Case study on pressure-relief mining technology without advance tunneling and coal pillars in longwall mining

The rockburst hazard has always been an important issue affecting the safety production of coal mines in China. The unreasonable sequencing of roadway driving can lead to the dynamic instability of coal pillars, which subsequently causes rockburst accidents in roadway backfilling mining engineering and poses a serious threat to the safety of the mines. Roadway backfilling mining technology is an effective approach with which to mine corner residual coal resources under buildings, railways, and rivers. An energy density criterion is established and programmed with FISH language using numerical analysis software for the rockburst risk evaluation of coal pillars. On this basis, a numerical simulation model is established based on four scheme types, namely, the sequential mining, one-roadway interval mining, two-roadway interval mining, and three-roadway interval mining schemes. The influence of the backfilling roadway driving sequence on coal pillar stability is investigated, and the change law of vertical stress and energy density factor of coal pillars in different driving sequences in roadway backfilling mining technology are analyzed. According to the research results, the maximum energy density factor value of 21,172 J/m4 for coal pillars in one-roadway interval mining is the lowest among the different schemes. Therefore, the one-roadway interval mining scheme is the optimal choice in roadway backfilling mining technology. The results can be treated as an important basis for the prevention and treatment of coal pillar instability and rockburst in roadway backfilling mining technology.

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Forecast of methane emission from closed underground coal mines exploited by longwall mining – A case study of Anna coal mine

Journal of Sustainable Mining ◽

10.1016/j.jsm.2018.06.004 ◽

2018 ◽

Vol 17 (4) ◽

pp. 184-194 ◽

Cited By ~ 10

Author(s):

Adam Duda ◽

Alicja Krzemień

Keyword(s):

Coal Mine ◽

Methane Emission ◽

Longwall Mining ◽

Coal Mines ◽

Underground Coal Mines

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Automatic Roadway Backfilling of Caving Gangue for Cutting Roofs by Combined Support on Gob-Side Entry Retaining with No-Pillars: A Case Study

Advances in Materials Science and Engineering ◽

10.1155/2019/8736103 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Shengrong Xie ◽

Xiaoyu Wu ◽

Dongdong Chen ◽

Yaohui Sun ◽

Junchao Zeng ◽

...

Keyword(s):

Longwall Mining ◽

Control Process ◽

Coal Pillar ◽

Main Roof ◽

Control Effect ◽

Mining Technology ◽

Thick Coal Seam ◽

Immediate Roof ◽

Seam Mining ◽

And Control

Automatic roadways on gob-side entry retaining with no-pillars are used for longwall mining technology. The mining technology with no-pillars can recover coal pillar resources and reduce the amount and cost of roadway excavations. Automatic roadway technology for cutting roofs by combined support on gob-side entry retaining with no-pillars is adopted for the condition of thick immediate roof and medium-thick coal seam mining, cutting off the immediate roof and the main roof on the gob by combined support. The fractured roof forms gangue blocks to fill the gob and loads the overlying strata. The gangue control system is placed on the roadside, which controls the caving gangue to form a gangue rib. In this paper, the viewpoints and key technologies (the roof-cutting technology, the reinforcement and support technology, the gangue rib control technology, and the auxiliary support technology) of automatic roadway technology for cutting roofs by combined support on the gob-side entry retaining with no-pillars are introduced. Furthermore, the formation and control process are explained. The numerical simulation is used to simulate and analyze the roof hanging and the roof cutting structures. In addition, a field engineering test is performed. The field test shows that automatic roadway technology for cutting roofs by combined support on gob-side entry retaining with no-pillars is feasible. This process uses construction techniques and technologies to meet on-site production needs. The combined support has high resistance strength and is shrinkable. In engineering applications, the combined support has a low damage rate. The deformation of the automatic roadway with gob-side entry retaining is small, and the control effect is significant.

