Stress–strain response of Cold Lake oil sands

1993 ◽  
Vol 30 (2) ◽  
pp. 220-235 ◽  
Author(s):  
R. C. K. Wong ◽  
W. E. Barr ◽  
P. R. Kry
Keyword(s):  
Pore Pressure ◽  
Critical State ◽  
Oil Sands ◽  
Void Ratio ◽  
Stress Path ◽  
Strain Response ◽  
Oil Sand ◽  
Stress Strain ◽  
Sample Disturbance ◽  
Cold Lake

The stress–strain response of Cold Lake oil sands at confining stresses and temperatures up to 18 MPa and 200 °C, respectively, was studied in a triaxial apparatus using 89-mm full diameter cores. Tests that have been performed include conventional triaxial tests such as hydrostatic compression, initial Young's modulus determination, and cyclic drained and undrained compression. Tests involving pore-pressure increase and decrease under constant total stresses were also performed to simulate the stress path encountered in the field during the cyclic steam stimulation process. Treating oil sand as a particulate medium, possible modes of granular interaction were explored for all tests along different stress paths. Four modes of granular interaction were identified: (i) contact elastic deformation, (ii) rolling, (iii) shear dilation, and (iv) crushing. These modes provide a useful framework for explaining the behaviour arising from the effects of variation in void ratio owing to sample disturbance, stress level, stress path, induced anisotropy, and temperature. Other behaviour relating to critical state, localized shear deformation, and load–unload–reload are also examined. Key words : oil sand, stress, strain, void ratio, pore pressure, temperature, mode of granular interaction, critical state.

Void Ratio Effects on the Hyperbolic Stress-Strain Response of a Sand

2009 ◽  
pp. 250-250-8 ◽  
Author(s):  
RL Kondner ◽  
JS Zelasko
Keyword(s):  
Void Ratio ◽  
Strain Response ◽  
Stress Strain

Measurement of hydraulic conductivity in oil sand tailings slurries

1996 ◽  
Vol 33 (4) ◽  
pp. 642-653 ◽  
Author(s):  
Nagula N Suthaker ◽  
J Don Scott
Keyword(s):  
Hydraulic Conductivity ◽  
Oil Sands ◽  
Void Ratio ◽  
Large Strain ◽  
Measurement Techniques ◽  
Hydraulic Gradient ◽  
Oil Sand ◽  
Fines Content ◽  
Acid Lime ◽  
Clamping Device

Fine tails, the resulting fine waste from oil sand processing, undergoes large-strain consolidation in tailings ponds. Its consolidation behaviour must be analyzed using a large-strain consolidation theory, which requires the determination of the relationship between the void ratio and hydraulic conductivity. Conventional measurement techniques are not suitable for fine tails, and a special slurry consolidometer, with a clamping device to prevent seepage-induced consolidation, was designed to determine the hydraulic conductivity of the fine tails and nonsegregating fine tails – sand slurries. The hydraulic conductivity of slurries is not constant but decreases with time to a steady-state value. Hydraulic conductivity is also influenced by the hydraulic gradient and bitumen content. It is shown that a low hydraulic gradient, less than 0.2, is necessary to counteract the effect of the bitumen and to represent tailings pond conditions. The hydraulic conductivity of fine tails – sand mixes is controlled by the fines void ratio, hence, fines content. The hydraulic conductivity of chemically amended nonsegregating tailings can be lower than that of fine tails. However, acid–lime or acid – fly ash amended nonsegregating tailings have similar hydraulic conductivity values in terms of fines void ratio. The hydraulic conductivity of nonsegregating tailings appears to be governed by fines content and by the nature of the fines aggregation caused by the chemical additive. Key words: tailings, slurries, hydraulic conductivity, slurry consolidometer, nonsegregating tailings, oil sands.

