  
Water Content ◽  
Mechanical Response ◽  
Degree Of Saturation ◽  
Test Analysis ◽  
Porosity Level ◽  
Consequent Reduction ◽  
High Level ◽  
Mass Basis ◽  
Oedometer Tests

Bentonite mixtures of MX-80 (80% of high-density pellets and 20% of bentonite powder on a mass basis) have been recently proposed as a candidate material for sealing deep geological disposals of high-level radioactive waste. A loading/unloading oedometer test at constant water content has been performed on this mixture, which has been modelled using the finite element Code_Bright. The constitutive model used to represent the mechanical response is the Barcelona Expansive Model (BExM), since a multi-modal pore size distribution characterises the pore network of the mixture. During compression at constant water content, an increase in the degree of saturation and a consequent reduction of suction is induced. Consequently, two competing effects occur at different pore-size scales: (a) compression due to mean net stress increase; and (b) expansion on induced suction reduction that mainly affects the micro-porosity level inside aggregates. A sensitivity analysis has been performed to explore these effects, in which the elastic compressibility parameter at the micro-porosity scale for changes in mean effective stress plays an important role.

scholarly journals Study on the Compaction Effect Factors of Lime-treated Loess Highway Embankments

2017 ◽  
Vol 3 (11) ◽  
pp. 1008 ◽  
Author(s):  
Yuyu Zhang ◽  
Wanjun Ye ◽  
Zuoren Wang
Keyword(s):  
Water Content ◽  
Dry Density ◽  
In Situ Tests ◽  
Maximum Dry Density ◽  
Lime Content ◽  
Optimum Water Content ◽  
Compaction Energy ◽  
Highway Embankments ◽  
Optimum Water

This paper presents a study to investigate the effects of water content, lime content and compaction energy on the compaction characteristics of lime-treated loess highway embankments. Laboratory compaction tests were conducted to determine the maximum dry density  and optimum water content  of loess with different lime Contents (0, 3, 5 and 8%), and to examine the effects of water content, lime content and compaction energy on the value of  and . In situ compaction tests were performed to obtain the in situ dry density  and the degree of compaction  of different lime-treated loess. Experimental embankments with different fill materials (0, 3, 5 and 8% lime treated loess) were compacted by different rollers during in situ tests. The results indicate that  increases due to the increase of water content . Once water content exceeds , dry density  decreases dramatically. The addition of lime induced the increase of  and the decrease of . A higher compaction energy results in a higher value of  and a lower value of . The value of  achieves it’s maximum value when in situ water content  was larger than the value of  (+1-2%). The degree of compaction  can hardly be achieved to 100% in the field construction of embankments. Higher water content and compaction energy is needed for optimum compaction.

Water content - void ratio swell-shrink paths of compacted expansive soils

2002 ◽  
Vol 39 (4) ◽  
pp. 938-959 ◽  
Author(s):  
S Tripathy ◽  
KS Subba Rao ◽  
D G Fredlund
Keyword(s):  
Water Content ◽  
Void Ratio ◽  
Expansive Soils ◽  
Degree Of Saturation ◽  
Test Results ◽  
Volumetric Change ◽  
Linear Portion ◽  
Ratio Change ◽  
Oedometer Tests ◽  
Vertical Deformations

This paper addresses the behaviour of compacted expansive soils under swell–shrink cycles. Laboratory cyclic swell–shrink tests were conducted on compacted specimens of two expansive soils at surcharge pressures of 6.25, 50.00, and 100.00 kPa. The void ratio and water content of the specimens at several intermediate stages during swelling until the end of swelling and during shrinkage until the end of shrinkage were determined to trace the water content versus void ratio paths with an increasing number of swell–shrink cycles. The test results showed that the swell–shrink path was reversible once the soil reached an equilibrium stage where the vertical deformations during swelling and shrinkage were the same. This usually occurred after about four swell–shrink cycles. The swelling and shrinkage path of each specimen subjected to full swelling – full shrinkage cycles showed an S-shaped curve (two curvilinear portions and a linear portion). However, the swelling and shrinkage path occurred as a part of the S-shaped curve, when the specimen was subjected to full swelling – partial shrinkage cycles. More than 80% of the total volumetric change and more than 50% of the total vertical deformation occurred in the central linear portion of the S-shaped curve. The volumetric change was essentially parallel to the saturation line within a degree of saturation range of 50–80% for the equilibrium cycle. The primary value of the swell–shrink path is to provide information regarding the void ratio change that would occur for a given change in water content for any possible swell–shrink pattern. It is suggested that these swell–shrink paths can be established with a limited number of tests in the laboratory.Key words: expansive soils, oedometer tests, swell–shrink behaviour, shrinkage tests.