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Zoning Control Technology of Gob-Side Roadway Driving with Small Coal Pillar Facing Mining in a Special Isolated Island Working Face: A Case Study

Applied Sciences ◽

10.3390/app112210744 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10744

Author(s):

Changliang Han ◽

Houqiang Yang ◽

Nong Zhang ◽

Rijian Deng ◽

Yuxin Guo

Keyword(s):

Control Method ◽

Coal Pillar ◽

Control Technology ◽

Stability Zone ◽

Pressure Relief ◽

Collaborative Control ◽

Working Face ◽

Underground Coal Mines ◽

Engineering Practices

The gob-side roadway in an isolated island working face is a typical representative of a strong mining roadway, which seriously restricts the efficient and safe production of underground coal mines. With the engineering background of the main transportation roadway 1513 (MTR 1513) of the Xinyi Coal Mine, this paper introduces the engineering case of gob-side roadway driving with small coal-pillar facing mining in an isolated island working face under the alternate mining of wide and narrow working faces. Through comprehensive research methods, we studied zoning disturbance deformation characteristics and stress evolution law of gob-side roadway driving under face mining. Based on the characteristics of zoning disturbance, MTR 1513 is divided into three zones, which are the heading face mining zone, the mining influenced zone, and the mining stability zone. A collaborative control technology using pressure relief and anchoring is proposed, and the differentiated control method is formed for the three zones. For the heading face mining zone, the control method of anchoring first and then pressure relief is adopted; for the mining influenced zone, the control idea of synchronous coordination of pressure relief and anchorage is adopted; for the mining stability zone, the control method of anchoring without pressure relief is adopted. Engineering practices show that the disturbance influence distance of working face 1511 on MTR 1513 changes from 110 m advanced to 175 m delay. At this time, the surrounding rock deformation is effectively controlled, which verified the rationality of the division and the feasibility of three zoning control technology. The research results can provide reference for gob-side roadway driving with small coal pillar facing mining in a special isolated island working face.

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Numerical investigation into impacts of major fault on coal burst in longwall mining – A case study

International Journal of Rock Mechanics and Mining Sciences ◽

10.1016/j.ijrmms.2021.104907 ◽

2021 ◽

Vol 147 ◽

pp. 104907

Author(s):

Chunchen Wei ◽

Chengguo Zhang ◽

Ismet Canbulat ◽

Wanpeng Huang

Keyword(s):

Numerical Investigation ◽

Longwall Mining ◽

Major Fault

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Mechanisms behind strong strata behaviour in high longwall mining face-ends under shallow covers

Journal of Geophysics and Engineering ◽

10.1093/jge/gxz027 ◽

2019 ◽

Vol 16 (3) ◽

pp. 559-570 ◽

Cited By ~ 4

Author(s):

Weibing Zhu ◽

Xiangrui Qi ◽

Jinfeng Ju ◽

Jingmin Xu

Keyword(s):

Longwall Mining ◽

Coal Pillar ◽

Field Measurements ◽

Main Roof ◽

Longwall Face ◽

Effective Control ◽

Coal Seams ◽

Roof Collapse ◽

Coal Pillars ◽

Roadway Deformation

Abstract Safe and efficient mining of shallow coal seams relies on the understanding and effective control of strata behaviour. Field measurements, theoretical analysis and numerical simulations are presented in this study to investigate the mechanism behind abnormal strata behaviour, such as roof collapse and severe roadway deformation, that occurs in high longwall face-ends under shallow cover. We observed that coal pillars with two sides being mined out become unstable when the cover depth exceeds a certain value. The instability of the coal pillar can alter the fracture line of the overlying strata, triggering a reversed rotation of the ‘curved triangle blocks’ that form after the breakage of the overlying main roof. The revolving blocks apply stress on the roof strata directly above the longwall face-end, resulting in roof collapse. The collapse of both the coal pillars and the roof also leads to the advancement and increase of the overlying abutment pressure, which further causes severe roadway deformation in front of the working face. The strong strata behaviour that occurs in high longwall face-ends with shallow cover is presented in this study and countermeasures are proposed, such as widening or strengthening the coal pillar, or implementing destress blasting. The countermeasures we proposed and the results of our analyses may facilitate the safe mining of shallow coal seams with similar problems in the future, and may improve the safety and efficient working of coal mines.

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In situ investigations into mining-induced hard main roof fracture in longwall mining: A case study

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2019.104188 ◽

2019 ◽

Vol 106 ◽

pp. 104188 ◽

Cited By ~ 4

Author(s):

Shang Yang ◽

Jun Wang ◽

Xuehui Li ◽

Jianguo Ning ◽

Pengqi Qiu

Keyword(s):

Longwall Mining ◽

Main Roof

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