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

Gao, Rui; Yu, Bin; Xia, Hongchun; Duan, Hongfei

doi:10.3390/en10081209

Cited by 22 publications

(11 citation statements)

References 22 publications

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“…e phenomenon of slight lifting of thick conglomerate in a short time is directly verified by the surface uplift movement of adjacent monitoring. e most direct influence of conglomerate's uplift on coal and rock mass is the change of vertical stress environment of coal body, and the vertical stress environment is the key factor restricting the horizontal 10 Advances in Civil Engineering slip of coal body. During the time when the thick conglomerate shows comovement effect, the horizontal bump of the coal body is easy to occur, and the hydraulic props slides in in the horizontal direction under the influence of coal sliding.…”

Section: Discussionmentioning

confidence: 99%

“…For the evolution of overburden structure, there is a great difference in breaking mode with near field and far field [10][11][12], and in strata behavior of working face and goaf roadway with different thickness, strength, and height of key roof strata [13,14]. High strength of direct roof mediumthick strata, large thickness, and low strata lead to high roof pressure [15,16].…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of Coal Bump among Mine Group under the Control of Large Geological Body: A Case Study of Yima Mining Area, China

Zhao

et al. 2021

Advances in Civil Engineering

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Coal bump often occurs in coal mining among many working faces in mine group under the control of large geological bodies. In order to study the coal bump mechanism between adjacent working faces under the conditions of large fault and huge thick overburden conglomerate, this paper regards Yima mining area as a practical engineering background and theoretically analyzes the mechanical behavior of overlying rock in the spatial structure. Then, the deep-ground and whole-space measurement is carried out in the 13230 working face of Gengcun mine and 21121 working face of Qianqiu mine. The results show that the basic structural unit in Yima mining area is composed of two goafs, middle coal pillar, and overlying conglomerate. Under the condition of nonsynchronous mining in adjacent working faces, there is a comovement effect similar to lever’s “prying” phenomenon in thick conglomerate beam—the conglomerate strata above larger goaf side induce an overall uplift movement of the corresponding strata above smaller goaf side, and uplift length of the conglomerate strata is related to the mining length, coal pillar width, caving angle, and coal-conglomerate distance. The results of surface subsidence, microseism, and stress in the two working faces verify the conglomerate’s phenomenon of comovement effect and disturbance range and further explain the role of active movement of F16 fault and overall causes of huge thick conglomerate on the coal bump. The vertical stress of the 13230 face is relatively low at the beginning, and high horizontal stress by fault activation causes typical bump accident with the horizontal sliding of coal body. With the increasing development of 13230 face, the intensity and frequency of coal bump in horizontal direction decrease obviously, but with high proportion in vertical direction. The results provide a theoretical basis for the study on the mechanism of coal bump between two adjacent working faces under the conditions of huge thick conglomerate and large thrust fault.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of Coal Bump among Mine Group under the Control of Large Geological Body: A Case Study of Yima Mining Area, China

Zhao

et al. 2021

Advances in Civil Engineering

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“…Li et al [ 45 ] used a numerical simulation method to study the surface settlement during strip mining with different coal pillar widths. Through similarity model experiments and numerical simulations, Gao et al [ 46 ] studied the change law of overburden stress after protective layer mining. Dong et al [ 47 ] studied coal and gas outburst control by protective coal seam mining based on numerical simulation and related theories.…”

Section: Introductionmentioning

confidence: 99%

The pressure relief protection effect of different strip widths, dip angles and pillar widths of an underside protective seam

et al. 2021

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To design underside protective seam strip layout. Similarity model experiments, numerical simulations and theoretical calculations are used to quantitatively study the pressure relief protection effect of different strip widths, dip angles and coal pillar widths of a thin underside protective seam under deeply buried conditions. The optimal strip width range is obtained according to the change law of strain during the mining process of the underside protective seam in a similar model experiment. The change law of the expansion of the protected coal seam is obtained and the fitting surfaces among the dip angle and strip width of the coal seam with the protection distance and pressure relief angle along the strike and dip of the protected coal seam are established according to the numerical simulation results of underside protective seam mining. It is concluded that the best pressure relief effect can be achieved when the dip angle is 16.7° and the strip width is 70 m. According to the stability threshold of coal pillars considered in strip mining theory, the coal pillar width is calculated to be 50 m. Similarity model experiments and numerical simulations of protected coal seam mining verify the pressure relief effect of the designed protective seam strip width and pillar width. A calculation method of the protective seam strip width, position and pillar width required by the specific width of the protected seam is proposed.

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“…27 At present, the methods for determining the protection range mainly include numerical simulations, on-site testing, reference to the RPCGOB in China, and physical simulations. 18,19,28,29 Each method has its own advantages and disadvantages. The numerical simulation method has difficulty fully considering the characteristics of the fracture development in the surrounding layers as the PCL working face is…”

Section: Introductionmentioning

confidence: 99%

Physical simulation of upper protective coal layer mining with different coal seam inclinations

Fang

Shu

Wang

2020

Energy Science & Engineering

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Protective coal layer (PCL) mining is a preferred regional method for preventing coal and gas outbursts; stress‐relief of PCL mining is the prerequisite of pressure‐relief gas drainage. In order to study the stress‐relief effect of PCL mining on protected coal seams and determine the protection scope of PCL mining under different inclinations, this paper uses physical simulations to study the stress‐relief law and deformation characteristics of the strata during upper PCL mining with a gentle inclination (25°), an intermediate inclination (45°), and a steep inclination (65°). The results show that as the coal seam dip increases, the degree of deformation and failure of the overburden strata gradually decreases, the severe subsidence and expansion area of the overburden strata tends to gradually develop in the uphill direction of the working face, and the floor strata underlying the protective seam significantly expand toward the goaf. However, the absolute value of the upward movement of the floor strata is much smaller than that of the roof strata; and the greater the dip angle, the greater the ratio of floor displacement to roof subsidence. The stress‐relief curve of the protected layer is approximately U‐shaped. As the inclination of the coal seam increases, the stress‐relief range decreases gradually. The maximum relief‐stress and the stress release coefficient of the protected layer initially increase and then decrease. The stress concentration coefficient of the protected coal seam initially increases first and then decreases in both uphill and downhill of the working face in the PCL. As the inclination increases, the stress‐relief angle of the downhill boundary initially increases and then decreases, while the stress‐relief angle of the uphill boundary decreases gradually. Our research results provide guidance for the delimitation of the protected scope of PCLs with different dip angles.

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

Cited by 22 publications

References 22 publications

Mechanism of Coal Bump among Mine Group under the Control of Large Geological Body: A Case Study of Yima Mining Area, China

Mechanism of Coal Bump among Mine Group under the Control of Large Geological Body: A Case Study of Yima Mining Area, China

The pressure relief protection effect of different strip widths, dip angles and pillar widths of an underside protective seam

Physical simulation of upper protective coal layer mining with different coal seam inclinations

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