scholarly journals Control of the Internal and External Staggered Distance of Coal Mining Face to the Water-Conducting Fissures in the Overlying Strata of the Near Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhiyuan Jin ◽  
Tao Peng
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Calculation Formula ◽  
Coal Seams ◽  
Coal Face ◽  
Geological Conditions ◽  
Mining Face ◽  
Seam Mining ◽  
Water Proof

In Northwest China, rainfall is low, water resources are scarce, and the ecological environment is fragile. For shallow-buried and close-spaced coal seams with a thickness of upper coal bed >60∼70 m, the water-conducting fissures of the overlying rock will not penetrate the water-isolating layer after the upper coal seam is mined; the internal and external gap angles of the water-conducting fissures are not generated from the water-isolating layer. We set out to explore the critical internal and external dislocations for the second significant development of water-conducting fissures in the overlying rock after coal mining under control. A calculation model for the critical internal and external staggered distances of coal mining face in shallow-buried and close-spaced coal seams is established, the calculation formula is given, and the calculation formula for the critical seam mining ratio under the condition of internal staggered mining mode is given. Numerical simulation performed by UDEC methods: taking the overburden strata in the shallow-buried and close-spaced coal seam mining area of Shigetai Coal Mine as a prototype, it was verified that the critical internal and external offsets of the coal mining face in shallow-buried and close-spaced coal seams have a significant effect on the overlying water flow cracks in the mining of the lower coal seam. For the feasibility of developmental control, according to the engineering geological conditions of Shigetai, through the calculation method of external staggered distance, it is concluded that the distance of the open cut of the lower coal face and the upper coal face is only 21∼27 m, which is much smaller than the water barrier. It does not produce the critical distance of the water-conducting cracks. Therefore, in the process of mining the lower coal seam, the water-proof layer will produce water-conducting cracks, lose its water-proof performance, and cause water loss. This is also the cause of the water inrush accident in Shigetai Coal Mine.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

scholarly journals Height of the Fractured Zone in Coal Mining under Extra-Thick Coal Seam Geological Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Dequan Sun ◽  
Xiaoyan Li ◽  
Zhijie Zhu ◽  
Yang Li ◽  
Fang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Process Analysis ◽  
Failure Process ◽  
Analysis Method ◽  
Coal Seams ◽  
Fractured Zone ◽  
Seam Mining ◽  
Borehole Televiewer ◽  
Overlying Strata

The height of the fractured zone caused by coal mining is extremely significant for safely mining under water, water conservation, and gas treatment. At present, the common prediction methods of overburden fractured zone height are only applicable to thin and medium-thick coal seams, not suitable for thick and extra-thick coal seams. In order to determine the overburden fractured zone distribution characteristics of extra-thick seam mining, failure process analysis method of overlying strata was proposed based on key strata theory. This method was applied to 15 m coal seam of Tongxin coal mine, and fractured zone height was determined to be 174 m for 8100 panel. EH4 electromagnetic image system and borehole televiewer survey were also conducted to verify the theory results. The distribution of the electrical conductivity showed that the failure height was 150–170 m. Observation through the borehole televiewer showed that the fractured zone height was 171 m. The results of the two field test methods showed that the fractured zone height was 150–171 m, and it was consistent with the theory calculation results. Therefore, this failure process analysis method of overlying strata can be safely used for other coal mines.

Coal Seam Group Protection Layer Face Causes and Characteristics Analysis of Dynamic Phenomenon

2012 ◽  
Vol 550-553 ◽  
pp. 502-505
Author(s):  
Yong Jiang Zhang ◽  
Xian Zheng Meng ◽  
Zun Yu Xu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Protective Layer ◽  
Test Area ◽  
Mine Safety ◽  
Dynamic Phenomenon ◽  
Geological Conditions ◽  
Characteristics Analysis ◽  
Safety Production ◽  
Mining Face

In Xinji Coal Mine under complicated geological conditions, regional faults. Experimental zone for near coal seam group mining(6-1,7-1,7-2,8 seam), The objective conditions with protective layer . The minefield of soft broken coal seam, Soft layered coal firmness coefficient f = 0.18. In the test area of 210601,210603 6-1seam protective layer mining face during the period, there were 8 abnormal gas dynamic phenomenon, To the coal mine safety production brought hidden trouble. On the basis of dynamic phenomenon occurring phenomenon, analysis of the dynamic phenomena, combined with the test area actual situation, summed up the6-1coal power causes, for guiding the 6-1safety mining and provide a theoretical basis, has important significance.

