Numerical and Experimental Study on a Novel Filling Support Method for Mining of Closely Spaced Multilayer Orebody
<p>Demonstration of the bolt-filling support system. (<b>a</b>) Schematic diagram of bolt-filling support; (<b>b</b>) Longitudinal section of drill hole arrangement for closely spaced multilayer orebodies; (<b>c</b>) Cross-sectional view of drill hole arrangement for closely spaced multilayer orebodies; (<b>d</b>) Longitudinal section of bolt-filling support system for closely spaced multilayer orebodies; (<b>e</b>) Top view of cable bolt network. 1—Surrounding rock, 2—Roof hole, 3—Goaf, 4—Floor hole, 5—Rock bolt, 6—Cable bolt, 7—Pre-loop, 8—Cable bolt network, 9—Backfill, 10—Ore body, 11—Ore pile.</p> "> Figure 1 Cont.
<p>Demonstration of the bolt-filling support system. (<b>a</b>) Schematic diagram of bolt-filling support; (<b>b</b>) Longitudinal section of drill hole arrangement for closely spaced multilayer orebodies; (<b>c</b>) Cross-sectional view of drill hole arrangement for closely spaced multilayer orebodies; (<b>d</b>) Longitudinal section of bolt-filling support system for closely spaced multilayer orebodies; (<b>e</b>) Top view of cable bolt network. 1—Surrounding rock, 2—Roof hole, 3—Goaf, 4—Floor hole, 5—Rock bolt, 6—Cable bolt, 7—Pre-loop, 8—Cable bolt network, 9—Backfill, 10—Ore body, 11—Ore pile.</p> "> Figure 2
<p>Correlation between Poisson’s ratio and stiffness ratio and friction coefficient. (<b>a</b>) Relationship between stiffness ratio <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="normal">k</mi> <mi mathvariant="normal">n</mi> </msub> <mo>/</mo> <msub> <mi mathvariant="normal">k</mi> <mi mathvariant="normal">s</mi> </msub> </mrow> </semantics></math> and Poisson’s ratio <math display="inline"><semantics> <mi mathvariant="sans-serif">ν</mi> </semantics></math>; (<b>b</b>) Relationship between friction coefficient μ and Poisson’s ratio <math display="inline"><semantics> <mi mathvariant="sans-serif">ν</mi> </semantics></math>.</p> "> Figure 3
<p>Correlation between elastic modulus and effective modulus of contact, friction coefficient, and stiffness ratio. (<b>a</b>) Relationship between effective modulus of contact <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="normal">E</mi> <mi mathvariant="normal">c</mi> </msub> </mrow> </semantics></math> elastic modulus <math display="inline"><semantics> <mi mathvariant="normal">E</mi> </semantics></math>; (<b>b</b>) Relationship between square of friction coefficient <math display="inline"><semantics> <mrow> <msup> <mi mathvariant="sans-serif">μ</mi> <mn>2</mn> </msup> </mrow> </semantics></math> and elastic modulus <math display="inline"><semantics> <mi mathvariant="normal">E</mi> </semantics></math>; (<b>c</b>) Relationship between logarithm of stiffness ratio <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi>ln</mi> <mo>(</mo> <mi mathvariant="normal">k</mi> </mrow> </mrow> <mi mathvariant="normal">n</mi> </msub> <mo>/</mo> <msub> <mi mathvariant="normal">k</mi> <mi mathvariant="normal">s</mi> </msub> <mo>)</mo> </mrow> </semantics></math> and elastic modulus <math display="inline"><semantics> <mi mathvariant="normal">E</mi> </semantics></math>.</p> "> Figure 4
<p>Correlation between uniaxial compressive strength and the tensile strength, cohesion of bonds, and friction coefficient. (<b>a</b>) Relationship between tensile strength <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">σ</mi> </mrow> </mrow> <mi mathvariant="normal">n</mi> </msub> </mrow> </semantics></math> and uniaxial compressive strength <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">c</mi> </msub> </mrow> </semantics></math>; (<b>b</b>) Relationship between cohesion of bonds c and uniaxial compressive strength <math display="inline"><semantics> <mrow> <mo> </mo> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">c</mi> </msub> </mrow> </semantics></math>; (<b>c</b>) Relationship between friction coefficient μ and uniaxial compressive strength <math display="inline"><semantics> <mrow> <mo> </mo> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">c</mi> </msub> </mrow> </semantics></math>.</p> "> Figure 5
<p>Variation curve of rock’s tensile strength with cohesion and tensile strength of bonds. (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">t</mi> </msub> </mrow> </semantics></math> − c; (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">t</mi> </msub> </mrow> </semantics></math> − <math display="inline"><semantics> <mrow> <msub> <mi mathvariant="sans-serif">σ</mi> <mi mathvariant="normal">n</mi> </msub> </mrow> </semantics></math>.</p> "> Figure 6
