Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study
<p>The location map of the Dananhu No.1 Coal Mine.</p> "> Figure 2
<p>Roof, coal seam and floor strata structure peephole results for coal seam of panel 1306 return airway roadway.</p> "> Figure 3
<p>Mining roadway layout of panels 1304 and 1306.</p> "> Figure 4
<p>Statistical results of floor heave law and thickness of caving coal.</p> "> Figure 5
<p>Side surface-connected fissure of panel 1304. (<b>a</b>) Fissure size 0.32m, Small size of fissure; (<b>b</b>) Fissure size 0.51m, Large size of fissure; (<b>c</b>) Fissure size 0.53m, Fractured fissure.</p> "> Figure 6
<p>Stress environment of rock surrounding mining roadway with different caving coal thicknesses and roadway deformation profiles. (<b>a</b>) Small thickness of top coal (2 m); (<b>b</b>) Middle thickness of top coal (4 m); (<b>c</b>) Large thickness of top coal (6 m).</p> "> Figure 6 Cont.
<p>Stress environment of rock surrounding mining roadway with different caving coal thicknesses and roadway deformation profiles. (<b>a</b>) Small thickness of top coal (2 m); (<b>b</b>) Middle thickness of top coal (4 m); (<b>c</b>) Large thickness of top coal (6 m).</p> "> Figure 7
<p>Mechanical analysis of rotating rock block.</p> "> Figure 8
<p>Stress environment of surrounding rock around roadway with main roof fractured and roadway deformation profile.</p> "> Figure 9
<p>Numerical model with different top coal thicknesses. (<b>a</b>) Top 2 m of coal; (<b>b</b>) Top 4 m of coal; (<b>c</b>) Top 6 m of coal.</p> "> Figure 10
<p>Simulation results of roadway’s plastic zone distribution under different stress environments at top 2 m of coal (<span class="html-italic">β</span> = 30°). Note: <span class="html-italic">λ</span> is the principal stress ratio; <span class="html-italic">β</span> is the deflection direction of principal stress.</p> "> Figure 11
<p>Simulation results of roadway’s plastic zone distribution under different stress environments at top 4 m of coal (<span class="html-italic">β</span> = 45°). Note: <span class="html-italic">λ</span> is the principal stress ratio; <span class="html-italic">β</span> is the deflection direction of the principal stress.</p> "> Figure 12
<p>Comparison of field photos of coal pillar roadway, and numerical simulation results of surrounding rock deformation profile.</p> "> Figure 13
<p>Simulation results of roadway’s plastic zone distribution under different stress environments for top coal at 6 m (<span class="html-italic">β</span> = 10°). Note: <span class="html-italic">λ</span> is the principal stress ratio; <span class="html-italic">β</span> is the deflection direction of principal stress.</p> "> Figure 14
<p>Calculation model of plastic zone for rock surrounding non-equal pressure circular roadway.</p> "> Figure 15
<p>General shape of plastic zone in circular roadway obtained from theoretical calculation (<span class="html-italic">P</span><sub>3</sub> = 20 MPa, <span class="html-italic">a</span> = 2 m, <span class="html-italic">C</span> = 3 MPa, <span class="html-italic">φ</span> = 25°).</p> "> Figure 16
<p>Drawing system interface of plastic zone for rock surrounding roadway.</p> "> Figure 17
<p>Relationship between shape of butterfly-shaped plastic zone and direction of principal stress in rock surrounding roadway. Note: <span class="html-italic">α</span> is the angle between the maximum principal stress and the vertical direction; the clockwise direction is positive.</p> "> Figure 18
<p>Layout of test roadway and measuring station.</p> "> Figure 19
<p>Monitoring curve of floor heave deformation.</p> "> Figure 19 Cont.
<p>Monitoring curve of floor heave deformation.</p> "> Figure 20
<p>Curve of plastic zone range along with increase of support intensity.</p> "> Figure 21
<p>Length of hardened layer and floor digging within 8 h.</p> ">
Abstract
:1. Introduction
2. Deformation Characteristics and Stress Environment Analysis of Rock Surrounding Roadway
2.1. Structural Characteristics of Rock Surrounding Roadway
2.2. Monitoring of Law Governing Floor Heave in Mining Roadway
2.3. Analysis of Stress Environment of Surrounding Rock in Mining Roadway
3. Numerical Analysis of Roadway’s Floor Heave Mechanism
3.1. Modelling
3.2. Analysis of Numerical Simulation Results
3.3. Theoretical Analysis of Mining Roadway’s Floor Heave Mechanism
4. Control Measures for Roadway’s Floor Heave and Field Test
4.1. Adjusting Relationship Between Mining and Tunneling to Improve Stress Environment of Rock Surrounding Roadway
4.2. Optimization of Floor’s Hardening Thickness to Reduce Amount of Floor Digging
4.3. Determine Digging Floor Scheme According to Law of Asymmetric Floor Heave
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Simulation Scheme | Thickness of Roadway Caving Coal | Deflection Direction of Principal Stress (°) | Principal Stress Ratio | Principal Stress (MPa) | ||
---|---|---|---|---|---|---|
σ1 | σ2 | σ3 | ||||
Scheme 1 | 2 m | 30° | 1.5 | 9.75 | 7.50 | 6.50 |
2.0 | 13.00 | 9.00 | 6.50 | |||
2.5 | 16.25 | 10.00 | 6.50 | |||
Scheme 2 | 4 m | 45° | 2.0 | 13.00 | 9.00 | 6.50 |
2.5 | 16.25 | 10.00 | 6.50 | |||
3.0 | 19.50 | 12.00 | 6.50 | |||
60° | 2.0 | 13.00 | 9.00 | 6.50 | ||
2.5 | 16.25 | 10.00 | 6.50 | |||
3.0 | 19.50 | 12.00 | 6.50 | |||
Scheme 3 | 6 m | 10° | 1.0 | 6.50 | 6.50 | 6.50 |
1.5 | 9.75 | 7.50 | 6.50 | |||
2.0 | 13.00 | 9.00 | 6.50 |
Lithology | Bulk Density (Kg/m3) | K (GPa) | G (GPa) | C (MPa) | Φ (°) | |
---|---|---|---|---|---|---|
Carbonaceous mudstone | 2250 | 6.0 | 3.5 | 2.5 | 25 | 1.0 |
Mudstone | 2300 | 6.0 | 3.5 | 3.0 | 27 | 1.5 |
Sandy mudstone | 2420 | 8.0 | 5.0 | 5.0 | 29 | 2.5 |
3# coal seam | 1500 | 7.0 | 4.5 | 4.0 | 28 | 1.5 |
Siltstone | 2700 | 14.3 | 9.0 | 6.0 | 30 | 3.0 |
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Jia, H.; Wang, L.; Fan, K.; Peng, B.; Pan, K. Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study. Energies 2019, 12, 3009. https://doi.org/10.3390/en12153009
Jia H, Wang L, Fan K, Peng B, Pan K. Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study. Energies. 2019; 12(15):3009. https://doi.org/10.3390/en12153009
Chicago/Turabian StyleJia, Housheng, Luyao Wang, Kai Fan, Bo Peng, and Kun Pan. 2019. "Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study" Energies 12, no. 15: 3009. https://doi.org/10.3390/en12153009