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

Stress Shell Mechanical Mechanism of Fully-Mechanized Face Enhancing the Upper Limit for Coal Mining and Risk Analysis of Support Break-Off

2012 ◽  
Vol 524-527 ◽  
pp. 466-470
Author(s):  
Jun Ling Hou ◽  
Yan Sun
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mining ◽  
Surrounding Rock ◽  
Mechanical Environment ◽  
Upper Limit ◽  
Working Face ◽  
Distribution Rule ◽  
Geological Conditions ◽  
Mining Face

Based on the geological conditions and specific mining technology conditions of the 11014 mining face of Panbei mine in HuaiNan mining group ,using the FLAC3D software, simulate the stress distribution rule and disruption field distribution rule of surrounding rock of Fully-Mechanized face enhancing the upper limit for coal mining along the tendency and trend of coal seam by different mining speed of 6 m/d, 4 m/d and 2 m/d. draw the conclusion that enhancing the mining speed can alleviate the pressure of the working face ,improve the working face mechanical environment,and reduce the extent of the failure field.It provides the theory basis and reference for Fully-Mechanized face enhancing the upper limit for coal mining under similar conditions.

scholarly journals Fracture evolution and gas transport laws of coal and rock in one kilometer deep coal mine with complicated conditions

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 907-915
Author(s):  
Jianguo Zhang ◽  
Man Wang ◽  
Yingwei Wang
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Fracture Zone ◽  
Gas Flow ◽  
Gas Transport ◽  
Enhancement Effect ◽  
Gas Extraction ◽  
Coal Seams ◽  
Long Distance

As coal mining gradually extends deeper, coal seams in China generally show high stress, high gas pressure and low permeability, bringing more difficulty to coal mining. Therefore, in order to strengthen gas extraction, it is necessary to carry out reservoir reconstruction after deep coal seams reached. In this paper, the distribution and evolution laws of fracture zone overlaying strata of J15 seam in Pingdingshan No. 10 coal mine after excavation were studied by combining similar simulation and numerical simulation, meanwhile, the gas transport law within fracture zone was numerically simulated. The results show that the fracture zone reaches a maximum of 350 mm in the vertical direction and is 75 mm away from W9,10 coal seams in vertical distance. Since W9,10 coal seams are in an area greatly affected by the bending zone of J15 coal seam under the influence of mining, the mining of J15 coal seam will exert a strong permeability enhancement effect on W9,10 coal seams. The J15 coal seam can act as a long-distance protective layer of W9,10 coal seams to eliminate the outburst danger of the long-distance coal seams in bending zone with coal and gas outburst danger, thereby achiev?ing safe, productive and efficient integrated mining of coal and gas resources. The gas flux of mining-induced fractures in the trapezoidal stage of mining-induced fracture field is far greater than that in the overlaying stratum matrix. The horizontal separation fractures and vertical broken fractures within the mining-induced fracture field act as passages for gas-flow. Compared with gas transport in the overlaying stratum matrix, the horizontal separation fractures and vertical broken fractures within the mining-induced fracture field play a role in guiding gas-flow. The research results can provide theoretical support for the arrangement of high-level gas extraction boreholes in roof fracture zones.

scholarly journals Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
YingJie Liu ◽  
Qingjie Qi ◽  
Anhu Wang
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Rock Fracture ◽  
Mine Pressure ◽  
Overburden Rock ◽  
Coal Seams ◽  
Valley Bottom ◽  
Key Stratum ◽  
Seam Mining ◽  
The Impact

The absence of a key stratum during overburden rock movement is crucial to the mining pressure of fully mechanized coal mining faces. Using physical and numerical simulations, the 21304 mechanized mining in Daliuta and Huojitu coal mining faces 1−2 appeared twice during a pressure frame accident analysis. The results indicate that a lack of key overlying strata is crucial to the mining of lower coal seams, particularly for the upper sections of a single key stratum of coal. When the key stratum of the upper coal seam is absent, a stable masonry structure is formed after mining. It is easy to form stable stacked strata at the bottom of a coal seam. When developing gullies in deep terrains, the formation of the key stratum will be an upper rock fracture affected by the impact, resulting in a partial absence of the key stratum. When the key stratum is absent, the mining of upslope working faces and the probability of dynamic strata pressure increase with the overburden on the working face and mining of downslope faces. The face mine pressure development laws on the upper and lower coal seam mining were similar, mainly manifesting as “slope section >valley bottom section >back slope section.”

