Mining Design Optimization Research on the Northern Section of 8 Coal Seam in West No.1 Mining Area in Pansan Mine

Water in Lower Aquifer of Quaternary is one of the mine water inrush sources during working faces being mining in the Northern Section of 8 Coal Seam in West No.1 Mining Area. Water flowing fractured zone, F1 fault, F22-a fault and F48 fault are main water-conducting channels in mining. According to the analysis of geology and hydrographical geology of the mine area, and combined with “Water Prevention Regulation of Coal Mines” and “Regulations of pillar leaving and coal mining under building, water, railway and mail shaft and tunnel”, stope layout was optimized, i.e. the minimum waterproof coal(rock) pillar between working face and Lower Aquifer Quaternary is 70 meter, the waterproof coal(rock) pillar between working face and F1 fault, F22-a fault, F48 fault is 70~95 meter, 70~75 meter, 80~90 meter respectively. Each shallow waterproof coal (rock) pillar of fault is narrow at the top and tends to increasingly widen at the bottom.

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A Mechanical Model of the Overlying Rock Masses in Undersea Coal Mining and a Stress-Seepage Coupling Numerical Simulation

Advances in Civil Engineering ◽

10.1155/2018/8161498 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 1

Author(s):

Jie Fang ◽

Lei Tian ◽

Yanyan Cai ◽

Zhiguo Cao ◽

Jinhao Wen ◽

...

Keyword(s):

Numerical Simulation ◽

Coal Seam ◽

Coal Mining ◽

Water Inrush ◽

Mining Area ◽

Analysis Model ◽

Fractured Zones ◽

Working Face ◽

Seam Mining ◽

Overlying Strata

The water inrush of a working face is the main hidden danger to the safe mining of underwater coal seams. It is known that the development of water-flowing fractured zones in overlying strata is the basic path which causes water inrushes in working faces. In the engineering background of the underwater mining in the Longkou Mining Area, the analysis model and judgment method of crack propagation were created on the basis of the Mohr–Coulomb criterion. Fish language was used to couple the extension model into the FLAC3d software, in order to simulate the mining process of the underwater coal seam, as well as to analyze the initiation evolutionary characteristics and seepage laws of the fractured zones in the overlying strata during the advancing processes of the working face. The results showed that, during the coal seam mining process, the mining fractured zones which had been caused by the compression-shear and tension-shear were mainly concentrated in the overlying strata of the working face. Also, the open-off cut and mining working face were the key sections of the water inrush in the rock mass. The condition of the water disaster was the formation of a water inrush channel. The possible water inrush channels in underwater coal mining are mainly composed of water-flowing fractured zones which are formed during the excavation processes. The numerical simulation results were validated through the practical engineering of field observations on the height of water-flowing fractured zone, which displayed a favorable adaptability.

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Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China

Geofluids ◽

10.1155/2021/6630462 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Zhengzheng Cao ◽

Yulou Ren ◽

Qinting Wang ◽

Banghua Yao ◽

Xinchao Zhang

Keyword(s):

Coal Seam ◽

Southwest China ◽

Water Inrush ◽

Mining Area ◽

Karst Collapse ◽

Coal Field ◽

Conducting Channel ◽

Evolution Mechanism ◽

Working Face ◽

Collapse Column

There are many karst collapse columns in coal seam roof in the southern coal field in China, which are different from those in coal seam floor in the northern coal field, due to the stratum characteristics. The karst collapse column in coal seam roof tends to reactivate and conduct water and induce the serious water inrush disaster, when the karst collapse column communicates with the overlying aquifer. In order to reveal the evolution mechanism of water-conducting channel of collapse column in karst mining area of southwest China, the aquifers and water inflow rule in 1908 working face in Qianjin coal mine are analyzed. Besides, the particle size distribution and mineral component of collapse column are researched by the X-ray diffraction test and the screening method, which are the basis for researching the water inrush mechanism in karst collapse column. On this basis, the water inrush of roof collapse column under the influence of mining is researched by establishing the numerical calculation model with the UDEC numerical software. The results show that the water flowing into the 1908 working face comes from the Changxing formation aquifer and Yulongshan formation aquifer above the coal seam, and the proportion of coarse particles and fine particles in collapse column is 89.86% and 10.14%, respectively. With the advance of working face, the water-conducting channel connected the working face with the aquifer, or the surface is formed by collapse pits, karst caves, and collapse column. The research results can be treated as an important basis for the water-preserved mining in southern coal field in China.

