Coal Strength Development with the Increase of Lateral Confinement
Abstract
:1. Introduction
2. Sample Information and Description
3. Sampling and Experimental Procedure
3.1. Specimen Preparation
3.2. Triaxial Compressive Test Set-Up and Procedure
4. Results
4.1. Stress-Strain Curves
4.2. Failure Mode
4.3. Confinement-Dependent Strength Behavior
4.4. Failure Envelope
5. Discussion
5.1. Mechanism of Strength Enhancement
5.2. Strength Characterization
6. Conclusions
Author Contributions
Funding
Conflicts of Interest
List of symbols:
UCS | Uniaxial compressive strength |
εv | Volumetric strain |
εc | Circumferential strain |
εa | Axial strain |
Volume change | |
V0 | Initial volume |
σ1 | Major principal stress |
σ3 | Minor principal stress/confining stress |
c | Cohesion |
ϕ | Internal friction angle |
m | Empirical parameter in Hoek-Brown criterion |
s | Empirical parameter in Hoek-Brown criterion |
a | constant in Hoek-Brown criterion |
ACS | Apparent uniaxial compressive strength |
C | Constant |
k2 | Slope of the linear fit of UCS to high confinement data |
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Specimen Numbering | Confining Stress (MPa) | Axial Loading Rate (mm/min) | Diameter (mm) | Height (mm) | Note |
---|---|---|---|---|---|
1-1 | 0.25 | 0.15 | 49.00 | 100.00 | Group 1 |
1-2 | 0.25 | 0.15 | 49.91 | 100.00 | Group 2 |
2-1 | 0.5 | 0.15 | 49.05 | 100.00 | Group 1 |
2-2 | 0.5 | 0.15 | 49.35 | 100.00 | Group 2 |
3-1 | 1.00 | 0.15 | 49.55 | 100.00 | Group 1 |
3-2 | 1.00 | 0.15 | 49.39 | 100.00 | Group 2 |
4-1 | 2.00 | 0.15 | 48.66 | 100.00 | Group 1 |
4-2 | 2.00 | 0.15 | 49.55 | 100.00 | Group 2 |
5-1 | 3.00 | 0.15 | 49.2 | 100.03 | Group 1 |
5-2 | 3.00 | 0.15 | 49.39 | 100.00 | Group 2 |
6-1 | 4.00 | 0.15 | 49.63 | 100.00 | Group 1 |
6-2 | 4.00 | 0.15 | 49.35 | 100.00 | Group 2 |
7-1 | 5.00 | 0.15 | 49.29 | 100.00 | Group 1 |
7-2 | 5.00 | 0.15 | 49.56 | 100.02 | Group 2 |
8-1 | 6.00 | 0.15 | 49.40 | 100.00 | Group 1 |
8-2 | 6.00 | 0.15 | 49.30 | 100.02 | Group 2 |
9-1 | 7.00 | 0.15 | 49.59 | 100.00 | Group 1 |
9-2 | 7.00 | 0.15 | 49.43 | 100.00 | Group 2 |
10-1 | 8.00 | 0.15 | 49.80 | 100.00 | Group 1 |
10-2 | 8.00 | 0.15 | 49.70 | 100.00 | Group 2 |
Micro Parameters | Value |
---|---|
Particle density (kg/m3) | 1960 |
Effective modulus (GPa) | 1.0 |
Normal-to-shear stiffness ratio | 1.5 |
Friction coefficient | 0.4 |
Gap interval | 0.0 |
Radius multiplier | 1.0 |
Bond effective modulus (GPa) | 1.0 |
Bond effective modulus (GPa) | 1.5 |
Moment contribution factor | 1.0 |
Tensile strength (MPa) | 10.0 |
Cohesion (MPa) | 40.0 |
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Zhang, J.; Li, Y. Coal Strength Development with the Increase of Lateral Confinement. Energies 2019, 12, 405. https://doi.org/10.3390/en12030405
Zhang J, Li Y. Coal Strength Development with the Increase of Lateral Confinement. Energies. 2019; 12(3):405. https://doi.org/10.3390/en12030405
Chicago/Turabian StyleZhang, Junwen, and Yulin Li. 2019. "Coal Strength Development with the Increase of Lateral Confinement" Energies 12, no. 3: 405. https://doi.org/10.3390/en12030405