The failure law and support technique for fully-mechanized top-coal caving working face in extra-thick coal seams in deep coal mines

2014 ◽  
pp. 775-780
Keyword(s):  
Coal Mines ◽  
Coal Seams ◽  
Working Face

scholarly journals THEORY AND PRACTICE OF DETERMINING THE CATEGORY HAZARD OF COAL MINES BY THE GAS FACTOR

2021 ◽  
Author(s):  
Elvira Filatieva ◽  
◽  
Aleksandr Oleinichenko ◽  
Mykhailo Filatiev ◽  
Valerii Sokolenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Coal Mines ◽  
Field Studies ◽  
Theory And Practice ◽  
Gas Release ◽  
Coal Seams ◽  
Working Face ◽  
Gas Bearing ◽  
Enclosing Rocks ◽  
Safe Mining

A comparative analysis of the theoretical and practical definition of the category hazard of coal mines by gas factor based on experimental data obtained in real conditions of mining gas-bearing coal seams is presented. The mine's hazard category by gas factor is determined in accordance with the current regulatory document. The processing of experimental data obtained in field studies leads to contradictions in the requirements for the safe mining of gas-bearing coal seams. The necessity of changing the regulatory framework for predicting methane release and establishing the category hazard of mines by gas factor is substantiated, as well as the theoretical part of the research is experimentally confirmed and practical proposals are given to improve the requirements of regulatory documents for the safe mining of gas-bearing coal seams. The gas release from seven possible sources, the exposed surface of the working face, the undermined adjacent seams and their enclosing rocks, the overworked adjacent seams and enclosing rocks, the worked-out space of the stopped lavas, are accepted for consideration. The studies have shown that by removal the bottom from cut and the area of the mined-out space of the operated section and the wing of the mine field, taking into account the stopped longwalls, it is possible to predict the processes of rock displacement that determine the absolute gas release from the undermined sources.

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 Methane Content Estimation in DuongHuy Coal Mine

2018 ◽  
Vol 35 ◽  
pp. 01005 ◽  
Author(s):  
Van Thinh Nguyen ◽  
Waldemar Mijał ◽  
Vu Chi Dang ◽  
Thi Tuyet Mai Nguyen
Keyword(s):  
Experimental Data ◽  
Coal Mining ◽  
Coal Mine ◽  
Coal Mines ◽  
Methane Content ◽  
Underground Coal Mining ◽  
Coal Seams ◽  
Underground Coal Mine ◽  
Different Depths ◽  
Quang Ninh

Methane hazard has always been considered for underground coal mining as it can lead to methane explosion. In Quang Ninh province, several coal mines such as Mạo Khe coal mine, Khe Cham coal mine, especially Duong Huy mine that have high methane content. Experimental data to examine contents of methane bearing coal seams at different depths are not similar in Duong coal mine. In order to ensure safety, this report has been undertaken to determine a pattern of changing methane contents of coal seams at different exploitation depths in Duong Huy underground coal mine.

scholarly journals Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wenyu Lv ◽  
Kai Guo ◽  
Jianhao Yu ◽  
Xufeng Du ◽  
Kun Feng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Maximum Deflection ◽  
Coal Seams ◽  
Physical Similarity ◽  
Working Face ◽  
Rock Structure ◽  
Backfill Mining ◽  
The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

scholarly journals Optimizing Simulation and Analysis of Automated Top-Coal Drawing Technique in Extra-Thick Coal Seams

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 232 ◽  
Author(s):  
Qunlei Zhang ◽  
Ruifu Yuan ◽  
Shen Wang ◽  
Dongyin Li ◽  
Huamin Li ◽  
...  
Keyword(s):  
Numerical Models ◽  
Time Estimation ◽  
Engineering Practice ◽  
Coal Seams ◽  
Control Approach ◽  
Working Face ◽  
Geological Conditions ◽  
Round Number ◽  
Element Approach ◽  
Drawing Technique

A particle element approach based on continuum-discontinuum element method (CDEM) is applied to optimize the automated top-coal drawing techniques in extra-thick coal seams. Numerical models with 100 drawing openings are created according to the field engineering geological conditions of Tongxin coal mine in China. An automated coal drawing control approach in numerical modelling based on time criterion is proposed. The rock mixed rate, top-coal recovery rate and the variance of the drawn top coal amount are counted and set as the statistical indicators to evaluate the top-coal drawing techniques. The traditional top-coal drawing criterion, “rocks appear, close the opening”, leads to low recovery of top coal and waste of coal resources in extra-thick coal seams, significantly weakening the transport stability and efficiency of the scraper conveyer. A three-round unequal time top-coal drawing technique is proposed for automated top-coal drawing. Three drawing openings, corresponding to the three top-coal drawing rounds respectively, are working at the same time; in each round, the top-coal drawing sequence is from the first drawing opening at one end of the working face to last drawing opening at another end; the drawing time of each round is not equal and increases with the round number. The numerical inversion approach of iteration steps can be used for real top-coal drawing time estimation and automated drawing process design to achieve a better top coal drawing effect, while the exact time for each drawing round still needs to be corrected by engineering practice.