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Exploration and application of directional long boreholes in coal measure strata

E3S Web of Conferences ◽

10.1051/e3sconf/202126103003 ◽

2021 ◽

Vol 261 ◽

pp. 03003

Author(s):

Qin Ke ◽

Peng Dong ◽

Duan Huijun

Keyword(s):

Coal Seam ◽

Water Inrush ◽

Critical Value ◽

Coal Measure ◽

Bottom Plate ◽

Drain Water ◽

Safe Water ◽

Working Face ◽

Water Hazard ◽

Insulation Thickness

two roadways in adjacent working face of Baode Mine may have the risk of water inrush at the same time, so it is necessary to construct long borehole to cover the roadway excavation. On the basis of the hydrogeological conditions of the mine, the safe water insulation thickness and water inrush coefficient of coal seam No .8 are calculated. The results show that the water inrush coefficient is 0.035-0.037 MPa/m, which is less than the critical value 0.06 MPa/m and the bottom plate has no sudden water hazard. In the construction of No .10 coal seam, the directional long borehole is used to detect whether there is a hidden structure communicating with the floor limestone and to drain water. The test shows that there is no effluent phenomenon in the borehole, which proves that there is no hidden structure in No .10 coal seam.

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Computational fluid dynamics optimization of gas drainage technology in gas-mining areas

Energy Exploration & Exploitation ◽

10.1177/01445987211063586 ◽

2021 ◽

pp. 014459872110635

Author(s):

Wei Zhao ◽

Wei Qin

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Coal Seam ◽

Field Tests ◽

Mining Area ◽

Engineering Practice ◽

Horizontal Distance ◽

Gas Drainage ◽

Working Face ◽

Gas Seepage

Coal mining results in strata movement and surrounding rock failure. Eventually, manual mining space will be occupied by the destructed coal rock, making it difficult to conduct field tests of the coal seam to explore gas seepage and transport patterns. Therefore, computational fluid dynamics (CFD) numerical computation is an important tool for such studies. From the aspect of gas pre-drainage, for layer-through boreholes in the floor roadway of the 8,406 working face in Yangquan Mine 5 in China, reasonable layout parameters were obtained by CFD optimization. For effectively controlling the scope of boreholes along coal seam 9 in the Kaiyuan Mine, CFD computation was performed. The results revealed that the horizontal spacing between boreholes should be ≤2 m when a tri-quincuncial borehole layout is used. Optimization of the surface well position layout for the fault structure zone in the Xinjing Mine of the Yangquan mining area indicated that the horizontal distance between the surface well and the fault plane should be <150 m. From the aspect of gas drainage with mining-induced pressure relief, CFD computation was performed for pressure-relieved gas transport in the K8205 working face of Yangquan Mine 3. The results showed that forced roof caving should be used before the overhang length of hard roof reaches 25 m in the K8205 working face to avoid gas overrun. From the aspect of gas drainage from the abandoned gob, surface well control scopes at different surface well positions were computed, and an O-ring fissure zone is proposed as a reasonable scope for the surface well layout. CFD computation has been widely applied to coal and gas co-extraction in the Yangquan mining area and has played a significant role in guiding related gas drainage engineering practice.

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Hydrogeochemical Evolution and Control Mechanism of Underground Multiaquifer System in Coal Mine Area

Geofluids ◽

10.1155/2020/8820650 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Qiding Ju ◽

Yu Liu ◽

Youbiao Hu ◽

Yuquan Wang ◽

Qimeng Liu ◽

...

