The numerical simulation of permeability rules in protective seam mining

2016 ◽  
Vol 13 (3) ◽  
pp. 243 ◽  
Author(s):  
Cun Zhang ◽  
Shihao Tu ◽  
Lei Zhang ◽  
Fangtian Wang ◽  
Qingsheng Bai ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Protective Seam ◽  
Seam Mining ◽  
Protective Seam Mining

scholarly journals Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Jiaxin Dang ◽  
Min Tu ◽  
Xiangyang Zhang ◽  
Qingwei Bu
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Expansion Ratio ◽  
Pressure Relief ◽  
Protection Effect ◽  
Protective Seam ◽  
Coal Wall ◽  
Seam Mining ◽  
Protective Seam Mining ◽  
Relief Effect

Protective seam mining is an effective gas pressure relief method in deep mining. Effective theoretical calculation methods in the current studies on the prediction of pressure relief protection effect of interbed coal and rock masses and their distribution laws are lacking. Thus, the evaluation and research with respect to pressure relief effect in protective seam mining relatively lag behind. This situation restricts the engineering feasibility evaluation and decision making in the protective seam mining. Therefore, the influence of upper protective seam mining on the pressure relief protection effect of coal and rock mass between underlying beds was investigated in this study. On the basis of an analysis of concrete engineering projects, a mechanical model was constructed for the pressure relief protection effect of upper protective seam mining on the coal and rock mass between underlying beds. The distribution equation of pressure relief expansion ratio in the underlying protected seam was also derived. The influence laws of main influencing factors on the pressure relief protection effect of the protected seam were revealed as well. In the end, the pressure relief effect was analyzed and verified for the protected seam before and after mining through numerical simulation and similarity simulation test. The pressure relief effect of upper protective seam mining on the coal and rock mass between underlying beds and the distribution characteristics were deeply explored in this study, which could provide a theoretical reference for the decision making in the gas extraction engineering design and pre-evaluation of extraction effect. Results show that the effective pressure relief zone (expansion rate>0.3%) of the protected seam beneath the goaf is located within the range of approximately 40 m from the coal wall to the rear part. It also presents an approximate “Λ-shaped distribution characteristic,” that is, it experiences migration and evolution with the advancement in the working face. Moreover, the peak pressure relief lags behind the coal wall on the working face by nearly 10–20 m. In the numerical simulation, the expansion ratio in the goaf also presents an approximate “Λ-shaped distribution.” Its effective pressure relief zone is the 50 m range from the coal wall to the rear part of the goaf, and the peak value lags behind the coal wall by around 15 m. The theoretical results and numerical simulation results are basically consistent with the physical experiment results. The expansion rates are 1.25%, 1.268%, and 1.32%, respectively. The elastic modulus E of coal seam and interbed spacing H are the main influencing factors of the swelling deformation and are negatively correlated with the expansion ratio. In the actual mining process, E and H of the protected layer can be measured to infer the expansion deformation of the protected layer.

The numerical simulation of permeability rules in protective seam mining

2016 ◽  
Vol 13 (3) ◽  
pp. 243
Author(s):  
Qingsheng Bai ◽  
Fangtian Wang ◽  
Hongsheng Tu ◽  
Lei Zhang ◽  
Cun Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Protective Seam ◽  
Seam Mining ◽  
Protective Seam Mining

scholarly journals Reduction of Stress Acting on a Thick, Deep Coal Seam by Protective-Seam Mining

Energies ◽  
2017 ◽  
Vol 10 (8) ◽  
pp. 1209 ◽  
Author(s):  
Rui Gao ◽  
Bin Yu ◽  
Hongchun Xia ◽  
Hongfei Duan
Keyword(s):  
Coal Seam ◽  
Protective Seam ◽  
Seam Mining ◽  
Protective Seam Mining

scholarly journals Acoustic Emission Characteristics of Coal Samples under Different Stress Paths Corresponding to Different Mining Layouts

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3295
Author(s):  
Yiming Yang ◽  
Ting Ai ◽  
Zetian Zhang ◽  
Ru Zhang ◽  
Li Ren ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Deep Mining ◽  
Ae Energy ◽  
Working Face ◽  
Mining Conditions ◽  
Protective Seam ◽  
Order Of Magnitude ◽  
Three Stages ◽  
Seam Mining ◽  
Protective Seam Mining

Research on the mining-induced mechanical behavior and microcrack evolution of deep-mined coal has become increasingly important with the sharp increase in mining depth. For rock units in front of the working face, the microcrack evolution characteristics, structural characteristics, and stress state correspond well to mining layouts and depths under deep mining. The acoustic emission (AE) characteristics of typical coal under deep mining were obtained by conducting laboratory experiments to simulate mining-induced behavior and utilizing AE techniques to capture the variation in AE temporal and spatial parameters in real time, which provide an important basis for studying the rupture mechanisms and mechanical behavior of deep-mined coal. The findings were as follows: (1) AE activity under deep mining was characterized by three stages, corresponding to crack initiation, crack stable propagation, and crack unstable propagation. As the three stages proceeded, the AE counting rate and AE energy rate presented stronger clustering characteristics, and the cumulative AE counting and cumulative AE energy exhibited a sharp increase by an order of magnitude. (2) The crack initiation and the main stages of crack propagation were determined by characteristic points of variation curves in the AE parameters over time. In the main crack propagation stage, the number of cumulative AE events and the cumulative AE counts were similar among the three mining conditions, while coal samples under coal pillar mining released the largest amount of AE energy. The amount of accumulated AE energy released by coal samples increased by one order of magnitude according to the sequence of protective coal-seam mining, top-coal caving mining, and nonpillar mining. (3) Fractal technology was applied to quantitatively analyze the AE spatial evolution process, showing that the fractal dimension of the AE location decreased as the peak stress increased, corresponding to protective seam mining, caving-coal mining, and nonpillar mining. The above results showed that the deformation and fracture characteristics of coal under deep mining followed a general law, but were affected by different mining conditions. The crack initiation and main rupture activity of coal occurred earlier under the conditions of protective seam mining, top-coal caving mining, and nonpillar mining, successively. Moreover, nonpillar mining induced the strongest and highest degree of unstable rupture of the coal body in front of the working face.

scholarly journals Key technologies and engineering practices for soft-rock protective seam mining

2020 ◽  
Vol 30 (6) ◽  
pp. 889-899
Author(s):  
Xiang Cheng ◽  
Guangming Zhao ◽  
Yingming Li ◽  
Xiangrui Meng ◽  
Qingyi Tu
Keyword(s):  
Soft Rock ◽  
Key Technologies ◽  
Protective Seam ◽  
Seam Mining ◽  
Protective Seam Mining ◽  
Engineering Practices

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

2020 ◽  
Author(s):  
Zhen Zhang ◽  
Gaofeng Liu ◽  
Ting Ren ◽  
Patrick Booth ◽  
Runsheng Lv ◽  
...  
Keyword(s):  
Coal And Gas Outburst ◽  
Pressure Relief ◽  
Effective Measure ◽  
Gas Outburst ◽  
Relief Angle ◽  
Protective Seam ◽  
Mathematical Equations ◽  
Seam Mining ◽  
Protective Seam Mining ◽  
The Relationship

Abstract 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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