scholarly journals A Case Study of Effective Support Working Resistance and Roof Support Technology in Thick Seam Fully-Mechanized Face Mining with Hard Roof Conditions

2017 ◽  
Vol 9 (6) ◽  
pp. 935 ◽  
Author(s):  
Wei-bin Guo ◽  
Hong-sheng Wang ◽  
Guo-wei Dong ◽  
Lei Li ◽  
Yao-guang Huang
Keyword(s):  
Thick Seam ◽  
Hard Roof ◽  
Working Resistance ◽  
Roof Support

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Safe and Efficient Coal Mining Below the Goaf: A Case Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 864 ◽  
Author(s):  
Weidong Pan ◽  
Shaopeng Zhang ◽  
Yi Liu
Keyword(s):  
Abutment Pressure ◽  
Theoretical Calculations ◽  
Distribution Law ◽  
Working Face ◽  
Strata Behavior ◽  
Working Resistance ◽  
Behavior Characteristics ◽  
Theoretical Analyses ◽  
Important Significance

Mining at the fully mechanized working face below the goaf of the short-distance coal seam is influenced by the upper goaf. To address this problem, methods such as theoretical analyses, numerical simulation, and on-site measurement are used to study the strata behavior characteristics of the Ningxia Lingxin Coal Mine 051508 working face in this study. The roof weighting intervals of the working faces below the goaf and the non-goaf are obtained via theoretical calculations. The stoping processes of the working faces below the goaf and the non-goaf are simulated with FLAC3D to obtain the distribution law of the bearing pressure and plastic zones before the working face. Based on the statistical analysis of the measured working resistance of the supports and its distribution, the roof weighting interval of the working face mining below the goaf is obtained. The results show that the roof weighting interval and the advanced abutment pressure during mining at the working face below the goaf are smaller than those below the non-goaf, providing a reasonable theoretical basis for mining below the goaf, and having important significance for safe and efficient mining.

scholarly journals Case study on the mining‐induced stress evolution of an extra‐thick coal seam under hard roof conditions

2020 ◽  
Vol 8 (9) ◽  
pp. 3174-3185 ◽  
Author(s):  
Cong Li ◽  
Heping Xie ◽  
Mingzhong Gao ◽  
Jing Xie ◽  
Guangdi Deng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Stress Evolution ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Induced Stress

scholarly journals Case Analysis of Damages to Control Hydraulics of the Leg in the Powered Roof Support Section

2019 ◽  
Vol 105 ◽  
pp. 03013
Author(s):  
Janina Świątek ◽  
Kazimierz Stoiński
Keyword(s):  
Coal Mining ◽  
Case Analysis ◽  
Hard Coal ◽  
Support Section ◽  
Full Extension ◽  
Safety Measures ◽  
Bench Tests ◽  
Hard Coal Mining ◽  
Roof Support

The article discusses a case of security hazard in a longwall equipped with a properly selected chock shield support with two legs, technically efficient, introduced to the market and for operation in compliance with the requirements covering Polish hard coal mining. As a cause of the hazard an accidental coincidence was indicated, such as the occurrence of a tremor at an area with unfavourable geometry for the operation of the support section and leg (including the shift of the double-telescopic leg from the 1st to the 2nd hydraulic stage) at the time of the mining process. Immediate safety measures were applied successfully. They were aimed at minimizing the conditions dangerous to the crew. The section was withdrawn and spragged again. As a result, the leg operated in full extension mode of the 1st hydraulic stage, obtaining the required strength and geometry of the section and leg. The presented case study will be additionally supplemented in the future with selected analytical and bench tests.

Influence of hard-roof on gas accumulation in overlying strata: A case study

2021 ◽  
Vol 90 ◽  
pp. 103948
Author(s):  
Yang Zhao ◽  
Baiquan Lin ◽  
Ting Liu ◽  
Wei Yang
Keyword(s):  
Gas Accumulation ◽  
Hard Roof ◽  
Overlying Strata

Effect of Premining on Hard Roof Distress Behavior: A Case Study

2019 ◽  
Vol 52 (6) ◽  
pp. 1871-1885 ◽  
Author(s):  
Weidong Pan ◽  
Xiaodong Nie ◽  
Xinyuan Li
Keyword(s):  
Hard Roof
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