scholarly journals Experimental and analytical investigations of volume change behaviour of saturated expansive soils in oedometer test

2019 ◽  
Vol 92 ◽  
pp. 10006
Author(s):  
Misa Hiraga ◽  
Hiroyuki Kyokawa ◽  
Junichi Koseki
Keyword(s):  
Expansive Soils ◽  
Swelling Behaviour ◽  
Oedometer Test ◽  
Lower Shear ◽  
Lateral Contraction ◽  
Mechanical Behaviours ◽  
Water Saturated ◽  
Electrochemical Phenomena ◽  
Mechanical Consolidation ◽  
Oedometer Tests

The chemical and mechanical behaviours of saturated bentonite were experimentally and analytically investigated. A series of oedometer tests on saturated bentonite was conducted. By replacing the cell fluid during the oedometer test, one-dimensional osmotic consolidation and swelling behaviour were observed. The experimental results were simulated numerically using a constitutive model by considering the influence of electrochemical phenomena of clay mineral crystals on the macrostructural behaviour. It was concluded that the typical mechanical swellability of water-saturated bentonite in oedometer test is affected by a positive dilatancy behaviour due to the lower shear strength. After the osmotic consolidation test, a lateral contraction of the specimen in the oedometer was observed; this affected the compressibility during the subsequent mechanical consolidation. It was also concluded that the concentration of Na+ in the pore fluid affects the specific mechanical properties of bentonite.

scholarly journals Combined effect of mineralogical and chemical parameters on swelling behaviour of expansive soils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bendadi Hanumantha Rao ◽  
Peddireddy Sreekanth Reddy ◽  
Bijayananda Mohanty ◽  
Krishna R. Reddy
Keyword(s):  
Expansive Soils ◽  
Research Work ◽  
Swelling Pressure ◽  
Combined Effect ◽  
Practical Significance ◽  
Chemical Compositions ◽  
Chemical Parameters ◽  
Swelling Behaviour ◽  
Mineral Contents ◽  
Swelling Properties

AbstractMicrolevel properties such as mineralogical and chemical compositions greatly control the macro behaviour of expansive soils. In this paper, the combined effect of mineral (i.e. montmorillonite, MMC) and chemical contents (i.e. Ca and Na in their total (T), leachable (L) and exchangeable form (CEC)) on swelling behaviour is investigated in a comprehensive way. Several 3-dimensional (3D) graphs correlating MMC and Ca/Na ratio, together, with swelling property (swelling potential, Sa, and swelling pressure, Sp) are developed. 3D plots, in general, portrayed a non-linear relationship of Sa and Sp with MMC and Ca/Na ratio, together. It is hypothesized that swelling initially is triggered by chemical parameters due to their quick and rapid ionization capability, but the overall swelling phenomenon is largely controlled by MMC. It is importantly found that expansive soils are dominant with divalent Ca++ ions up to MMC of 67% and beyond this percentage, monovalent Na+ ions are prevalent. From the interpretation of results, the maximum Sa of 18% and Sp of 93 kPa is measured at MMC of 43%, (Ca/Na)T of 10–14 and (Ca/Na)L of 2–7. It is concluded from study that total CEC + MMC for determining Sa and (Ca/Na)T + MMC for determining Sp are superior parameters to be considered. The findings of the study also excellently endorsed the results of Foster32, who stated that ionization of Na or Ca depends on the constituent mineral contents. The findings presented herein are unique, interesting and bear very practical significance, as no earlier research work reported such findings by accounting for chemical and mineralogical parameters impact, in tandem, on swelling properties.

In situ estimation of the coefficient of consolidation in clays

1990 ◽  
Vol 27 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Mohammed G. Kabir ◽  
Alan J. Lutenegger
Keyword(s):  
Key Words ◽  
Pore Pressure ◽  
Reference Values ◽  
Time Factors ◽  
In Situ Tests ◽  
Coefficient Of Consolidation ◽  
Oedometer Test ◽  
Undisturbed Samples ◽  
Oedometer Tests

An investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays. Coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests. Three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests. Results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions, to provide reference values of cv and ch. The results of investigations conducted at several clay sites are presented. Key words: in situ tests, piezocone, piezoblade, coefficient of consolidation, oedometer test, clays.

scholarly journals The Use of Geogrids in Mitigating Pavement Defects on Roads Built over Expansive Soils

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Richard Shumbusho ◽  
Gurmel S. Ghataora ◽  
Michael P.N. Burrow ◽  
Digne R. Rwabuhungu
Keyword(s):  
Seasonal Changes ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Real Field ◽  
Experimental Program ◽  
Swelling Potential ◽  
Swelling Behaviour ◽  
Wetting And Drying ◽  
Potential Benefits