A novel approach to evaluating the compaction control of soils

2020 ◽  
Vol 53 (3) ◽  
pp. 452-459 ◽  
Author(s):  
Satoru Shimobe ◽  
Giovanni Spagnoli
Keyword(s):  
Water Content ◽  
Soil Compaction ◽  
Energy Levels ◽  
Degree Of Saturation ◽  
Dry Density ◽  
Compacted Clay ◽  
Compacted Soils ◽  
Novel Approach ◽  
Compaction Curve ◽  
Compaction Energy

Soil compaction is an important operation during the construction of road embankments, railway subgrade, earth dams and compacted clay liners for waste disposal. Soil compaction is usually controlled based on the ratio of the dry density of the soil to the soil water content. However, this relationship presents problems in both the laboratory and in the field when using excess compaction energy levels in cohesive soils with a high natural water content, including differences in the compaction energy levels and a reduction in strength as a result of over-compaction. The compaction curve, which considered the compaction energy levels, is usually unknown in the field and the main factors influencing the stiffness and strength of compacted soils are the dry density and the degree of saturation. We show here compaction results for soils in terms of the dry density and degree of saturation and introduce the concept of an optimum compaction line.

Use of Stiffness for Evaluating Compactness of Cohesive Pavement Geomaterials

2003 ◽  
Vol 1849 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Phillip S. K. Ooi ◽  
Jianping Pu
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Volume Change ◽  
Degree Of Saturation ◽  
Unit Weight ◽  
Soil Stiffness ◽  
Soil Plasticity ◽  
Dry Unit Weight ◽  
Swell Potential

There has been a recent push toward adoption of in-place soil stiffness as a means of assessing compactness of pavement geomaterials. From a series of low strain GeoGauge stiffness measurements made under controlled laboratory conditions on compacted silts, the variation of stiffness with water content, dry unit weight, degree of saturation, volume change upon wetting, shear strength, and soil plasticity is discussed. In general, the GeoGauge stiffness is not directly related to dry unit weight, and it peaks dry of optimum and decreases upon wetting. Soil specimens with a large stiffness also tend to be stronger, but they also tend to swell more upon wetting, implying that the shrink–swell potential is not optimized if stiffness is. These results help advance the understanding of the role of stiffness in assessing compactness of cohesive geomaterials.

scholarly journals An experimental study of the behaviour of two rockfills accounting for the effects of degree of saturation

2020 ◽  
Vol 195 ◽  
pp. 03033
Author(s):  
Roberta Ventini ◽  
Alessandro Flora ◽  
Stefania Lirer ◽  
Claudio Mancuso ◽  
Antonio Cammarota
Keyword(s):  
Mechanical Characterization ◽  
Degree Of Saturation ◽  
Size Distributions ◽  
Factors Affecting ◽  
Grain Crushing ◽  
Grain Size Distributions ◽  
Oedometer Tests

Rockfill dams have become more and more recognized for their safety, economy and adaptability to widely varying site conditions. As a contribution to the understanding of the main factors affecting the rockfill behaviour, the paper reports and discusses experimental data on several aspects relevant to the interpretation and analysis of their in-situ response. The experimental programme involved three series of oedometric tests on specimens of two different gravels having the same grading, reconstituted at the same initial relative density. Experimental observations on rockfills compressibility are presented and discussed: attention is paid to the role of degree of saturation (Sr) through the analysis of “driest”, “fully saturated” conditions, and the transition from one to the other. Grain crushing tests on dry and saturated soil particles are also reported. Grain size distributions of the specimens, both after compaction and after the oedometer tests, are compared in the paper. The results show that the effect of Sr cannot be overlooked in the mechanical characterization of the material, especially in rockfill/stress conditions prone to crushing

Sign in / Sign up

Export Citation Format

Share Document