Influence of mineralogy and moisture content on plasticity and induced anisotropic damage of a claystone; application to nuclear waste disposals

2000 ◽  
Vol 171 (6) ◽  
pp. 621-627 ◽  
Author(s):  
Anne-Sophie Chiarelli ◽  
Beatrice Ledesert ◽  
Malek Sibai ◽  
Mohammed Karami ◽  
Nasser Hoteit
Keyword(s):  
Moisture Content ◽  
Nuclear Waste ◽  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Anisotropic Damage ◽  
Compression Tests ◽  
Two Factors ◽  
Triaxial Compression Tests ◽  
The Way

Abstract The influence of mineralogy and moisture content on mechanical behaviour of a claystone rock is studied by the way of uniaxial and triaxial compression tests and microscopic observations. Some parameters characteristic of phenomena like plasticity and induced anisotropic damage are discussed as a function of these two factors. Rock behaviour becomes more brittle when calcite content grows or when clay or moisture content decreases. At the microlevel, plasticity is induced by slip of clay sheets and induced anisotropic damage appears by growth of oriented microcracks at the interface between grains and matrix.

Behaviour of broken ice as a geomaterial

1991 ◽  
Vol 28 (3) ◽  
pp. 451-457
Author(s):  
T. T. Wong ◽  
N. R. Morgenstern ◽  
D. C. Sego
Keyword(s):  
Key Words ◽  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Phenomenological Approach ◽  
Compression Tests ◽  
Stress Strain ◽  
Broken Ice ◽  
High Plastic ◽  
Triaxial Compression Tests

To study the mechanical behaviour of ice rubble, triaxial compression tests are performed on broken ice samples. Using the phenomenological approach, the stress–strain curves of normally consolidated broken ice are compared and contrasted with those of other geomaterials that display high plastic compressibility. Key words: broken ice, geomaterials, mechanical behaviour, stress–strain curves.

Mechanical Behaviour of Shallow Tunnel in Unsymmetrical Strata

2012 ◽  
Vol 594-597 ◽  
pp. 1210-1213
Author(s):  
Shang Yang Yang
Keyword(s):  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Surrounding Rock ◽  
Shallow Tunnel ◽  
Compression Tests ◽  
Initial State ◽  
Safety Requirements ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Triaxial Compression Tests

Triaxial compression tests have been performed to determine the properties of the surrounding rock. The displacement and stress of surrounding rock have been analyzed according to Silin 2 at Yungui railway under three kinds of conditions: the initial state, excavation without supporting , and supporting after excavation.Plane strain FEM is established to analyze the stability of the surrounding rock. Contrasted the monitor measuring data,the results show that: the most unfavorable position in the tunnel is found at the ridge side of the arch; and the implementation of support to ensure the stability of surrounding rock, and the design of the early support approach to meet the safety requirements. The results have a certain significance for understanding the mechanical behavior of shallow tunnel in unsymmetrical strata

Experimental study of a naturally weathered stiff clay

2016 ◽  
Vol 53 (12) ◽  
pp. 2047-2057 ◽  
Author(s):  
Maria Clorinda Mandaglio ◽  
Nicola Moraci ◽  
Marco Rosone ◽  
Camillo Airò Farulla
Keyword(s):  
Shear Strength ◽  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Experimental Studies ◽  
Water Retention Curve ◽  
Compression Tests ◽  
Weathered Soils ◽  
Wide Range ◽  
Stiff Clay ◽  
Triaxial Compression Tests

Studying the shear strength of a naturally weathered clay is important to understand rain-induced slope failures in weathered soils. However, experimental studies on naturally weathered soils are limited. The paper focuses on the laboratory experimental investigation carried out to analyse the shear strength of a naturally weathered stiff clay that can be found in unsaturated conditions in situ. This has an important practical relevance in the evaluation of the stability conditions of natural slopes at clay outcrops. Different experimental techniques of suction measurement were used to obtain the soil-water retention curve of the clay over a wide range of suctions. Scanning electronic microscope (SEM) observations and results of mercury intrusion porosimetry (MIP) tests are also presented to highlight the considerable fabric arrangement modifications at the microstructural level induced by wetting–drying processes. Moreover, isotropic consolidated drained triaxial compression tests on undisturbed and reconstituted saturated specimens and controlled-suction triaxial compression tests on unsaturated undisturbed specimens were carried out. The test results allowed examination of the saturated mechanical behaviour of clay and comparison of the mechanical behaviour of the saturated material with that in an unsaturated condition.

A Simple Unconsolidated Undrained Triaxial Compression Test Emulator

2015 ◽  
Vol 771 ◽  
pp. 104-107
Author(s):  
Riska Ekawita ◽  
Hasbullah Nawir ◽  
Suprijadi ◽  
Khairurrijal
Keyword(s):  
Triaxial Compression ◽  
Measurement Data ◽  
Radial Strain ◽  
Compression Tests ◽  
Viscous Effects ◽  
Axial Pressure ◽  
Strain Stress ◽  
The University ◽  
And Storage ◽  
Triaxial Compression Tests

An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

scholarly journals Semi-empirical elastic–thermoviscoplastic model for clay

2016 ◽  
Vol 53 (10) ◽  
pp. 1583-1599 ◽  
Author(s):  
David Kurz ◽  
Jitendra Sharma ◽  
Marolo Alfaro ◽  
Jim Graham
Keyword(s):  
Stress Level ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Compression Tests ◽  
One Dimensional ◽  
Load Duration ◽  
Compression Creep ◽  
Overconsolidated Clays ◽  
Semi Empirical ◽  
Triaxial Compression Tests

Clays exhibit creep in compression and shear. In one-dimensional compression, creep is commonly known as “secondary compression” even though it is also a significant component of deformations resulting from shear straining. It reflects viscous behaviour in clays and therefore depends on load duration, stress level, the ratio of shear stress to compression stress, strain rate, and temperature. Research described in the paper partitions strains into elastic (recoverable) and plastic (nonrecoverable) components. The plastic component includes viscous strains defined by a creep rate coefficient ψ that varies with plasticity index and temperature (T), but not with stress level or overconsolidation ratio (OCR). Earlier elastic–viscoplastic (EVP) models have been modified so that ψ = ψ(T) in a new elastic–thermoviscoplastic (ETVP) model. The paper provides a sensitivity analysis of simulated results from undrained (CIŪ) triaxial compression tests for normally consolidated and lightly overconsolidated clays. Axial strain rates range from 0.15%/day to 15%/day, and temperatures from 28 to 100 °C.

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