Vibration Analysis of a Three-Drum Shearer for a Large Mining Height

Ultra-thick hard sandstone roofs present high thickness, poor delamination, and wide caving range. The strata pressure of the working face during actual mining increases, having a significant influence on the safe mining of the working face. Especially, in the mining areas of western China, the fully mechanized mining faces with high mining height and high-strength mining are more prominent. Understanding the fractures and stress evolution characteristics of the ultra-thick hard sandstone roof during actual mining is of high significance to control the dynamic pressure on the working face. In this paper, the typical ultra-thick hard sandstone roof of the Xiaojihan coal mine was taken as an example. The structural and chemical composition characteristics were analyzed. Besides, the fracture characteristics of ultra-thick hard roof during the working face mining were analyzed. Moreover, the fracture structure consistency was verified through physical simulation and a field measurement method. Finally, the stress evolution laws in the ultra-thick hard sandstone roof fracture were studied through numerical simulation. The findings demonstrated that (1) the ultra-thick hard sandstone roof was composed of inlaid coarse minerals, which had compact structure, while the Protodyakonov hardness reached up to 3.07; (2) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof had the characteristics of brittle fracture, with a caving span of 12 m; (3) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof followed the stress evolution laws that were more sensitive to the neighboring goaf. Therefore, it was necessary to reduce the fracture span or layering of ultra-thick hard sandstone roof through the manual intervention method adoption or increase either the strength of coal pillar or supporting body, to resist the impact generated during ultra-thick hard sandstone roof fracture.

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Determination of Optimal Extrication Location of High Extraction Roadway of Large-Mining-Height Fully Mechanized Face

Advances in Civil Engineering ◽

10.1155/2018/5145746 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

Xue-bo Zhang ◽

Ming Yang

Keyword(s):

Gas Extraction ◽

Horizontal Distance ◽

High Position ◽

Working Face ◽

Extraction Site ◽

Large Mining Height ◽

Porosity And Permeability ◽

Permeability Distribution ◽

Mining Height

Determining the optimal extrication location of the high extraction roadway can improve the gas extrication effect of highly gassy mine and solve the problem of gas concentration overrun at the upper corner, which is of great significance to safety and efficient mine production. According to the actual situation of mine, the gas gushing amount in the goaf, pressure difference at both ends of the working face, the 3D porosity, and permeability distribution of the caving zone and fissure zone were obtained by field measurement and numerical calculation. Through theoretical calculation, the proper extraction site of a high-position alley was determined. On this basis, the optimal extraction site of a high-position alley was determined by numerical analysis of the gas extraction effect at different sites. The results show that as the perpendicular distance between high-position alley and goaf floor increases, the gas extraction amount increases first and then decreases. The concentration of extraction gas gradually increases, and the increasing trend is gradually diminished. With the increase of the horizontal distance between the air return way and the high-position alley, the gas extraction amount and gas extraction concentration increase first and then decrease. The optimal extraction site of a high-position alley should be 39 m vertically away from the goaf floor and 30 m horizontally away from the air return way.

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Deformation characteristics and stability control of a gateroad in fully mechanized mining with large mining height

Arabian Journal of Geosciences ◽

10.1007/s12517-018-4087-0 ◽

2018 ◽

Vol 11 (24) ◽

Cited By ~ 3

Author(s):

Hong-hu Yuan ◽

Ren-liang Shan ◽

Xue-gui Su

Keyword(s):

Stability Control ◽

Deformation Characteristics ◽

Large Mining Height ◽

Mining Height

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Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

Energy Science & Engineering ◽

10.1002/ese3.307 ◽

2019 ◽

Vol 7 (3) ◽

pp. 777-798 ◽

Cited By ~ 11

Author(s):

Bo Li ◽

Yunpei Liang ◽

Quanle Zou

Keyword(s):

Key Stratum ◽

Large Mining Height ◽

Movement Type ◽

Working Resistance ◽

Mining Height

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Research on Surface Failure Law of Working Faces in Large Mining Height and Shallow Buried Coal Seam

Advances in Civil Engineering ◽

10.1155/2020/8844249 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Zhenhua Li ◽

Yingkun Pang ◽

Yongsheng Bao ◽

Zhanyuan Ma

Keyword(s):

Near Field ◽

Mining Area ◽

Surface Cracks ◽

Large Space ◽

Key Strata ◽

Key Stratum ◽

Surface Failure ◽

Working Face ◽

Large Mining Height ◽

Mining Height

In the process of high-intensity and large-space mining in Shendong mining area, various surface cracks are generated on the surface, resulting in serious damage to the surface buildings and the local ecological environment. To study the influence of overlying rock movement on surface failure of near-field single key strata of near-shallow buried and large mining height working face, the relationship between overburden movement, strata pressure appearance, and surface failure at working face 52307 in Daliuta mining area was analyzed by field measurement and numerical simulation. The results show the following: (1) there is only one thick and hard key stratum in the overburden of large mining height and near-shallow buried working face. Under the condition of presplitting roof blasting, the first weighting step is still as high as 95 m, and the periodic breaking step of roof is 20–30 m. During the weighting, the working resistance of support is still close to the rated resistance. (2) The single key stratum plays an obvious role in controlling overburden movement. After the first weighting of the working face, a stepped subsidence crack appears on the surface within a short time, and the crack lags behind the working face for about 5 m. (3) During each periodic weighting process, the breaking and subsidence of key blocks are accompanied by surface cracks.

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