Shear strength and stress—strain behaviour of Athabasca oil sand at elevated temperatures and pressures

1987 ◽  
Vol 24 (1) ◽  
pp. 1-10 ◽  
Author(s):  
J. G. Agar ◽  
N. R. Morgenstern ◽  
J. D. Scott
Keyword(s):  
Shear Strength ◽  
Oil Sands ◽  
Elevated Temperatures ◽  
Triaxial Compression ◽  
Substantial Reduction ◽  
Hyperbolic Model ◽  
Oil Sand ◽  
Hydrocarbon Gases ◽  
Stress Strain ◽  
Strain Behaviour

The results of a series of triaxial compression tests on undisturbed samples of Athabasca oil sand at elevated temperatures ranging from 20 to 200 °C are summarized. The material tested had experienced gradual unloading and depressurization as a result of erosion in the Saline Creek valley near Fort McMurray. More deeply buried oil sands are known to contain much higher concentrations of dissolved hydrocarbon gases in the pore fluids. The measured shear strength of Athabasca oil sand did not change significantly as a result of the increased temperatures that were applied. The strength of Athabasca oil sand (at 20–200 °C) was found to be greater than comparable shear strengths reported for dense Ottawa sand (at 20 °C). Although heating to 200 °C had little effect on shear strength, it is recognized that pore pressure generation during undrained heating may cause substantial reduction of the available shearing resistance, particularly in gas-rich oil sands. The experimental data were used to investigate the influence of such factors as stress path dependency, microfabric disturbance, and heating to elevated temperatures on the shear strength and stress–strain behaviour of oil sand. Curve fitting of the test data suggests that the hyperbolic model is a useful empirical technique for stress—deformation analyses in oil sands. Hyperbolic stress—strain parameters derived from the experimental results for Athabasca oil sand are presented. Key words: oil sand, Athabasca oil sand, tar sand, shear strength, stress, strain, deformation, heating, high temperature, elevated temperatures, high pressure, elevated pressure, thermal properties, drained heating, undrained heating, triaxial compression testing.

Undrained and drained (?) stress-strain response

2000 ◽  
Vol 37 (5) ◽  
pp. 1126-1130 ◽  
Author(s):  
Y P Vaid ◽  
A Eliadorani
Keyword(s):  
Effective Stress ◽  
Void Ratio ◽  
Effective Strain ◽  
Shear Stiffness ◽  
Stress Path ◽  
Stress Increment ◽  
Stress Strain ◽  
Field Problem ◽  
Deformation Response ◽  
Do So

The deformation response of saturated soils to a total stress increment at the ambient void ratio and effective stress state is shown to be dependent on the direction of the effective strain increment. It is argued that in a given field problem, most soil elements neither deform fully drained nor undrained, but do so partially drained. The degree of partial drainage controls the direction of the effective stress increment and hence the deformation response. Experimental data are presented which demonstrate how shear stiffness changes with the direction of effective stress increment as a function of the ambient effective stress state.Key words: stress-strain, undrained, drained, partially drained, stress path, stiffness.

scholarly journals Influential Factors of the Static Shear Properties of Coral Mud in the South China Sea

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Yang Shen ◽  
Xiaoxi Rui ◽  
Long Yang ◽  
Shaoyu Li ◽  
Xue Shen
Keyword(s):  
South China Sea ◽  
Pore Pressure ◽  
South China ◽  
Void Ratio ◽  
Confining Pressure ◽  
Stress Path ◽  
The South China Sea ◽  
Initial Void Ratio ◽  
Static Shear ◽  
Cam Clay

