Some aspects of the compressibility behaviour of a clayey sand

2001 ◽  
Vol 38 (6) ◽  
pp. 1177-1186 ◽  
Author(s):  
Flavia Burmeister Martins ◽  
Luiz Antônio Bressani ◽  
Matthew Richard Coop ◽  
Adriano Virgilio Damiani Bica
Keyword(s):  
Published Data ◽  
Clayey Sand ◽  
One Dimensional ◽  
Sand Mixture ◽  
Oedometer Tests ◽  
Compression Line ◽  
Normal Compression

The intrinsic behaviour of a residual clayey sand derived from sandstone was investigated in one-dimensional compression. The data show some interesting differences when compared with other published data, in that no unique normal compression line can be identified. Although the compressibility on first loading is similar to that for many sandy materials at states on their normal compression lines, the locations of the compression curves were found to be a function of the initial voids ratio, and there was no convergence at higher stresses. Tests on a model clay-sand mixture indicated that this behaviour is common to gap-graded clayey sands.Key words: sands, compressibility, oedometer tests.

scholarly journals High-density bimodal bentonite blends for hydraulic sealings at the Ibbenbüren coalmine

Clay Minerals ◽  
2015 ◽  
Vol 50 (3) ◽  
pp. 391-403 ◽  
Author(s):  
Felicitas Wolters ◽  
Wiebke Baille ◽  
Katja Emmerich ◽  
Eva Schmidt ◽  
Christian Wolters ◽  
...  
Keyword(s):  
Swelling Pressure ◽  
Mining Area ◽  
Applied Strain ◽  
Sand Mixture ◽  
Pressure Tests ◽  
Pressure Development ◽  
Pressure Water ◽  
Sufficient Magnitude ◽  
Sealing Materials ◽  
Oedometer Tests

AbstractThe two high-pressure water-retaining dams at the Ibbenbüren coalmine in Münsterland (Germany) have to perform reliably under the induced tension caused by further exploitation of the current mining area. The load-bearing and the sealing functions of the new barriers were separated and new sealing materials were developed. An innovative multilayer sealing system of bentonite and sandwiched equipotential layers (SANDWICH) supporting homogeneous swelling and sealing, independent of formation water (Nüesch et al., 2002), was applied in this project. A testing program of strain-controlled swelling pressure tests on compacted bentonite specimens and on a bentonite/sand mixture was conducted to ensure an adequate potential for swelling-pressure development.The measurements under constant volume for dry densities between 1.45 g/cm3 and 1.67 g/cm3 showed an evolving swelling pressure between 1.04 and 1.8 MPa for 100% bentonite samples. Straincontrolled oedometer tests for zero strain and step-wise applied strain up to 2% revealed that a sufficient magnitude of swelling pressure existed at maximum applied strain.

scholarly journals Mechanical behaviour of Panzhihua iron tailings

2019 ◽  
Vol 56 (3) ◽  
pp. 420-435 ◽  
Author(s):  
W. Li ◽  
M.R. Coop
Keyword(s):  
High Risk ◽  
Rate Of Convergence ◽  
Mechanical Behaviour ◽  
Critical State ◽  
Preparation Method ◽  
Tailings Impoundment ◽  
Tailings Dams ◽  
Different Shapes ◽  
Compression Line ◽  
Normal Compression

Safety problems have concerned many researchers studying tailings dams in recent years, as they have a high risk of failure due to liquefaction. Existing analysis of liquefaction in tailings within a critical state framework has relied on the critical state line (CSL) being unique in the volumetric plane. However, recent advances have highlighted a so-called “transitional” behaviour in which the location of the normal compression line (NCL) and CSL is a function of the density of the soils at deposition. This paper presents a detailed investigation of the mechanics of tailings taken from three locations of an iron tailings impoundment. Reconstituted samples were prepared by different methods and at different densities. No transitional behaviour was found, although the results show that the rate of convergence of the compression curves changes, with the finest pond material reaching a unique NCL earliest. The preparation method was found not to have a large effect on the behaviour for these tailings. Unique CSLs could be clearly identified for all the three tailings, but with different shapes, giving rise to a changing susceptibility to liquefaction. This susceptibility tends to increase from the pond to the upper beach.

