Comparison study of "U+L" and "Y+L" working face ventilation patterns on gas control in a highly gassy mine

In order to solve the problem of pressure relief gas control under high-strength fully mechanized top-coal caving in low-gas-thick-coal seams, this paper studies the evolution of overburden structures and the distribution characteristics of fissure fields during the initial and stable period of working face by physical simulation and numerical analysis. The mathematical model of coupling between mining fracture field and pressure relief gas field is established. The results reveal the distribution characteristics of pressure relief gas field that considers mining-induced fissure field. According to the distribution of mining gas accumulation area, the high directional long boreholes have been put forward to control the pressure relief gas in goafs, and the effect has been tested. The results show that the initial pressure and three periodic pressures occurred from the cutting hole to 135 m in the initial mining period of the working face. The height of collapse zone developed to 22 m, and fracture height developed to 75 m. The development height of caving zone is stable at 25∼27 m, and the development height of fissure zone is stable at 75∼95 m. The process and distribution of pressure relief gas flow in goaf are obtained by solving the numerical model of pressure relief gas flow in mining fissure field. The gas accumulation area is located within 25∼55 m from return laneway and 25∼50 m from the roof of coal seam. After the implementation of high directional long drilling gas drainage technology in the initial mining period and the stable mining period, good results have been obtained in the gas control, where the average concentration of gas extraction is 5.8%, the average gas flow rate is 0.71 m3/min, and the gas concentration in upper corner and return air is less than 0.8%. The results can provide a reference for pressure relief gas control under similar conditions.

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Gas Control Technology under Unstable Disturbance Stress

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.15.26 ◽

2015 ◽

Vol 15 ◽

pp. 26-34

Author(s):

Wei Min Cheng ◽

Lu Lu Sun ◽

Gang Wang ◽

Hong Yuan Qu

Keyword(s):

Control Technology ◽

Static Loads ◽

Gas Drainage ◽

Gas Concentration ◽

Pressure Step ◽

Working Face ◽

Gas Control ◽

High Level ◽

Roadway Deformation ◽

Surrounding Rock Deformation

Under the action of unstable disturbance stress, the stress concentration and roadway deformation are serious when tunneling along the goaf with small pillar while the adjacent working face is mining. This leads to the abnormal gas discharge and the increase of gas emission, and the effectiveness of gas drainage is reduced. In order to eliminate the threat of gas, the dynamic gas control technology of tunneling along the goaf with small pillar under unstable disturbance stress has been researched. The main sources of loads are confirmed by the analysis of dynamic and static loads. Combined with the force analysis of roadway and pillar, the stress superposition level is affected by the relative location of heading face and working face, and the regional characteristics. The measured surrounding rock deformation of A4007 return roadway heading face fits the theoretical analysis and pressure step of working face. The dynamic gas control technology is researched from the aspects of air volume, high-level gas drainage and goaf drainage, and applied in A4007 working face. The gas has been well controlled with the gas concentration of top corner of 0.62% and gas concentration of return current of 0.35%. As a result of the flow control, the gas drainage has not casused spontaneous combustion.

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Study on Pre Pumping and Outburst Elimination Technology of “one hole and two elimination” in Bedding Directional Long Drilling

E3S Web of Conferences ◽

10.1051/e3sconf/202132901089 ◽

2021 ◽

Vol 329 ◽

pp. 01089

Author(s):

Benqing Yuan ◽

Yongjiang Zhang

Keyword(s):

Field Test ◽

Treatment Cycle ◽

Gas Treatment ◽

Gas Outburst ◽

Drainage Time ◽

Soft Coal ◽

Working Face ◽

Reasonable Range ◽

Gas Control ◽

Effective Drainage

Aiming at the problem of gas control in the working face and the roadway to be excavated at the same time due to the small construction length of bedding borehole under the condition of the occurrence of soft coal, a technology of "one hole and two elimination" pre-drainage to eliminate gas outburst by using air screw motor drilling was put forward, and the field test was carried out in the 17102(3) working face of Pansu Coal Mine.The results show that this technology can effectively control the borehole trajectory, ensure the uniform and reasonable range of borehole outburst elimination, solve the problems of long gas treatment cycle caused by the construction of gas treatment roadway, improve the effective drainage time of borehole, ensure enough time and space for gas treatment, and be beneficial to the mining and replacement of mine.

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Study on Gas Flow Law in Goaf of Huangling No.1 Mine Fully-Mechanized Face

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1010-1012.1548 ◽

2014 ◽

Vol 1010-1012 ◽

pp. 1548-1553

Author(s):

Tian Xuan Hao ◽

Meng Liu

Keyword(s):

Numerical Simulation ◽

Gas Flow ◽

Sampling Method ◽

Concentration Field ◽

High Fracture ◽

Gas Concentration ◽

Working Face ◽

Fluent Software ◽

Gas Control ◽

Important Basis

The gas concentration field in goaf of Huangling No.1 Mine 304 fully-mechanized face was simulated numerically by FLUENT software with high fracture drilling or not. The results of numerical simulation were confirmed by fixed sampling method of immersed tube in goaf. Thus, the law of gas concentration field was gained, which provides the important basis for gas control of working face.

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Goaf Gas Control Improvement by Optimizing the Adjacent Roadway Large-Diameter Boreholes

Advances in Civil Engineering ◽

10.1155/2021/1933010 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Wei Wang ◽

Zongxiang Li ◽

Hongming Yu

Keyword(s):

Gas Flow ◽

Large Diameter ◽

Control Process ◽

Utilization Efficiency ◽

Shanxi Province ◽

Engineering Practice ◽

Permeability Model ◽

Gas Concentration ◽

Working Face ◽

Gas Control

This study introduced gas control technology in goaf using adjacent roadway large-diameter (550 mm) boreholes to control gas accumulation in the upper corner of a fully mechanized working face in high-gas coal seams. The gas control process in the upper corner and gas interception in goaf by large-diameter boreholes was analyzed using the CFD model of the gas flow in goaf. The latter considered the control equation of gas flow, the established permeability model of goaf, and the gas emission law in goaf. Using the 2-105 working face of the Tenghui Coal Mine, Shanxi Province, China, as a case study, the distribution patterns of gas concentration and flow field in the goaf for various extraction flow parameters and different positions of boreholes were numerically simulated. The dependences between various locations, drainage flows, and the gas concentration in the upper corner were determined and fitted by engineering equations. The evolution pattern of the spontaneous combustion zone in the goaf under the drainage conditions was also analyzed. The optimal borehole configuration parameters ensuring the extraction flow rate exceeding 3 m·s−1 and the effective gas control in the upper corner of the working face at a distance of 5 m–15 m behind the working face were identified. The engineering practice proved the feasibility of gas control in the goaf using the adjacent roadway large-diameter borehole. The gas concentrations in the return airflow and the upper corner of the working face were kept below 0.65 and 0.8%, respectively, to ensure production safety and improve the gas utilization efficiency.

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