Optimization and Practice of Support Working Resistance in Fully-Mechanized Top Coal Caving in Shallow Thick Seam
Abstract
:1. Introduction
2. Engineering Background
2.1. General Situation of 1311 Caving Working Face
2.2. General Situation of 1311 Caving Working Face
2.3. Mine Pressure Behavior of 1311 Caving Working Face
3. An Inversion Optimizing Method
3.1. Four Support Working Resistance
- (1)
- Rated working resistance pThe rated working resistance is the maximum force that the hydraulic support exerts onto the roof.
- (2)
- Average working resistanceAverage working resistance is the average of the end working resistance during the roof weighting stage.
- (3)
- Average-partial working resistanceAverage-partial working resistance was defined as the sum of average working resistance and the mean square error.
- (4)
- Average-upper working resistance p2The average-upper working resistance is defined as the sum of average working resistance and the double mean square error.
3.2. The Partition of Roof Control Effect Level
3.3. Working Resistance Design Flow
3.4. Reasonable Working Resistance Calculation
4. Top Coal Cavability and Roof Subsidence under Different Supporting Strengths
4.1. Top Coal Cavability under Different Supporting Strength
4.2. Roof Subsidence under Different Supporting Strength
5. Engineering Practice
5.1. General Situation of 1322 Caving Working Face
5.2. Mine Pressure Behavior of 1322 Caving Working Face
6. Conclusions
- (1)
- An inversion optimizing method and design flow of working resistance in fully-mechanized top coal caving in shallow thick seam was put forward by considering two very important reference indexes-roof control effect and working resistance overrun percentage. This method and design flow were applied to calculate the working resistance of 1313 working face and 1322 working face and were determined to be with 8786 kN and 10,000 kN. The applied working resistance (8000 kN) is lower than the calculated working resistance (8000 kN) in the 1313 working face which resulted in pillar shrinkage. Therefore, for the 1322 working face, 10,000 kN was determined as the required working resistance.
- (2)
- The simulation model of fully-mechanized top coal caving working face is built by using the UDEC software to justify the method of calculating working resistance with analyzing the top coal cavability and roof subsidence. The roof subsidence under supporting strength of 1.2 MPa (10,000 kN) is 120 mm, which falls within the ‘Good’ range of roof control effect partial. The plastic zone of top coal developed well under supporting strength of 1.2 MPa (10,000 kN), which benefits top coal caving.
- (3)
- The top-cave hydraulic support (ZF10000/23/35) is selected to employ in 1322 plane. The working resistance was monitored during the working face advanced distance is from 445 m to 619 m. The working resistance is 80–90% of working rated resistance. The practice shows that the support worked well and no support pillar shrinkage and crushing happened, which justify the method of calculating working resistance with field feedback.
- (4)
- There are a large number of shallow coal mines where top coal caving method has been applied in the western region of China. Large mining height, special overburden structure, and shallow depth coal seam, many problems were induced in top coal mining working face, such as roof shear, support crushing, and threatened safety of the working face. The research achievements of this paper provide a new support working resistance design flow to guarantee safety mining in those coal mines working face.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Serial No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
---|---|---|---|---|---|---|---|
Roof subsidence (mm) | ≤90 | 91–110 | 111–270 | 271–330 | 331–475 | 476–525 | ≥526 |
Control effect partial | Excellent | Better | Good | Normal | Ordinary | Bad | Poor |
Serial No. | Four Working Resistance | Value (kN) | Roof Subsidence/mm | Control Effect Partial | Supporting Strength (MPa) | Proportion Type | Overrun Percentage/% | Avg. (%) | |||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
No. 25 | No. 50 | No. 60 | No. 70 | No. 90 | No. 110 | - | |||||||
1 | 8000 | 329 | Normal | 1.00 | A1 | 16.2 | 32.5 | 60.8 | 55.2 | 0.0 | 3.2 | 28.0 | |
A2 | 5.7 | 17.7 | 39.1 | 26.4 | 0.0 | 0.8 | 16.9 | ||||||
2 | 7240 | 462 | Ordinary | 0.90 | A1 | 32.8 | 76.8 | 82.9 | 85.1 | 67.3 | 17.4 | 60.4 | |
A2 | 11.5 | 41.8 | 53.3 | 40.7 | 38.5 | 6.4 | 31.7 | ||||||
3 | 7912 | 351 | Ordinary | 0.99 | A1 | 18.8 | 37.4 | 65.8 | 55.2 | 0.0 | 6.4 | 30.3 | |
A2 | 6.6 | 20.3 | 42.3 | 26.4 | 0.0 | 1.1 | 16.1 | ||||||
4 | 8786 | 267 | Good | 1.10 | A1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
A2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||||||
5 | Cycle No./n | N = 182 | - | - | - | - | 64 | 99 | 117 | 87 | 104 | 46 | 86 |
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Huang, P.; Ju, F.; Jessu, K.V.; Xiao, M.; Guo, S. Optimization and Practice of Support Working Resistance in Fully-Mechanized Top Coal Caving in Shallow Thick Seam. Energies 2017, 10, 1406. https://doi.org/10.3390/en10091406
Huang P, Ju F, Jessu KV, Xiao M, Guo S. Optimization and Practice of Support Working Resistance in Fully-Mechanized Top Coal Caving in Shallow Thick Seam. Energies. 2017; 10(9):1406. https://doi.org/10.3390/en10091406
Chicago/Turabian StyleHuang, Peng, Feng Ju, Kashi Vishwanath Jessu, Meng Xiao, and Shuai Guo. 2017. "Optimization and Practice of Support Working Resistance in Fully-Mechanized Top Coal Caving in Shallow Thick Seam" Energies 10, no. 9: 1406. https://doi.org/10.3390/en10091406