Internal erosion of gravelly mudstone due to drying/wetting and hydraulic pressure cycles in oedometer test.

2021 ◽  
Author(s):  
Noor M. Mohamed Nihaaj ◽  
Takashi Kiyota ◽  
Matthew Gapuz Chua
Keyword(s):  
Particle Breakage ◽  
Internal Erosion ◽  
Hydraulic Pressure ◽  
Combined Effects ◽  
Loading Conditions ◽  
Vertical Load ◽  
Vertical Strain ◽  
Oedometer Test ◽  
Penetration Tests ◽  
Oedometer Tests

When disintegrated mudstone due to the slaking, subjected to hydraulic pressure, could lead to internal erosion. To examine the combined effects of slaking and internal erosion of gravelly mudstone in 1D deformation under a constant vertical load, a series of modified oedometer tests and laboratory penetration tests were conducted with drying/wetting and hydraulic pressure cycles. Some loading conditions showed the sever erosion in progressing of the cycle, susceptibility of the internal erosion was evaluated in terms of non-filter and fitter factors coefficient Keywords: Vertical strain, Slaking, Internal-erosion, Particle-breakage.

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.

Numerical approach to particle breakage under different loading conditions

2004 ◽  
Vol 143-144 ◽  
pp. 130-143 ◽  
Author(s):  
C.A Tang ◽  
H.Y Liu ◽  
W.C Zhu ◽  
T.H Yang ◽  
W.H Li ◽  
...  
Keyword(s):  
Numerical Approach ◽  
Particle Breakage ◽  
Loading Conditions

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.

Evaluating the Potential for Damaging Hydraulic Pressure in the Concrete Tie Rail Seat

2010 ◽  
Author(s):  
John C. Zeman ◽  
J. Riley Edwards ◽  
David A. Lange ◽  
Christopher P. L. Barkan
Keyword(s):  
Surface Water ◽  
Effective Stress ◽  
Water Pressure ◽  
Hydraulic Pressure ◽  
Vertical Load ◽  
Critical Problem ◽  
Surface Geometry ◽  
State Of Stress ◽  
Pore Water Pressures ◽  
Prestressed Beam

Rail seat deterioration (RSD) is the most critical problem with concrete tie performance on North American freight railroads. Currently, the problem is not sufficiently understood to allow for effective solutions. RSD is considered to have up to five potential mechanisms, and this paper investigates one of them: hydraulic pressure cracking. A model of the effective stress in a concrete tie rail seat — considering the contributions of a uniform vertical load, a uniform lateral load, a prestressed beam on an elastic foundation, and pore pressure to the state of stress — was created to determine what surface water pressures at the rail seat could lead to damaging pore water pressures in the concrete. A laboratory test setup and procedure were devised to measure the surface water pressure in a laboratory rail seat using tie pads of differing material composition and geometry. Results show that the magnitude of the pressure generated and the rate of pressure dissipation with many load cycles depends on the pad material and surface geometry. Comparing the effective stress model and the measured surface pressures, hydraulic pressure cracking appears to be a feasible mechanism for RSD given the correct combination of dynamic rail seat loads, sufficient moisture, and a tie pad surface that develops high pressure.

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.

Analysis of a sanitary-embankment failure over the Rio de Janeiro soft clay deposit

1991 ◽  
Vol 28 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Renato Pinto Da Cunha ◽  
Willy Alvarenga Lacerda
Keyword(s):  
Rio De Janeiro ◽  
Soft Clay ◽  
Triaxial Tests ◽  
Guanabara Bay ◽  
Total Stress ◽  
Clay Deposit ◽  
Geotechnical Characteristics ◽  
Penetration Tests ◽  
Oedometer Tests

This paper presents the analysis of an embankment failure over a soft clay deposit in the district of Caju, Rio de Janeiro. The uncommon feature of the analysis is related to the embankment's material, which is mainly composed of dumped sanitary and rubble fill, and the unconsolidated state of the subjacent clay layer. Index tests were performed to obtain geotechnical characteristics and a profile of the soft clay deposit, which were compared with a well-known Brazilian clay from the same area (Guanabara Bay). Oedometer tests, in situ and laboratory vane tests, standard penetration tests, and conventional triaxial tests were also carried out. Total stress calculations were used to interpret and back analyze the failure and also to obtain the mobilized shear strength at both the fill and clay foundation. It was concluded that for an embankment cohesion of 0–20 kPa, the ratio between the back-analyzed Cu and the in situ postfailure Cu has a magnitude similar to the soft clay sensitivity. Key words: case history, sanitary fill, soft clay.

Effects of Retinoic Acid and 1,25-Dihydroxyvitamin D3 on IFN-gamma Secretion by Mononuclear Leukocytes from Nulliparous and Postparturient Dairy Cattle

2000 ◽  
Vol 70 (3) ◽  
pp. 92-101 ◽  
Author(s):  
Burim Ametaj ◽  
Brian Nonnecke ◽  
Ronald Horst ◽  
Donald Beitz
Keyword(s):  
Retinoic Acid ◽  
Dairy Cattle ◽  
Dairy Cows ◽  
Dairy Cow ◽  
Pokeweed Mitogen ◽  
Mononuclear Leukocytes ◽  
Combined Effects ◽  
Ifn Gamma ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D

Individual and combined effects of several isomers of retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on interferon-gamma (IFN-gamma) secretion by blood mononuclear leukocytes (MNL) from nulliparous and postparturient Holstein cattle were evaluated in vitro. In the first experiment, effects on incubation period (24 to 72 hours) and time of supplementation (0 to 32 hours) with all-trans, 9-cis, 13-cis-, and 9,13-dicis-RAs (0 to 100 nM) on IFN-gamma secretion by pokeweed mitogen (PWM)-stimulated (0 and 10 mug/ml) MNL from nulliparous cattle were evaluated. In the second experiment, MNL from postparturient cows (bled at 0, 2, 4, and 16 days postpartum) were stimulated with PWM (0 and 10 mug/ml) in the presence of RA isomers (9-cis- or 9,13-dicis-RA; 0 to 100 nM), 1,25-(OH)2D3 (0 to 100 nM), or with combinations of these metabolites. The results show that individual isomers of RA had no effect on IFN-gamma secretion by PWM-stimulated MNL from nulliparous or postparturient cows. Furthermore 1,25-dihydroxyvitamin D3 inhibited IFN-gamma secretion by MNL from nulliparous and postparturient dairy cows; however, the degree of inhibition was greater when 9-cis- and 9,13-dicis-RA were also present in the cultures. Finally mononuclear leukocytes from postparturient dairy cows produced substantially less IFN-gamma than did MNL from nulliparous cattle. It is concluded that retinoic acids individually did not affect the capacity of leukocytes from dairy cattle to secrete IFN-gamma. This result is in marked contrast to studies in monogastric species indicating that RAs inhibit IFN-gamma secretion by peripheral blood T cells. Inhibition of IFN-gamma secretion by 1,25-(OH)2D3 was potentiated by 9-cis- and 9,13-di-cis-retinoics acids, suggesting that an excess of dietary vitamins A and D may compromise further the naturally immunosuppressed postparturient dairy cow. Additional research is necessary to determine if the combined effects of these metabolites on IFN-gamma secretion represent an increased susceptibility of the dairy cow to infectious diseases during the periparturient period. Lower secretion of IFN-gamma by MNL from postpartutient dairy cows, relative to nulliparous cattle, suggests that recently-calved cows are naturally immunosuppressed.

Sign in / Sign up

Export Citation Format

Share Document