Application of Terzaghi's consolidation theory to nearly saturated soils

1994 ◽  
Vol 31 (2) ◽  
pp. 311-317 ◽  
Author(s):  
Hans H. Vaziri ◽  
Harold A. Christian
Keyword(s):  
Unsaturated Soils ◽  
Measured Data ◽  
One Dimensional ◽  
Deformation Response ◽  
Consolidation Theory ◽  
Modified Equations ◽  
Consolidation Coefficient ◽  
Soil Skeleton ◽  
Oedometer Tests ◽  
Compressibility Characteristics

Terzaghi's one-dimensional consolidation theory is modified to account for the compressibility of fluid and solid phases. The proposed modified equations can be used to analyze the consolidation response of unsaturated soils over the saturation range where the gases remain in an occluded form (generally within a range between 80 and 100aturation); however, such applications are subject to the same limitations and idealizations implicit in Terzaghi's classical consolidation theory. The purpose of this note, therefore, is to offer a simple solution and not to unravel the complexities involved in general analysis of flow and deformation response of unsaturated soils. The proposed approach involves defining the consolidation coefficient, and hence the time factor, in terms of an equivalent fluid compressibility. This equivalent fluid is assumed to represent the compressibility characteristics of all the compressible phases that constitute the soil skeleton. The proposed generalized form of Terzaghi's consolidation equations is shown to qualitatively capture the consolidation behaviour of unsaturated soils. To test the validity of the formulations presented, one-dimensional oedometer tests were performed on specimens of Lantz clay that had been prepared at different saturation levels; satisfactory agreement was achieved between the theoretical and measured data at two states of saturation. Key words : consolidation, theoretical solutions, oedometer test, compressible fluid, occluded gas.

Experiment Study on One Dimensional Vertical Soil Pole Seeper Infiltration of Unsaturated Clayey Sand

2011 ◽  
Vol 250-253 ◽  
pp. 3785-3789
Author(s):  
Qiang Qiang Miao ◽  
Zheng Han Chen ◽  
Qing Qing Zhu ◽  
Zhi Hua Yao ◽  
Jun Hao Zhang
Keyword(s):  
High Water ◽  
Measuring System ◽  
High Water Content ◽  
Dry Density ◽  
Experiment Study ◽  
Time Pass ◽  
Clayey Sand ◽  
One Dimensional ◽  
Water Head ◽  
The Relationship

Measuring system of soil moisture and water bedload LGD-Ⅲ was used in those tests . Infiltration law of one dimensional vertical soil poles were carried out profound studies,under different density and a constant water head . At the same time,the course of wetness front along with time pass away, infiltration law along with time pass away and different high water content along with time pass away were made a comprehensive studies , under different dry density. According to a great deal of test data, the relationship between wetness front and time was given to a function under different dry density.

scholarly journals An elastic-viscous-plastic structured UH model

2021 ◽  
Vol 248 ◽  
pp. 01033
Author(s):  
Zhu Enyang ◽  
Wang Yihe
Keyword(s):  
Test Data ◽  
Soil Structure ◽  
Model Simulation ◽  
Time Effect ◽  
Plastic Strains ◽  
Time Effects ◽  
Hardening Model ◽  
Combined Actions ◽  
Compression Line ◽  
Normal Compression

On the basis of the structured unified hardening model (structured UH model) considering soil structured collapse, the time effect is take into account, and an elastic-viscous-plastic structured UH model is extended. In the presented model, the moving normal compression line (MNCL) is extended to a moving instant normal compression line (MINCL) for simulating both soil structure effect and time effect. Then the instance plastic strains irrespective of time effect are calculated by referring the MINCL, and the plastic strains due to time effect are calculated by referring the traditional instant normal compression line. Comparisons between test data and model simulation indicate that the presented elastic-viscous-plastic structured UH model is qualified to simulate the combined actions of soil structure and time effects both in compression and in shearing.

scholarly journals Influence of structure on the behavior of a saturated clayey loess

2016 ◽  
Vol 53 (6) ◽  
pp. 1026-1037 ◽  
Author(s):  
L. Xu ◽  
M.R. Coop
Keyword(s):  
Chinese Loess Plateau ◽  
Triaxial Tests ◽  
Scanning Electron Micrographs ◽  
Soil Behavior ◽  
Chinese Loess ◽  
Southern Chinese ◽  
Reconstituted Soil ◽  
Very High ◽  
Oedometer Tests ◽  
Compression Line

