Digital Rock Mechanical Properties by Simulation of True Triaxial Test: Impact of Microscale Factors
Abstract
:1. Introduction
2. Materials and Methods
2.1. Mathematical Model
2.2. Physical Model
3. Results and Discussion
3.1. Model Validation
3.2. Sensitivity Analysis
3.2.1. Particle Size
3.2.2. Fracture Morphology
3.2.3. Clay Content
4. Conclusions
- The simulation method can simulate the true triaxial experiment well and is in good agreement with the experimental results;
- The stress at the contact surface is large, which becomes the mechanical weak link prone to failure. The porosity decreases with the increase in stress and has a good linear relationship. However, when the particle model volumetric strain is between 0.0108 and 0.0157, the pore and throat parameters will change abruptly. When the particle size is small, the rock strength is higher and more sensitive;
- When the fracture angle is between 45° and 75°, the fracture has a great influence on the peak stress. The angle between the natural fracture and the fracturing direction should be less than 45° as much as possible. Sharper fracture edges are more prone to fracture propagation;
- Clay affects the rock strength by influencing the force chains formed by the rock skeleton. The peak stress is gradually decreased with the increase in the content of clay, but the influence of different types of clay is different. Fracturing is easier when the structural clay content is higher than 25%. It is easier to fracture in a direction parallel to the laminated clay when the clay content is below 27%. Conversely, the direction perpendicular to the laminated clay rocks is better.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Parameter | Numerical Value | Description |
---|---|---|
10 mm | Diameter of sample | |
30 GPa | Young’s modulus | |
0.3 | Poisson’s ratio | |
2.5 g/cm3 | Density of sample | |
20 MPa | Cohesion | |
35° | Angle of internal friction |
Case No. | Case 1 | Case 2 | Case 3 | Case 4 | Case 5 | Case 6 | Case 7 |
---|---|---|---|---|---|---|---|
Particle size (mm) | 2 | 1 | 0.5 | 0.25 | 0.125 | 0.0625 | 0.01 |
Case | Geometric Parameters of Prefabricated Fractures | |
---|---|---|
Quantification | Variable | |
Fracture angle | b = 1 | α = 0°, 15°, 30°, 45°, 60°, 75°, 90° |
Fracture aperture | α = 60° | b = 0.01 mm, 0.1 mm, 0.5 mm, 1 mm, 2 mm |
Parameter | Numerical Value | Description |
---|---|---|
10 mm | Diameter of particle | |
23 GPa | Young’s modulus of clay | |
0.34 | Poisson’s ratio of clay | |
2.55 g/cm3 | Density of clay | |
10 MPa | Cohesion of clay | |
30° | Angle of internal friction of clay |
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Ma, W.; Yang, Y.; Yang, W.; Lv, C.; Yang, J.; Song, W.; Sun, H.; Zhang, L.; Zhang, K.; Yao, J. Digital Rock Mechanical Properties by Simulation of True Triaxial Test: Impact of Microscale Factors. Geotechnics 2023, 3, 3-20. https://doi.org/10.3390/geotechnics3010002
Ma W, Yang Y, Yang W, Lv C, Yang J, Song W, Sun H, Zhang L, Zhang K, Yao J. Digital Rock Mechanical Properties by Simulation of True Triaxial Test: Impact of Microscale Factors. Geotechnics. 2023; 3(1):3-20. https://doi.org/10.3390/geotechnics3010002
Chicago/Turabian StyleMa, Wenjie, Yongfei Yang, Wendong Yang, Changran Lv, Jiangshan Yang, Wenhui Song, Hai Sun, Lei Zhang, Kai Zhang, and Jun Yao. 2023. "Digital Rock Mechanical Properties by Simulation of True Triaxial Test: Impact of Microscale Factors" Geotechnics 3, no. 1: 3-20. https://doi.org/10.3390/geotechnics3010002