<p>Uniaxial compressive experiment of surrounding rock and ore. (<b>a</b>) Uniaxial compression experiment of carbonaceous shale; (<b>b</b>) Uniaxial compression experiment of Vanadium-bearing shale.</p> "> Figure 7
<p>Stress–strain curve of surrounding rock and ore (1—Simulation curve, 2—Test curve). (<b>a</b>) Surrounding rock; (<b>b</b>) ore.</p> "> Figure 8
<p>PFC2D numerical simulation model of double-layer ore.</p> "> Figure 9
<p>Mechanics simulation of surrounding rock without support. (<b>a</b>) No support in the upper goaf; (<b>b</b>) Distribution of fractures when the upper goaf is not supported; (<b>c</b>) Distribution of the force chains when the upper goaf is not supported.</p> "> Figure 10
<p>Mechanics simulation of surrounding rock with the upper goaf 100% filled. (<b>a</b>) Filling support in the upper goaf (100%); (<b>b</b>) Distribution of fractures when the upper goaf is 100% filled; (<b>c</b>) Distribution of the force chains when the upper goaf is 100% filled.</p> "> Figure 11
<p>Mechanics simulation of surrounding rock with the upper goaf 95% filled. (<b>a</b>) Filling support in the upper goaf (95%); (<b>b</b>) Distribution of fractures when the upper goaf is 95% filled; (<b>c</b>) Distribution of the force chains when the upper goaf is 95% filled.</p> "> Figure 12
<p>Mechanics simulation of surrounding rock with bolt-fill support. (<b>a</b>) Bolt-filling support in the upper goaf; (<b>b</b>) Distribution of fractures with upper bolt-filling support; (<b>c</b>) Distribution of the force chains with upper bolt-filling support.</p> "> Figure 13
<p>River sand screening.</p> "> Figure 14
<p>Specimen of similar material model.</p> "> Figure 15
<p>Similarity model plan.</p> "> Figure 16
<p>Model building process. (<b>a</b>) Paste the model background image; (<b>b</b>) Mixing materials; (<b>c</b>) Filling materials in layer; (<b>d</b>) Finished model.</p> "> Figure 17
<p>Pre-experimental system test.</p> "> Figure 18
<p>Sensor Installation. (<b>a</b>) Fixing strain gages; (<b>b</b>) Connecting strain gages to monitoring system.</p> "> Figure 18 Cont.
<p>Sensor Installation. (<b>a</b>) Fixing strain gages; (<b>b</b>) Connecting strain gages to monitoring system.</p> "> Figure 19
<p>Layout of the stopes and monitoring points for the double-layer ore body mining experiment.</p> "> Figure 20
<p>Excavation process of experiment 1. (<b>a</b>) Excavation of E1; (<b>b</b>) Excavation of E2; (<b>c</b>) Excavation of F1; (<b>d</b>) Excavation of F2.</p> "> Figure 21
<p>Stope and monitoring point arrangement.</p> "> Figure 22
<p>Mining process of experiment 2. (<b>a</b>) Excavation of A1, A2, A3; (<b>b</b>) Excavation of B1, B2, B3 and support of A1, A2.</p> "> Figure 23
<p>Picture of bolt-filling support. (<b>a</b>) Similar experimental bolt-filling support diagram; (<b>b</b>) Rock bolt and cable bolt connection diagram.</p> "> Figure 24
<p>Strain-time curve of E1 stope roof.</p> "> Figure 25
<p>Strain-time curve of F1 stope roof (interlayer).</p> "> Figure 26
<p>Strain–time curve of the pillars.</p> "> Figure 27
<p>Strain–time curve of the roofs in experiment 2.</p> ">
Abstract
:1. Introduction
2. Bolt-Filling Support Method and System
3. Numerical Simulation Study of Bolt-Filling Support
3.1. Calibration of the Microscopic Parameters
3.2. Fracture Expansion of Surrounding Rock and Distribution Law of Force Chain
3.2.1. Upper Goaf Not Supported
3.2.2. Upper Goaf 100% Filled
3.2.3. Upper Goaf 95% Filled
3.2.4. Bolt-Filling Support
4. Similarity Simulation Experiment of Bolt-Filling Support
4.1. Similarity Experiment Design
4.1.1. Similarity Constants
- (1)
- Geometric Similarity Constant
- (2)
- Bulk Density Similarity Constant
- (3)
- Strength Similarity Constant
- (4)
- Time Similarity Constant
4.1.2. Selection and Preparation of Similarity Experiment Materials
4.1.3. Similarity Model Building
4.2. The Similarity Simulation Experiment Process
4.2.1. Arrangement of Strain Gages
4.2.2. Similarity Experiment 1: Excavation of Double-Layer Ore Body without Support
4.2.3. Similarity Experiment 2: Excavation of Double-Layer Ore Body with Support
4.3. Experiment Results
4.3.1. Results of Experiment 1
4.3.2. Results of Experiment 2
5. Discussion
6. Conclusions
- (1)
- A novel bolt-filling support method is proposed in this research.