This study was conducted to investigate the potential benefits of using geogrids in mitigating pavement defects notably roughness and longitudinal cracking on pavements built over expansive soils. The seasonal changes of expansive soils (periodic wetting and drying) cause detrimental effects on the overlying road pavements. Such detrimental behavior of expansive soils was simulated in a controlled laboratory environment through allowing cyclic wetting and drying of an expansive soil underlying a pavement section. The shrink/swell effects of the expansive soil subgrade were examined through monitoring its change in moisture, and measuring deformation of overlying pavement section. The experimental study suggested that a geogrid layer in a reinforced pavement section can reduce surface differential shrinking and swelling deformation resulting from underlying expansive soils by a factor of 2 and 3 respectively in comparison to unreinforced section. Given that an oedometer test which is typically used to predict swelling potential of expansive soils is known to overpredict in-situ soil swell, experimental program also investigated quantitatively the extent to which the oedometer can overestimate swelling behaviour of the real-field scenarios. It was found that oedometer percent swell can overpredict in-situ swelling behaviour of the expansive soil by a factor ranging between 2 and 10 depending upon the period over which the in-situ expansive soil has been in contact with water.

Swell-Shrinkage Behavior of Remolded Expansive Soils

2011 ◽  
Vol 243-249 ◽  
pp. 3050-3055
Author(s):  
Cheng Yu ◽  
Jin Cheng Wei
Keyword(s):  
Laboratory Tests ◽  
Expansive Soils ◽  
Initial State ◽  
Swelling Behaviour ◽  
Moisture Contents ◽  
State Index ◽  
Logarithmic Relationship ◽  
Initial Results ◽  
Unique Relationship ◽  
Shrinkage Behavior

The swelling behaviour of compacted expansive soils have been studied with variation in initial state. For comparison, a series of swell and shrinkage capacity laboratory tests with different initial dry densities，moisture contents and pressures have also been made with three different consistency state. Both percent swell and shrinkage are significantly influenced by the consistency state index. There is an unique relationship between percent swell and consistency state index of the soil. The percent swell-load relationship could be identified as a logarithmic relationship facilitating the prediction of ultimate percent swell under different load with a few initial results.

scholarly journals Determination of Creep Properties of Clays from VRS Oedometer Tests

2019 ◽  
Vol 38 (2) ◽  
pp. 1857-1871 ◽  
Author(s):  
Tim Tapani Länsivaara
Keyword(s):  
Soft Clay ◽  
Complex Stress ◽  
Soil Parameters ◽  
Rate Variation ◽  
Additional Parameter ◽  
Creep Properties ◽  
Oedometer Test ◽  
Wide Range ◽  
Oedometer Tests

AbstractThe determination of creep properties still relies almost entirely on the incrementally loaded oedometer test introduced about 100 years ago. Although the simplicity of the test assures a robust evaluation of soil parameters, it also introduces some shortcomings like discontinuity of the evaluated parameters and the long duration of the test. In this study, the performance of the variable rate of strain (VRS) oedometer test for determination of creep properties of a sensitive soft clay is studied. The results from a comprehensive test series of VRS oedometer tests on a soft sensitive clay is presented. Three different setups for the strain rate variation were used, and each test was repeated thrice. The tests showed good consistency and yielded equal creep parameters compared to values from traditional incrementally loaded (IL) oedometer tests. The tests further verified that it is possible to describe the complex stress dependency of creep parameters with just one additional parameter to the primary deformation parameters. Compared to the IL tests, the VRS tests offers a faster determination and continuous creep properties for a wide range of stress.

An oedometer test study on the preconsolidation stress of glaciomarine clays

2003 ◽  
Vol 40 (5) ◽  
pp. 857-872 ◽  
Author(s):  
J L.H Grozic ◽  
T Lunne ◽  
S Pande
Keyword(s):  
Stress History ◽  
Traditional Methods ◽  
Testing Procedures ◽  
Oedometer Test ◽  
Test Study ◽  
Using Data ◽  
Plastic Clays ◽  
Disturbed Soils ◽  
Oedometer Tests ◽  
Test Stress

Stress history is usually determined by interpreting the results of oedometer tests to obtain the preconsolidation stress using traditional methods such as those proposed by Casagrande and Janbu. Both these methods are based on the assumption that the soil experiences a change in stiffness, from a stiff response to a soft response, close to the preconsolidation stress. Disturbed soils, however, especially overconsolidated clays of low plasticity, exhibit a soft response at low stresses, thereby making the interpretation of oedometer tests using traditional methods extremely difficult. Using data mainly from the Haltenbanken area, offshore Norway, a study was undertaken to investigate the various methods and testing procedures available to determining stress history. Oedometer verification tests were also performed on reconstituted specimens to compare interpreted values with the actual applied preconsolidation stress. This paper describes the results of the study by illustrating the variation in the interpretation methods and testing procedures used to determine preconsolidation stress.Key words: preconsolidation stress, yield stress, overconsolidated, low plastic clays, oedometer test, stress history.

Influence of Randomly Distributed Waste Tire Fibres on Swelling Behaviour of Expansive Soils

2020 ◽  
pp. 319-332
Author(s):  
Tejaswani Shukla ◽  
Mohit Mistry ◽  
Chandresh Solanki ◽  
Sanjay Kumar Shukla ◽  
Shruti Shukla
Keyword(s):  
Expansive Soils ◽  
Swelling Behaviour ◽  
Waste Tire

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.

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