Numerical Simulation of Pressure Relief for Extremely Thin Coal Seam as Protection Seam Based on UDEC

2013 ◽  
Vol 295-298 ◽  
pp. 2879-2883
Author(s):  
Li Ming Zhang
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Protective Layer ◽  
Base Plate ◽  
Roof Displacement ◽  
Pressure Relief ◽  
Thin Coal Seam ◽  
The Face ◽  
High Concentrations ◽  
Overlying Strata

Overlying strata stress distribution, pressure relief region and crack distribution characteristics are analyzed based on numerical simulation of pressure relief with extremely thin coal seam as protection seam used by UDEC. The result is a true reflection of overlying strata movement and fissures for extremely thin coal seam as protection seam. Studies have shown that the roof displacement in the face of protective layer promoting is big, and as far away from the protective layer, the roof displacement is gradually reduced, the base plate displacement is almost the same, but the roof and floor to stress have been fully release; after protective layer mining, an "O" type pressure relief crack area is formed above the goaf, which is gas rich region and gas channels at the same time and suitable for extracting high concentrations gas.

scholarly journals Permeability Enhancement and Gas Drainage Effect in Deep High Gassy Coal Seams via Long-Distance Pressure Relief Mining: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xiang He ◽  
Ke Yang ◽  
Penghua Han ◽  
Wenjie Liu ◽  
Zhonghao Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Protective Layer ◽  
Enhancement Effect ◽  
Yield Model ◽  
Long Distance ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Permeability Enhancement ◽  
Seam Mining

Coal 3 in group A is employed as a protective layer to release long-distance coal 4 in group B in Paner colliery (approximately 80 m vertical interval) as the mining depth extends downward, which is the first engineering test in the Huainan coal mining area. To evaluate the validity of the scheme, the permeability distribution, and evolution law, gas pressure distribution characteristics, swelling deformation, pressure relief range, and gas drainage volume of the protected coal seam are analyzed using a FLAC3D numerical simulation and field measurements. Therefore, different stress-permeability models are adopted for caved, fractured, and continuous deformation zones, and a double-yield model is applied in the goaf based on compaction theory to improve the accuracy of the numerical simulation. The results indicate that the extraction of coal 3 has a positive effect on permeability enhancement and pressure relief gas drainage. However, the dip angle of coal measurements causes asymmetric strata movement, which leads to the pressure relief and permeability enhancement area shifting to the downhill side, where the permeability enhancement effect of the downhill side is better than that of the uphill side. The permeability enhancement zone is an inverted trapezoid, but the effective pressure relief range is a positive trapezoid. The permeability of the protected coal seam in the pressure relief zone is significantly higher than that in the compressive failure zone. The permeability in the pressure relief zone will decrease again due to the recompaction of the coal seam with an advancement of the longwall face. Thus, pressure relief gas drainage is suggested during long-distance protective coal seam mining to eliminate gas hazards.

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

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
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.

scholarly journals Study on Borehole Arrangement Methods for Gas Extraction by Hydraulic Slotting in Long-Distance Through-Coal Seam Tunnel

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Cunfang Zhu ◽  
Shuang Cai
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Simulation Models ◽  
Gas Production ◽  
Gas Extraction ◽  
Long Distance ◽  
Pressure Relief ◽  
Coal Deposits ◽  
Geological Conditions ◽  
Rapid Pressure

How to quickly eliminate outburst in long-distance through-coal seam tunnels is one of the major challenges faced by the tunnel industry in mountainous areas. Compared with coal mine rock crosscut coal uncovering, the work surrounding the rock of through-coal seam tunnels has a high degree of breakage, large cross-section of coal uncovering, and tight time and space. In this paper, a method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination is proposed. Based on this method, the corresponding mathematical governing equations and numerical simulation models have been established. The optimal borehole arrangement spacing and the slot arrangement spacing obtained by numerical optimization are 2.85 m and 3.1 m, respectively. Field gas production data of through-coal seam tunnels show that compared with the traditional dense-borehole gas extraction, the method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination can shorten the extraction time by about 66%, the net quantity of peak extraction is increased by 3.55 times, and the total quantity of gas extraction when reaching the outburst prevention index is increased by 1.26 times, which verifies the feasibility of this method and the reliability of numerical simulation results. This study could be used as a valuable example for other coal deposits being mined under similar geological conditions.

scholarly journals Study on the Evolution Law of Overburden Breaking Angle under Repeated Mining and the Application of Roof Pressure Relief

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4513 ◽  
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xingping Lai ◽  
Jiantao Cao ◽  
Pengfei Shan
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Theoretical Calculation ◽  
Simulation Experiment ◽  
Elevation Angle ◽  
Theoretical Formula ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Physical Similarity ◽  
Working Face

Aiming at the serious problems caused by coal mine mining activities causing the rock burst accidents, this paper is based on rock mechanics and material mechanics to establish the key layer breaking by the double-key layer beam breaking structural mechanics model of a single working face and double working face under repeated mining. The theoretical calculation formula of the angle was used as the theoretical basis for the elevation angle of the pre-reloading hole of the hard roof. The rationality and reliability of the formula were verified by the physical similarity simulation experiment and the 3 Dimension Distinct Element Code numerical simulation experiment, revealing the rock formation under the influence of repeated mining. The results show that the derived key layer breaking angle formula is suitable for the theoretical calculation of the breaking angle of the key layer of a single coal seam when the repeated disturbance coefficient is λ = 1; when it is λ = 2, it is suitable for the repeated mining of the short-distance double-coal mining. The rationality and reliability of the theoretical formula of the breaking angle of the double key layer of single coal seam and double coal seam were verified by the physical similarity simulation experiment. Through the 3DEC numerical simulation results and theoretical calculation results, the W1123 working face hard top pre-cracking pressure relief drilling elevation angle was 78°. The drilling peeping method was used to verify the results. The results show that the theoretical formula of the critical layer breaking angle is well applied in engineering practice.

Numerical simulation of pressure relief in hard coal seam by water jet cutting

2015 ◽  
Vol 8 (4) ◽  
pp. 495-510 ◽  
Author(s):  
Dazhao Song ◽  
Enyuan Wang ◽  
Jiankun Xu ◽  
Xiaofei Liu ◽  
Rongxi Shen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Water Jet ◽  
Hard Coal ◽  
Pressure Relief ◽  
Water Jet Cutting

Numerical Simulation of Roadway Deformation of Different Cutting Aperture

2013 ◽  
Vol 340 ◽  
pp. 892-895
Author(s):  
Xue Min Gong ◽  
Jia Yong Zhang ◽  
Li Wen Guo
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Wall Rock ◽  
Rock Stress ◽  
Analysis Software ◽  
Pressure Relief ◽  
Element Analysis ◽  
Gas Seepage ◽  
The Face ◽  
Roadway Deformation

Using ANSYS finite element analysis software, the crushing effect and wall rock deformation of a small high-pressure jet impacting coal were given numerical simulation analysis. It verified that impacting increased exposed area of coal in punch, providing conditions for pressure relief of internal coal seam and gas seepage. through comprehensive analysis of the rock stress and coal displacement of different roadway models after undercutting, it was determined that aperture size was 4/15 or so of roadway floor length, thus roadway fissures developed full, and maintained rock integrity, in favor of speeding up the face driving.

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