Study on the Dynamic Evolution of Mining-Induced Stress and Displacement in the Floor Coal-Rock Induced by Protective Layer Mining
Abstract
:1. Introduction
2. Similar Experiments of Upper Protective Layer Mining
2.1. Similarity Theory
2.1.1. Laws of Similarity
2.1.2. Similarity Criterion
2.2. Geological Background
2.3. Similarity Experiment
2.4. Experiment Method
3. Numerical Simulation Description
3.1. Overview for Numerical Simulation
3.2. Numerical Model
4. Experiment Results
4.1. Movement Characteristic
4.2. Deformation Characteristics of Protected Layer
4.3. Stress Characteristics of Protected Layer
5. Numerical Simulation Results
5.1. Analysis of Stress Characteristics During the Protective Layer Mining
5.2. Analysis of the Deformation
6. Discussion
7. Conclusions
- Through similarity simulation experiments, the maximum strike expansion deformation rate is 11.3‰ in the 9# coal seam after the mining of the 82# coal seam. Stress monitoring during the protective layer mining reveals that the stress concentration zone is within 32 m ahead of the working face, the original stress zone is beyond 32 m ahead of the working face, the stress relief zone is within 51 m behind the working face, and the stress recovery zone is beyond 51 m behind the working face.
- Through FLAC3D numerical simulation, it can be concluded that the vertical stress of the underlying mass is reduced due to the mining of the protective layer. The reduction rate of vertical stress gradually increases as the working face advances, reaching up to 99.6%. The stress concentration zone gradually forms and enlarges in front of the goaf and behind the open-off cut. The displacement and deformation of the underlying mass is affected by the protective layer mining, forming a funnel-shaped displacement above the goaf and a semicircular displacement below. The displacement increases gradually as the working face advances; eventually the displacement of the roof and floor is symmetrically distributed, and the maximum expansion deformation in the upper goaf reaches 15.6 mm. The pressure relief effect is exerted on the underlying 9# coal seam after the mining of the 82# coal seam, with an average pressure relief rate of 86.2%, demonstrating a good pressure relief effect.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Lithology | Thickness/cm | Total Weight/kg | Accumulated Thickness/cm | Ration Number | Sand/kg | Calcium Carbonate/kg | Gypsum/kg | Water/kg |
---|---|---|---|---|---|---|---|---|
Mudstone | 10.0 | 150 | 149.0 | 473 | 90.00 | 15.75 | 6.75 | 16.7 |
Fine sandstone | 23.0 | 345 | 139.0 | 437 | 207.00 | 15.53 | 36.23 | 38.3 |
Mudstone | 4.0 | 60 | 116.0 | 473 | 36.00 | 6.30 | 2.70 | 6.7 |
7# coal seam | 3.7 | 55.5 | 112.0 | 773 | 36.38 | 3.60 | 1.58 | 6.2 |
Mudstone | 2.0 | 30 | 108.3 | 473 | 18.00 | 3.15 | 1.35 | 3.3 |
Fine sandstone | 29.0 | 435 | 106.3 | 437 | 261.00 | 19.58 | 45.68 | 48.3 |
Mudstone | 2.0 | 30 | 77.3 | 473 | 18.00 | 3.15 | 1.35 | 3.3 |
82# coal seam | 1.8 | 27 | 75.3 | 773 | 17.70 | 1.80 | 0.75 | 3.0 |
Mudstone | 3.0 | 45 | 73.5 | 473 | 27.00 | 4.73 | 2.03 | 5.0 |
Fine sandstone | 7.5 | 112.5 | 70.5 | 437 | 67.50 | 5.06 | 11.81 | 12.5 |
Medium sandstone | 2.0 | 30 | 63.0 | 437 | 18.00 | 1.35 | 3.15 | 3.3 |
9# coal seam | 2.0 | 30 | 61.0 | 773 | 19.73 | 1.95 | 0.83 | 3.3 |
Mudstone | 4.0 | 60 | 59.0 | 473 | 36.00 | 6.30 | 2.70 | 6.7 |
Fine sandstone | 18.0 | 270 | 55.0 | 437 | 162.00 | 12.15 | 28.35 | 30.0 |
Medium sandstone | 3.0 | 45 | 37.0 | 437 | 27.00 | 2.03 | 4.73 | 5.0 |
Mudstone | 8.0 | 120 | 34.0 | 473 | 72.00 | 12.60 | 5.40 | 13.3 |
Fine sandstone | 26.0 | 390 | 26.0 | 437 | 234.00 | 17.55 | 40.95 | 43.3 |
Lithology | Density (kg/m3) | Volume Modulus (GPa) | Shear Modulus (GPa) | Cohesion (MPa) | Internal Friction Angle (°) | Tensile Strength (MPa) |
---|---|---|---|---|---|---|
Fine sandstone | 2500 | 16.7 | 17 | 6.8 | 40 | 3.8 |
Medium sandstone | 2560 | 17 | 14 | 5.1 | 39 | 3.6 |
Siltstone | 2500 | 8.3 | 6.25 | 3.5 | 37 | 1.5 |
82# coal seam | 1400 | 4.91 | 2.01 | 1.25 | 32 | 0.15 |
9# coal seam | 1400 | 4.91 | 2.01 | 1.25 | 32 | 0.15 |
Mudstone | 2430 | 9.5 | 6.6 | 0.85 | 36 | 1.6 |
Aluminum mudstone | 2483 | 9.97 | 7.35 | 1.2 | 32 | 0.58 |
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Liu, C.; Man, Z.; Li, M. Study on the Dynamic Evolution of Mining-Induced Stress and Displacement in the Floor Coal-Rock Induced by Protective Layer Mining. Minerals 2024, 14, 1084. https://doi.org/10.3390/min14111084
Liu C, Man Z, Li M. Study on the Dynamic Evolution of Mining-Induced Stress and Displacement in the Floor Coal-Rock Induced by Protective Layer Mining. Minerals. 2024; 14(11):1084. https://doi.org/10.3390/min14111084
Chicago/Turabian StyleLiu, Chun, Zhongyi Man, and Maolin Li. 2024. "Study on the Dynamic Evolution of Mining-Induced Stress and Displacement in the Floor Coal-Rock Induced by Protective Layer Mining" Minerals 14, no. 11: 1084. https://doi.org/10.3390/min14111084
APA StyleLiu, C., Man, Z., & Li, M. (2024). Study on the Dynamic Evolution of Mining-Induced Stress and Displacement in the Floor Coal-Rock Induced by Protective Layer Mining. Minerals, 14(11), 1084. https://doi.org/10.3390/min14111084