Protection scope and gas extraction of the low-protective layer in a thin coal seam: lessons from the DaHe coalfield, China

Cao, Zuoyong; He, Xueqiu; Wang, Enyuan; Kong, Biao

doi:10.1007/s12303-017-0061-1

Cited by 20 publications

(13 citation statements)

References 19 publications

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“…Generally, adopting eld-testing to determine the protection range along an inclination requires drilling boreholes for measurement of parameters including gas pressure, gas content and maximum expansion deformation rate of the protected seam, etc. (Cao et al, 2018;Jin et al, 2016;Li et al, 2014;Liu et al, 2017;Xue and Yuan, 2017;Yuan and Xue, 2014). DRPCGO also emphasizes that historical data reference can be applied to estimate the effective protected zone when there is no eld-testing data or the rst time to exploit the protective seam in a coal mine (Safety, 2019).…”

Section: Detailed Rules On Prevention Of Coal and Gas Outburst (Drpcgmentioning

confidence: 99%

Mathematical equations for pressure relief angle of protective seam inclination in outburst coalmine

Zhang

Liu

Ren

et al. 2020

Preprint

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Protective seam mining is one kind of most effective measure to reduce coal and gas outburst risk. The pressure relief angles along inclination (δm) are key parameters for evaluating the effect of protective seam mining. However, the numerical relation between δm and coal seam dip (a) is defined by discrete data and is difficult to determine δm accurately. In this study, the variations of δm with respect to seam dips are analyzed to derive analytical equations that can be used to accurately calculate δm. The relationship between δm and seam dip (a) can be expressed as parabolic or inverted parabolic curves. Mathematical equations for δm are derived by curve fitting technique. Furthermore, polynomial equations are determined as the most appropriate for δm calculation when the polynomial order is selected as 7, 6, 4 and 5 respectively. These derived equations are computationally solved and verified using actual and field test data of δm. with satisfactory consistency and accuracy. The equations are suggested as supplement and improvement for Detailed Rules on Prevention of Coal and Gas Outburst.

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Section: Detailed Rules On Prevention Of Coal and Gas Outburst (Drpcgmentioning

confidence: 99%

Mathematical equations for pressure relief angle of protective seam inclination in outburst coalmine

Zhang

Liu

Ren

et al. 2020

Preprint

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“…Qin et al [18] believed the computational fluid dynamics (CFD) is the optimized method for coal seam gas drainage design. Cao et al [19] used a numerical model to simulate the stressstrain relationship in the lower protective coal seam during the protective coal seam mining operation and hence mapped out the stress relief zone which was further validated by theoretical approaches. Xue et al [20] investigated the stress relief and permeability increase in the protective coal seam during mining operation and hence developed physical models that capture subsidence zone and fracture distribution zone in the protective coal seam.…”

Section: Introductionmentioning

confidence: 99%

Stress Distribution and Gas Concentration Evolution during Protective Coal Seam Mining

Niu

Shi

Zhang

et al. 2021

Advances in Civil Engineering

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Coal and gas burst is one of the significant and catastrophic hazards in underground longwall operations. To date, the protective coal seam mining has been recognized as the most effective mining method for minimizing or even avoiding the effect of the coal and gas burst. In this paper, numerical modelling and field test were carried out for the longwall operation in Qidong Coal Mine in order to investigate the induced stress and coal seam gas drainage performance in the protected coal seam after the complete extraction of the protective coal seam. It was found that four stress zones can be classified in the protected coal seam being the original stress zone, stress concentration zone, stress relief zone, and recompaction zone. In addition, the monitoring data of gas concentration and volume change in the field agree well with the numerical modelling results.

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“…ey indicated that the stress and gas pressure of the protected coal seam decreased significantly with the remote upper protective layer mining. Cao et al [32] simulated the stress and displacement field of the protected layer under the lower protective coal seam mining. ey acquired the evolution law of the stress and displacement field of the protected layer.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Similarity Simulation Study on the Protection Effect of Composite Protective Layer Mining with Gently Inclined Thick Coal Seam

Hou

Jiang-tao

2021

Shock and Vibration

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Protective layer mining, as a dominating method for preventing coal and gas outburst, is generally adopted in highly gassy coal mines. In the absence of a suitable thickness coal seam to serve as the protective layer, the rock-coal composite protective layer was proposed in this paper. We conducted a series of simulations and engineering measurements to investigate the protective effect under the mining of the rock-coal composite protective layer of the Zhongtai coal mine located in the Hebi area of Henan, China. The numerical simulation analysis showed that, after the completion of protective layer mining, the minimum vertical stress of the No. 2-1 coal seam had been reduced to 3.46 MPa. The maximum vertical displacement of the No. 2-1 coal seam is 455.01 mm. The maximum expansion deformation of the No. 2-1 coal seam is 9.77‰; the effective pressure relief range is as long as 160 m. The similarity simulation experiment revealed that, after the completion of protective layer mining, the minimum vertical stress of the No. 2-1 coal seam is 4.0 MPa. The maximum vertical displacement of the No. 2-1 coal seam is 640 mm. The maximum expansion deformation of the No. 2-1 coal seam is 26.37‰; the effective protection range reaches 130 m. The engineering measurements demonstrated that the variation law of gas drainage parameters in the protected layer corresponds to the protected layer's vertical stress distribution law in numerical simulation and similarity simulation. With the exploitation of the composite protective layer, the protective layer’s pressure begins to release. The average gas drainage concentration is 2-3 times of that before the composite protective layer mining.

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Protection scope and gas extraction of the low-protective layer in a thin coal seam: lessons from the DaHe coalfield, China

Cited by 20 publications

References 19 publications

Mathematical equations for pressure relief angle of protective seam inclination in outburst coalmine

Mathematical equations for pressure relief angle of protective seam inclination in outburst coalmine

Stress Distribution and Gas Concentration Evolution during Protective Coal Seam Mining

Numerical and Similarity Simulation Study on the Protection Effect of Composite Protective Layer Mining with Gently Inclined Thick Coal Seam

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