Keyword(s):

Cation Exchange ◽

Mine Water ◽

Control Mechanism ◽

Water Inrush ◽

Pyrite Oxidation ◽

Mining Area ◽

Carbonate Dissolution ◽

Mining Activities ◽

Hydrogeochemical Evolution ◽

And Control

Mining activities interfere into the natural groundwater chemical environment, which may lead to hydrogeochemical changes of aquifers and mine water inrush disasters. The study of hydrogeochemical evolution processes of underground aquifers is helpful to the prevention and control of mine water inrush. The results show that the study area is mainly impacted by four hydrogeochemical processes: dissolution, cation exchange, desulfurization and reduction, and pyrite oxidation. The Cenozoic aquifers are dominated by carbonate dissolution and desulfurization. The Permian aquifers are impacted mainly by cation exchange and sulfate dissolution, followed by pyrite oxidation. The Carboniferous aquifers are mainly impacted by dissolving sulfate, followed by pyrite oxidation and cation exchange. The hydrogeochemical evolution of the aquifers was controlled by mining activities and tectonic changes, and a certain regularity in space. For the Cenozoic aquifers, sulfate dissolution and cation exchange increase from west to east, and desulfurization weakens. For the Permian aquifers, cation exchange and sulfate dissolution are stronger near synclines and faults, pyrite oxidation is enhanced, and desulfurization decreases from the middle to the east of the mining area. For the Carboniferous aquifers, there is a higher dissolution of rock salt, pyrite oxidation, and cation exchange from west to east, and the desulfurization effect weakens.

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Study on the mechanism of water inrush in the arid western mining area

E3S Web of Conferences ◽

10.1051/e3sconf/201911803008 ◽

2019 ◽

Vol 118 ◽

pp. 03008

Author(s):

Chao Zheng ◽

Lan Yu ◽

Jiangyi He ◽

Fengfeng Yang ◽

Jufeng Zhang

Keyword(s):

Large Scale ◽

Water Pressure ◽

Water Inrush ◽

Hydrodynamic Pressure ◽

Mining Area ◽

Mining Areas ◽

Isolation Layer ◽

Working Face ◽

Combined Action ◽

Tension Fracture

The analysis found that the coal mining process in the western mining area has the mining loss and disaster effect of the water-rich aquifer of the coal seam roof, which is mainly manifested by the overburden water in the roof. On this basis, the formation and development of the separation water of the roof is proposed, and the mechanism of the water inrush from the layer is revealed. It is found that there is hydrostatic pressure and hydrodynamic pressure in the separated water, under the combined action of bed separation water pressure, the mining-induced fracture and water-isolation layer tension fracture are connected, which causes water inrushing in the coal working face of the mine, and provides a theoretical guarantee for the large-scale development of coal resources in western mining areas.

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Potential for mine water disposal in coal seam goaf: Investigation of storage coefficients in the Shendong mining area

Journal of Cleaner Production ◽

10.1016/j.jclepro.2019.118646 ◽

2020 ◽

Vol 244 ◽

pp. 118646 ◽

Cited By ~ 5

Author(s):

Hongqing Song ◽

Jianjian Xu ◽

Jie Fang ◽

Zhiguo Cao ◽

Lianzhi Yang ◽

...

Keyword(s):

Coal Seam ◽

Mine Water ◽

Mining Area ◽

Water Disposal

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Discrimination of Mine Water Bursting Source Based on Fuzzy System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.182-183.644 ◽

2012 ◽

Vol 182-183 ◽

pp. 644-648

Author(s):

Wei Feng Yang ◽

Ding Yi Shen ◽

Yu Bing Ji ◽

Yi Wang

Keyword(s):

