Preliminary Design and On-Site Testing Methodology of Roof-Cutting for Entry Retaining in Underground Coal Mine
Abstract
:1. Introduction
2. Materials and Methods
2.1. Engineering Background
2.2. Roof Detection
2.3. Roof-Cutting Design
2.3.1. Cutting Height
2.3.2. Roof-Cutting Angle
2.4. Blasting Design
2.4.1. Preliminary Design of Charge Structure
2.4.2. Interval of Blast Holes
2.4.3. Initiation Quantity
2.5. On-Site Blasting Tests
3. Results
3.1. Stemming Medium
3.2. Blasting Parameters
3.3. Fissure Formation
3.4. Post-Mining Monitoring
4. Discussion
4.1. Comparison with Similar Studies
4.2. Limitations and Further Research Directions
5. Conclusions
- (1)
- The preliminary design of the blasting parameters can be achieved based on theories and on-site geological conditions. The roof lithology can be determined using a mine-drilling imaging trajectory detection device. The cutting height and angle can be determined using Equations (1)–(6).
- (2)
- Since on-site test methods are provided, the fissure formation mainly depends on the stemming materials, charge structure, and blasting pattern. The effect of different blasting designs can be obtained via fissure formation rate analysis.
- (3)
- The effect of pre-split blasting can be determined and adjusted based on post-mining monitoring data. The loading state of the hydraulic shield in the working face can be used to analyze the effectiveness of roof caving in the goaf.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Thickness (minimum~maximum/average) (m) | 1.00~2.76/1.88 |
Inclined angle (minimum~maximum/average) (°) | 16~23/20 |
Gas (m3/min) | 0.27~0.34 |
CO2 (m3/min) | 1.29~2.12 |
Explosive index (%) | 41.50 |
Spontaneous combustion | Yes |
Layer | Lithology | Thickness (m) | Features |
---|---|---|---|
Main roof | Dark gray siltstone | 5.24 | Dark gray with uneven fractures, containing a large number of plant fossils such as Koda trees, with siderite nodules and a slightly thin strip-like layer at the bottom. |
Immediate roof | Dark gray siltstone | 1.75 | Dark gray and densely organized, containing siderite nodules and plant fossils, with dark streaks of grayish brown at the top, light streaks at the bottom, and grayish-white streaks containing plant carbonization. |
Immediate floor | Dark gray claystone | 2.07 | Contains plant root fossils, sometimes with thin coal lines, and local siltstone with high carbon content, a 0.25 m thick coal line in the lower part in powder form, with good coal quality. |
Floor | Dark gray siltstone | 3.39 | Stratification is developed, containing plant fossils such as Koda trees, with locally occurring siderite nodules and sometimes thin coal seams. |
Hole | Charge Structure | Stemming (m) | Stemming Material | Observation | |
---|---|---|---|---|---|
1 | 147 | 431 | 2.5 m | 1 | Stemming collapse |
149 | 422 | 2.5 m | 1 | Stemming collapse | |
151 | 332 | 2.5 m | 1 | Stemming collapse | |
2 | 159 | 431 | 2.5 m | 2 | Stemming collapse |
160 | 0 | Smoke | |||
161 | 431 | 2.5 m | 2 | Stemming collapse | |
163 | 431 | 3 m | 2 | Stemming collapse | |
165 | 421 | 2.5 m | 2 | Stemming collapse | |
3 | 243 | 431 | 2.5 m | 3 | Stemming collapse |
244 | 431 | 2.5 m | 3 | Stemming collapse | |
250 | 431 | 2.5 m | 3 | ||
251 | 0 | Smoke | |||
252 | 431 | 2.5 m | 3 | ||
4 | 241 | 3221 | 2.5 m | 4 | |
240 | 3221 | 2.5 m | 4 | ||
236 | 431 | 2.5 m | 4 | ||
235 | 431 | 2.5 m | 4 | Collapse | |
5 | 72 | 441 | 2.5 m | 4 | |
62 | 441 | 2.5 m | 4 | ||
52 | 441 | 2.5 m | 4 | Collapse |
Shield | Initial Abutment Pressure | Periodic Abutment Pressure | ||
---|---|---|---|---|
Magnitude/MPa | Distance/m | Magnitude/MPa | Distance/m | |
130# | 29.5 | 29.0 | 28.5 | 17.6 |
13# | 38.7 | 41.0 | 37.8 | 14.8 |
4# | 27.4 | 49.4 | 26.5 | 21.2 |
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Chen, Y.; Zhang, Z.; Bao, S.; Yang, H.; Shi, M.; Cao, C. Preliminary Design and On-Site Testing Methodology of Roof-Cutting for Entry Retaining in Underground Coal Mine. Sensors 2023, 23, 6391. https://doi.org/10.3390/s23146391
Chen Y, Zhang Z, Bao S, Yang H, Shi M, Cao C. Preliminary Design and On-Site Testing Methodology of Roof-Cutting for Entry Retaining in Underground Coal Mine. Sensors. 2023; 23(14):6391. https://doi.org/10.3390/s23146391
Chicago/Turabian StyleChen, Ying, Zikai Zhang, Shiji Bao, Hongtao Yang, Mingzhe Shi, and Chen Cao. 2023. "Preliminary Design and On-Site Testing Methodology of Roof-Cutting for Entry Retaining in Underground Coal Mine" Sensors 23, no. 14: 6391. https://doi.org/10.3390/s23146391
APA StyleChen, Y., Zhang, Z., Bao, S., Yang, H., Shi, M., & Cao, C. (2023). Preliminary Design and On-Site Testing Methodology of Roof-Cutting for Entry Retaining in Underground Coal Mine. Sensors, 23(14), 6391. https://doi.org/10.3390/s23146391