Recent Patents on Thin Coal Seam Mining Equipment

2020 ◽  
Vol 13 (2) ◽  
pp. 99-108
Author(s):  
Yanxiang Wang ◽  
Daolong Yang ◽  
Bangsheng Xing ◽  
Tingting Zhao ◽  
Zhiyi Sun ◽  
...  
Keyword(s):  
Coal Seam ◽  
Underground Space ◽  
Mining Method ◽  
Mining Equipment ◽  
Coal Seams ◽  
Thin Coal Seam ◽  
Recoverable Reserves ◽  
Working Face ◽  
Geological Conditions ◽  
Seam Mining

Background:: China's thin and extremely thin coal seam resources are widely distributed and rich in reserves. These coal seams account for 20% of the recoverable reserves, with 9.83 billion tons of industrial reserves and 6.15 billion tons of recoverable reserves. Objective: Due to the complex geological conditions of the thin coal seam, the plow mining method cannot be effectively popularized, and the drum mining method is difficult to be popularized and applied in small and medium-sized coal mines, so it is necessary to find other more advantageous alternative mining methods. Methods: The equipment integrates mining operations, conveying operations, and supporting operations, and is suitable for mining short and extremely thin coal seam with a height of 0.35m-0.8m and width of 2m-20m. It has the advantages of the low body of the shearer, no additional support on the working face, and small underground space. The mining efficiency of thin coal seam and very thin coal seam can be improved and the mining cost can be reduced. Results: Thin coal seam shear mining combines mining, conveying, and supporting processes together and has the advantages of a low fuselage, no extra support required for the working face, and feasibility in a small underground space. Conclusion: The summarized mining method can improve the mining efficiency of thin and extremely thin coal seams, reduce mining costs, and incorporate green mining practices, which take both mining economy and safety into account.

Research on the Overlying Strata in Full-Mechanized Coal Mining of Datong Jurassic Coal Multi-Layer Goaf

2012 ◽  
Vol 616-618 ◽  
pp. 402-405 ◽  
Author(s):  
Hong Chun Xia ◽  
Guo Sheng Gao ◽  
Bin Yu
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Pillar ◽  
Mining Area ◽  
Mechanics Model ◽  
Roof Structure ◽  
Geological Conditions ◽  
Seam Mining ◽  
The Impact ◽  
Overlying Strata

According to the specific geological conditions in themulti-layer worked-out areas of Yongding coal seam, by the methods of integration of theoretic analysis, numerical value calculation and so on, we studied movement law of Overlaying Strata and influence of coal pillar in Coal seam mining, obtained the basic law of the overlying strata movement in multiplayer, provides a theoretical basis for the safe and efficient exploitation of the success of multiplayer. Many mining area in China is mining of closed distance coal seam group, By the impact of coal seam in the overlying, face and the tunnel roof structure will be different injury in sub-coal seam mining, Roof structure has changed greatly, even damage and easily take the roof leakage, When the the goaf communication with the overlying coal seams, caused by the induced secondary disasters such as face air leakage, Therefore, exploitation of the law of motion of the overlying strata in the multiplayer is a pressing problem. Exploitation multiplayer seam few theoretical and technical foundation at home and abroad, affecting the validity of the mining, rationality. although a lot of research on theory and technology of coal mining over the years[1~5], But it was not able to an overall comprehensive analysis of upper goaf adjacent goaf and overlying the coal pillar and present mining face, create a dynamic structural mechanics model, which is likely to cause the occurrence of disasters.

Automated Technology Research on Fully Mechanized Mining of Thin Coal Seams

2013 ◽  
Vol 774-776 ◽  
pp. 1453-1457
Author(s):  
Bu Qin Zhang ◽  
An Qi Li
Keyword(s):  
Remote Control ◽  
Coal Seam ◽  
Coal Mining ◽  
Technology Research ◽  
Video Technology ◽  
Coal Seams ◽  
Coal Face ◽  
Thin Coal Seam ◽  
Automated Technology ◽  
Automation Technology

Research on automation technology of thin coal seam based on the specific conditions of Xuecun mine achieves mechanization and automation of coal mining processes; coal or rock identification monitoring based on reliable video technology; remote control to adjust the guidance of surface operations and memory automatically cutting unmanned management of the coal face.

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