Coal Mine ◽

Mine Water ◽

Fuzzy System ◽

Comprehensive Evaluation ◽

Water Inrush ◽

Fuzzy Comprehensive Evaluation ◽

Mining Area ◽

Shanxi Province ◽

Estimation Model ◽

Water Bursting

Through applying the background values of aquifer derived from fuzzy clustering analysis, a fuzzy comprehensive estimation model was developed for quick recognition of mine water inrush. Based on the hydrological-chemical analysis data of water samples which water bursting sources were known in Liliu mining area, Shanxi province, this paper presented that the hydrological-chemical characters of different aquifer was different, and established a sort of fuzzy comprehensive evaluation models of discriminating coal mine water bursting sources in Liliu mining area. Applied to a production mine, the correct rate of water bursting source judged results by various methods was more than 70%. With the dispersion method and the method extracted from stepwise discrimination analysis to determine the membership degree and Model 3 the type determined by various factors, the correct rate of water bursting source with comprehensive evaluation of combination of two methods was higher respectively 94.5% and 93.3%. The fuzzy system can efficiently and accurately discriminate the resource of water inrush for an unknown sample, and provide the decision basis for the safety production of the coal mine.

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Numerical Analysis of Stress Fields and Crack Growths in the Floor Strata of Coal Seam for Longwall Mining

Mathematical Problems in Engineering ◽

10.1155/2018/4012451 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Lingzhi Sun ◽

Yunyue Xie ◽

Hongtian Xiao

Keyword(s):

Coal Seam ◽

Crack Growth ◽

Water Pressure ◽

Water Inrush ◽

Coal Extraction ◽

Additional Stress ◽

Mining Activities ◽

Confined Aquifer ◽

Working Face ◽

Distribution Features

This paper predicts the possibility of water inrush from a confined aquifer under the action of mining activities and water pressure. The study uses numerical analyses to evaluate stress redistribution and crack growth which result from coal extraction operations. Two models are presented in this study. By simplifying the distribution of the disturbed vertical stress on the coal seam and floor around a working face, a model is established to analyze the additional stresses in the floor strata induced by mining activities. And some distribution features of all the additional stress components are described. By using the superposition principle in fracture mechanics, another model is developed to analyze the crack growth in the floor strata under the action of disturbed stresses and water pressure. And the stress intensity factors at the crack tip are presented and the process of crack growth is obtained in the advancement of a working face. Because of discretizing only loading areas and crack surfaces, the present methods can obtain the accurate numerical results. Finally, some suggestions are made for preventing the water inrush from a confined aquifer.

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Discussion on Advanced Seepage Reduction Characteristics of Working Face under Seepage-Damage Coupling

Shock and Vibration ◽

10.1155/2021/9299689 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Feisheng Feng ◽

Jiqiang Zhang ◽

Zhen Yang ◽

Dongdong Pang ◽

Jing Zhang

Keyword(s):

Stress Field ◽

Coal Seam ◽

Water Inrush ◽

Seepage Flow ◽

Mechanics Model ◽

Working Face ◽

Management Modes ◽

Reduction Characteristics ◽

Seam Mining ◽

Two Sectors

The water burst of roof on working face has been one of the significant geotechnical engineering problems that needs to be urgently resolved. The coupling effects of seepage and damage on the amount and intensity of water inrush from the roof are critically important. In this paper, the seepage-damage coupling mathematical model of the aquifer in the working face is studied, and the seepage-damage coupling mechanics model at different stages of the aquifer is established. Under the coupling of permeability and damage, the water-soil characteristics of the aquifer in the 101163 working face of Mindong were numerically simulated by establishing the constitutive relation between vertical stress and permeability coefficient. The numerical results show that the stress concentration factor of the mining stress field gradually increases with the coal seam mining. The water-flowing fractured zone of the overburden is close to the communication of the quaternary aquifer. When the coal seam is excavated 250–300 m. Three free surfaces appear in the groundwater pressure field, and a large falling funnel is formed to establish a deep flow S-well well flow model. The research on the mining stress field and seepage field is carried out in combination with the Jakob formula. It is found that two sectors with reduced permeability of the fan surface are formed in front of the work. The variation law of the apocalyptic permeability infiltration under different mining distances, different coal seam thicknesses, different water pressures, and different roof management modes is studied systematically. The research indicates that the seepage flow under the condition of seepage infiltration of the lower aquifer should be between 50% and 100% of the traditional calculation method. The research results can help to deepen the understanding of the process of water inrush under the coupling of stress and seepage.

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