- (2)
- It is revealed that, by numerical simulation of fracture distribution and force chains, bolt-filling support not only reduces the roof load of the lower goaf, but also helps to relieve the tensile stress concentration in the roof of the upper goaf caused by incomplete filling, which is effective for the support of closely spaced multilayer goaf.
- (3)
- It is found that, by similarity experiments, the deformation of the roof and interlayer under bolt-filling support is the smallest, which has a high consistency with the numerical simulation results.
- (4)
- Therefore, it is safe to say that the bolt-filling support performs better than other conventional support methods for mining closely spaced multilayer orebodies, so that to promote mining safety and the stability of the roof and interlayer.
7. Patents
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Rocks | E (GPa) | |||
---|---|---|---|---|
Ore | 1.09 | 0.22 | 1.33 | 0.23 |
Surrounding Rock | 1.48 | 0.20 | 2.35 | 0.30 |
Rocks | C (Mpa) | Ec (Gpa) | |||
---|---|---|---|---|---|
Ore | 0.37 | 0.75 | 0.56 | 0.70 | 1.84 |
Surrounding Rock | 0.56 | 1.13 | 0.75 | 0.30 | 1.39 |
Support Method | Number of Fractures | Fractures on the Roof of Upper Goaf | Tensile Force Chains on the Roof of Upper Goaf | Fractures on the Roof of Lower Goaf | Tensile Force Chains on the Roof of Lower Goaf |
---|---|---|---|---|---|
Unsupported | 1311 | Extremely developed | Dense | Extremely developed | not so dense |
Complete filling (100%) | 379 | Not developed | Sparse | Developed | dense |
Incomplete filling (95%) | 652 | Slightly developed | Not sparse | Developed | dense |
Bolt-filling support | 410 | Not developed | Sparse | Not developed | sparse |
Rock Layer | Density/(kg/m3) | Compressive Strength/MPa | Modulus of Elasticity/GPa | Poisson’s Ratio | Proportion Number |
---|---|---|---|---|---|
Vanadium-bearing shale | 1661.74 | 0.51 | 0.39 | 0.21 | 964 |
Carbonaceous shale | 1620.98 | 0.33 | 0.34 | 0.20 | 1037 |
Siliceous shale | 1704.41 | 0.75 | 0.40 | 0.21 | 837 |
Backfill | 1232.39 | 0.02 | —— | —— | 1019 |
Rock Layer | Volume/m3 | Total amount/kg | Cement/kg | Gypsum/kg | River Sand/kg |
---|---|---|---|---|---|
Vanadium-bearing shale | 0.119 | 198.19 | 11.30 | 7.53 | 169.45 |
Carbonaceous shale | 0.588 | 953.10 | 24.69 | 57.62 | 823.13 |
Siliceous shale | 1.237 | 2107.93 | 66.75 | 155.75 | 1780.03 |
Backfill | 0.011 | 13.61 | 0.12 | 1.06 | 11.76 |
Total | 1.955 | 3272.83 | 102.86 | 221.96 | 2784.37 |
Preparation quantity | 2.350 | 3927.40 | 123.43 | 266.35 | 3341.24 |
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Chi, X.; Zhang, Z.; Li, L.; Wang, Q.; Wang, Z.; Dong, H.; Xie, Y. Numerical and Experimental Study on a Novel Filling Support Method for Mining of Closely Spaced Multilayer Orebody. Minerals 2022, 12, 1523. https://doi.org/10.3390/min12121523
Chi X, Zhang Z, Li L, Wang Q, Wang Z, Dong H, Xie Y. Numerical and Experimental Study on a Novel Filling Support Method for Mining of Closely Spaced Multilayer Orebody. Minerals. 2022; 12(12):1523. https://doi.org/10.3390/min12121523
Chicago/Turabian StyleChi, Xiuwen, Zhuojun Zhang, Lifeng Li, Qizhou Wang, Zongying Wang, Haoran Dong, and Yu Xie. 2022. "Numerical and Experimental Study on a Novel Filling Support Method for Mining of Closely Spaced Multilayer Orebody" Minerals 12, no. 12: 1523. https://doi.org/10.3390/min12121523