Coral mud, a kind of special material used for constructing islets in reclamation projects, is widely spread in the South China Sea. Combined with microstructure research, a series of triaxial tests were performed in this paper to study the static shear strength characteristics and potential factors that can influence them. The effective stress path was similar to the total stress path because of the unique microstructure resulting in a high strength and a high dissipation rate of the pore pressure in the coral mud. The initial void ratio and the initial confining pressure affected the strength and deformation characteristics of the coral mud. When the soil came to failure, the pore pressure coefficient Af varied linearly with the initial void ratio. The critical friction angle was greatly influenced by the confining pressure, and its magnitude first developed to a peak value and then decreased as the void ratio increased. This change showed that there was a linear relationship between the initial elastic modulus E0i and lgp0 as well as between the secant modulus E50 and p0. The estimation ability of Cam-Clay was verified in this research. The value of parameter λ was determined incrementally by a larger initial void ratio, while the value of parameter M decreased smoothly first and then rose slightly; the selection of parameter κ was approximately 0.0035. The results supported that the Cam-Clay model is able to simulate the stress-strain relationship of coral mud, and a referenced estimation can be reliably and efficiently obtained for the reclamation projects of constructing islets.

Thermal expansion and pore pressure generation in oil sands

1986 ◽  
Vol 23 (3) ◽  
pp. 327-333 ◽  
Author(s):  
J. G. Agar ◽  
N. R. Morgenstern ◽  
J. D. Scott
Keyword(s):  
Thermal Expansion ◽  
Pore Pressure ◽  
Oil Sands ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Oil Sand ◽  
Thermal Expansion Coefficients ◽  
Stress Changes ◽  
Expansion Coefficients

The prediction of stress changes and deformations arising from ground heating requires the coupled solution of the heat transfer and consolidation equations. Heat consolidation as a class of problems is distinct from other thermally induced consolidation problems involving processes such as frost heave and thaw consolidation in that it involves heating to elevated temperatures well above normal ground temperatures. Two of the important parameters required in analyses of heat consolidation problems are thermal expansion coefficients and a coefficient of thermal pore pressure generation.Relationships describing thermal expansion behaviour and thermal pore pressure generation in oil sands are presented. Both drained and undrained thermal expansion coefficients for Athabasca oil sand were determined by means of heating experiments in the temperature range 20–300 °C. The thermal pore pressure generation coefficient was evaluated in undrained heating experiments under constant total confining stresses and under constant effective confining stresses. The equipment and experimental methods developed during this study are appropriate for determination of thermal expansion and pore pressure generation properties of oil sands and other unconsolidated geologic materials. Key words: thermal expansion, oil sand, tar sand, thermal pore pressure generation, heat consolidation, thermal consolidation, coefficient of thermal expansion, thermal stresses, ground heating, thermally enhanced oil recovery, thermoelasticity, undrained heating.

Experimental Characterization of Mechanical Behavior of Cord-Rubber Composites

1982 ◽  
Vol 10 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. Kumar ◽  
C. W. Bert
Keyword(s):  
Response Characteristic ◽  
Cord Compression ◽  
Complete Characterization ◽  
Strain Response ◽  
Strain Gages ◽  
Experimental Characterization ◽  
Rubber Composites ◽  
Stress Strain ◽  
Strain Data

Abstract Unidirectional cord-rubber specimens in the form of tensile coupons and sandwich beams were used. Using specimens with the cords oriented at 0°, 45°, and 90° to the loading direction and appropriate data reduction, we were able to obtain complete characterization for the in-plane stress-strain response of single-ply, unidirectional cord-rubber composites. All strains were measured by means of liquid mercury strain gages, for which the nonlinear strain response characteristic was obtained by calibration. Stress-strain data were obtained for the cases of both cord tension and cord compression. Materials investigated were aramid-rubber, polyester-rubber, and steel-rubber.

Stress Path Dependent Hydromechanical Properties of Carbonates - Impact of Heterogeneities and use of Effective Medium Theory for Critical State Scaling

2009 ◽  
Author(s):  
Nicolas F. Gland ◽  
Jeremie Dautriat ◽  
Olga Vizika ◽  
Alexandre Dimanov ◽  
Jean L. Raphanel
Keyword(s):  
Critical State ◽  
Effective Medium Theory ◽  
Stress Path ◽  
Effective Medium ◽  
Medium Theory ◽  
Path Dependent
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