An intensive experimental investigation by means of triaxial and oedometer tests was performed on a clayey loess that was retrieved from two depths at a location on the southern Chinese Loess Plateau. Intact and reconstituted samples were used to identify the effects of the natural structure on soil behavior in saturated conditions. The behavior in compression was clearly affected by structure with the intact samples reaching well-defined gross yield points outside the intrinsic compression line of the reconstituted soil, after which the compression paths converged towards the intrinsic compression lines, behavior which is consistent with destructuration. However, very high stresses were required to give complete convergence. Similarly the triaxial tests that were carried out at lower stress levels also did not give convergence of the critical states so that different critical state lines could be defined for the intact and reconstituted soils. This was consistent with qualitative observations from scanning electron micrographs that natural elements of fabric and possibly bonding persisted even after triaxial shearing. The effects of structure at the two depths on the compression and shearing behavior were slightly larger for the shallower samples. Despite the very different genesis of the soils, it was found that similar frameworks could be applied to those used for sedimentary clays and that the degree of structure was equivalent to a clay of medium sensitivity.

Quantification of the effects of structure on the compression of a stiff clay

2008 ◽  
Vol 45 (9) ◽  
pp. 1324-1334 ◽  
Author(s):  
A. Gasparre ◽  
M. R. Coop
Keyword(s):  
Natural Soil ◽  
Compression Behaviour ◽  
Sample Depth ◽  
Stiff Clay ◽  
Loading And Unloading ◽  
London Clay ◽  
Intact Soil ◽  
Very High ◽  
Oedometer Tests ◽  
Compression Line

A detailed analysis was made of the compression behaviour of London Clay from oedometer tests, investigating the effects of the clay structure through comparisons between the behaviour of the intact soil and that of the same soil in a reconstituted state. The normalizing parameters commonly used in the literature to analyze the effects of structure on the compression behaviour of clays were found not to represent accurately the real behaviour of those clays that have a gradual yield in compression and require very high stresses to reach and cross the intrinsic compression line. For these soils, it is often difficult to identify a clear yield stress and the effects arising from the structure of the intact material may be concealed by the effects arising from the sample depth and the curvature of the intrinsic compression line at high stresses. A new normalizing parameter is introduced that refers the compression of the natural soil to the intrinsic swelling behaviour and the intrinsic compression line of the material. This was found to better represent the enhanced resistance of the intact material in compression while not requiring numerous loading and unloading stages in the oedometer tests as required by other methods.

Analytical Solution of Chamber Effective Length in the Axial Engine

2009 ◽  
Author(s):  
S. R. Dehghani ◽  
A. A. Mozafari ◽  
M. H. Saidi ◽  
A. Ghafourian
Keyword(s):  
Integral Equation ◽  
Effective Length ◽  
Published Data ◽  
Vaporization Rate ◽  
Initial State ◽  
Related Equation ◽  
One Dimensional ◽  
Dimensionless Velocity ◽  
Definition Of ◽  
Complex Integral

In this research, effective length of one-dimensional combustion in a dilute monopropellant spray, constant area and fixed volume chamber is analytically predicted. A new evaporation rate in the form of dk+1 relation is introduced. In the case of controlling vaporization by radiative heat transfer, k is equal to zero, and when molecular processes control the vaporization, k will be equal to one and in some cases vaporization data need the value of k greater than one to fit properly to related equation. Development of this approach can be used in the design of combustion chambers with optimum length and with using vaporization rate of R = R0〈r〉0k/〈r〉k. Spray equation and distribution function in one-dimensional coordinate in direction of chamber axis is used as the governing equation. Multiplying velocity and displacement variables by simplified spray equation and some manipulation lead to a final form of integral equation. Definition of β1β3 as criteria will simplify the complex integral equation to a solvable relation. Results provide dimensionless velocity of droplets (from initial state to completely vaporization) and chamber effective length for various values of k. The results obtained by employing dk+1 relation show that increasing k increases in droplet vaporization rate as well as oxidizer velocity and decreases in dimensionless effective length of chamber. Also they show that for β1β3 ≥ 25 deviation of dimensionless velocity from published data by Dehghani et al. (2009) is less than 3%.

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.

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