scholarly journals The Stability of Gob-Side Entry Retaining in a High-Gas-Risk Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Junwen Zhang ◽  
Yulin Li
Keyword(s):  
Coal Mines ◽  
Surrounding Rock ◽  
Shanxi Province ◽  
Engineering Practice ◽  
Efficient Production ◽  
Coal Recovery ◽  
Working Face ◽  
Geological Conditions ◽  
The Stability ◽  
Strengthening Technique

There are series of problems faced by most of the coal mines in China, ranging from low-coal recovery rate and strained replacement of working faces to gas accumulation in the upper corner of coalfaces. Based on the gob-side entry retaining at the No. 18205 working face in a coal mine in Shanxi Province, theoretical analysis, numerical simulation, and engineering practice were comprehensively used to study the mechanical characteristics of the influence of the width of the filling body beside the roadway and the stability of surrounding rock in a high-gas-risk mine. The rational width of the filling body beside the roadway was determined, and a concrete roadway-side support with a headed reinforcement-integrated strengthening technique was proposed, which have been applied in engineering practice. The stability of the filling body beside the roadway is mainly influenced by the movement of the overlying rock strata, and the stability of the surrounding rock can be improved effectively by rationally determining the width of the filling body beside the roadway. When the width of the roadway-side filling body is 2.5 m, the surrounding rock convergence of the gob-side entry retaining is relatively small at only 5% of the convergence ratio. It has been shown that the figure for roof separation is relatively low, and strata behaviors are relatively alleviated and gas density do not exceed the limit, which are the best results of gob-side entry retaining. The results of this research can provide theoretical guidance for excavation of coal mines with similar geological conditions and have some referential significance to safety and efficient production in coal mines.

Mechanics of “Bumps” in Coal Mines: A Discussion of Violent Deformations in the Sides of Roadways in Coal Seams

1987 ◽  
Vol 40 (8) ◽  
pp. 1033-1043 ◽  
Author(s):  
Horst Lippmann
Keyword(s):  
Structural Model ◽  
Human Life ◽  
Coal Mines ◽  
Specific Property ◽  
Point Of View ◽  
Coal Seams ◽  
General Introduction ◽  
Recent Origin ◽  
Material Sciences ◽  
Physical Principles

Since long ago rock bursting has belonged to the most hazardous of events causing damage to material and loss of human life in underground cavities. Nevertheless, attempts to understand the physical principles of rock bursting from the point of view of the mechanical and material sciences seem to be of fairly recent origin. The following article deals especially with rock bursting in coal mines. After a general introduction, approaches based on a specific property of the excavated material called “proneness-to-bursting” are reviewed. This is followed by a survey of structural approaches to the problem. Finally, an elementary structural model is presented, leading to simple approximate conditions for the risk of initiating rock bursts, or for its efficiency.

Numerical Simulation of Underground Pressure in Mining High-Inclined Coal-Seam with Analysis of Material Properties in Mine Dongbaowei

2013 ◽  
Vol 644 ◽  
pp. 382-386 ◽  
Author(s):  
Ming Ming Wen
Keyword(s):  
Coal Seam ◽  
In Situ Observation ◽  
Coal Seams ◽  
Relevant Model ◽  
Roof Caving ◽  
Deformation Feature ◽  
Working Face ◽  
Strata Behavior ◽  
Surrounding Rock Stress

The FLAC software is used in establishing a relevant model to study the strata behavior of fully mechanized working face of steep coal seams. Using this model, we have simulated the roof caving characteristic and the stress distribution of surrounding rocks and analyzed the deformation feature of the surrounding rocks in the working face end. Based on the in-situ observation about the fully mechanized working face, we have obtained the surrounding rock stress and the strata behavior of steep coal seam and proposed some countermeasures aiming at these problems.

A Fast Geological Logging Technique of Underground Coal Mines Based on Photogrammetry

2013 ◽  
Vol 663 ◽  
pp. 661-667 ◽  
Author(s):  
Hao Li ◽  
Yun Cai ◽  
Biao Yang ◽  
Ming Fei Wu
Keyword(s):  
Image Processing ◽  
Information System ◽  
Information Processing ◽  
Coal Mines ◽  
Digital Camera ◽  
Work Efficiency ◽  
Fast Acquisition ◽  
Working Face ◽  
Underground Coal Mines ◽  
Computer Aided

Aiming at the deficiency of current geological logging method on the coal working face, the geological logging information system for coal mines based on digital camera is developed, integrating techniques of photogrammetry, graphic and image processing, and GIS. Emphasis is mainly placed on the fast acquisition of images from coal mining and excavation faces, photographic information processing and geological logging method, thus achieving the integrated work pattern of data acquisition, computer-aided processing and logging mapping. The experiment shows that by applying the fast geological logging technique of coal mines, the logging result which is accurate, authentic, reliable and satisfies the current requirements can be obtained, improving the work efficiency and result quality, therefore providing a new means and approach for geological logging of underground coal mines.

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