The Influence of Overburden Structure on Mine Ground Pressure Appearance in Working Face with Super-large Mining Height: a Case Study in Shendong Mining Area

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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Research on Overburden Movement Characteristics of Large Mining Height Working Face in Shallow Buried Thin Bedrock

Energies ◽

10.3390/en12214208 ◽

2019 ◽

Vol 12 (21) ◽

pp. 4208 ◽

Cited By ~ 7

Author(s):

Qingxiang Huang ◽

Yanpeng He

Keyword(s):

Physical Simulation ◽

Mining Area ◽

Engineering Problem ◽

Dynamic Crack ◽

Working Face ◽

Time Space ◽

Movement Distance ◽

Large Mining Height ◽

Thin Bedrock ◽

Mining Height

The overburden movement of the large mining height working face of shallow buried thin bedrock (SBTB) is a complex engineering problem with “time-space-intension”, which is of great significance to realize efficient and safe mining in the northern Shaanxi mining area. Based on the research object of No. 22201 working face in Zhangjiamao Coal Mine, the roof structure characteristics of large mining height working face in SBTB are researched by field drilling measurement, laboratory test, physical and numerical simulation. The results show that: (1) Based on the measured data of the drillholes, it is concluded that under the mining conditions of SBTB with large mining height, the roof movement is ahead of the weighting of the working face, and the working resistance has a significant time effect. The advanced movement distance is about 20 m, which can be used as an early warning index of the weighting. The lag movement distance in the roof with horizon of 30 m is two periodic weighting intervals, which are about 26 m. (2) The first weighting interval of the working face is 32 m. The roof first break has obvious step sinking phenomenon, and the measured surface appears at a position 45 m away from the transport slot. It is statistically concluded that the periodic weighting interval is 9.5~16.5 m, the average weighting interval is 13 m, which is equivalent to the periodic dynamic crack spacing of the surface. (3) The results of field measurement and physical simulation show that the breaking angle of the roof of the No. 22201 large mining height is about 66°, and the periodic stepping distance of the T-junction suspension area is 6~8m. Along the strike of the working face, the roof breaking is mainly arc arched. The research results ensure the safe and green mining of shallow coal seam.

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The Three-Dimensional Similar Simulation of Stress Regular Pattern of Roof of Large Mining Height

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.945-949.1190 ◽

2014 ◽

Vol 945-949 ◽

pp. 1190-1195 ◽

Cited By ~ 1

Author(s):

Xiao Tao Zeng ◽

Ning Wang ◽

Cong Jiang ◽

Yun Yi Zhang ◽

Gang Chen

Keyword(s):

Three Dimensional ◽

Mining Area ◽

In Situ Stress ◽

Stimulation Test ◽

Mine Pressure ◽

Pressure Behavior ◽

Working Face ◽

Large Mining Height ◽

Roadway Deformation ◽

Mining Height

Based on the distribution of in-situ stress and the special conditions of the large mining height in one mining area, the author conducted the analogy stimulation test of the mine pressure behavior and the roadway deformation law. This research, mainly based on the geographical conditions of 1 to 2 coal seam of this mining area, stimulated the mine pressure behavior of the working face and the roadways, as the mining height is 5meters and 6meters. Through this analogy stimulation test, the mine pressure behavior of working face, in the mining process with large mining height, is analyzed and summarized.

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Study on Rational Width of Entry Protection Coal-Pillar in Large Mining Height Working Face

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.413.404 ◽

2011 ◽

Vol 413 ◽

pp. 404-409

Author(s):

Xu Feng Wang ◽

Dong Sheng Zhang ◽

Ting Feng Cui ◽

Jin Liang Wang ◽

Wei Zhang

Keyword(s):

Numerical Simulation ◽

Theoretical Calculation ◽

Coal Pillar ◽

Engineering Practice ◽

Pillar Width ◽

Pillar Design ◽

Working Face ◽

Large Mining Height ◽

Mining Height

This paper demonstrates the attempt to identify a reasonable chain pillar width in the condition of large mining height, along with a case study at the gateway of No.1103 panel with large mining height in Suancigou Mine. Theoretical calculation and numerical simulation were employed as the main approaches during the research to figure out the rational width of entry protection coal-pillar, which was then proved to be capable for engineering practice. The results that derived from our research can offer technical support for spot production, and serve as references for future investigation upon chain pillar design under large mining height.

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Case Study on the Mechanism of Influence of Stoppage on Ground Pressure under Different Rates of Advance

Advances in Civil Engineering ◽

10.1155/2021/5574693 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Xiaoxu Gao ◽

Xinyu Shi ◽

Weibin Guo

Keyword(s):

Load Transfer ◽

Mining Area ◽

Ground Pressure ◽

Working Face ◽

Force Majeure ◽

Rate Of Increase ◽

Coal Wall ◽

Two Stages ◽

Roof Falling

Because of daily maintenance, equipment damage, gas overrun, and other force majeure factors, the continuous stopping of the working face causes the roof pressure to accumulate, which leads to causing accidents such as coal wall spalling and roof falling. To address the roof safety problem caused by continuous stoppages, the 620 working face in the Huangling mining area is taken as the research object. Through field measurement, theoretical analysis, numerical simulation, and other research methods, the influence and mechanism of stopping pressure under different rates of advance are studied. The results show that the velocity factor of roof load transfer is positively correlated with the advancing velocity of the working face; the reasonable length of the suspended roof is mainly affected by the number of caving holes and the effect of pressure relief; and comparing the two stages of advance speed of 4.8 m/d and 12.8 m/d, the periodic weighting step distance of the latter increases by 24.4% compared with the former, and the rate of increase of support load caused by stopping mining increases by 42.1% compared with the former. The roof pressure accumulation caused by stopping mining is increased. Taking appropriate measures for local forced caving of the working face can release the roof pressure and reduce the risk of local caving of the working face. The study can provide a theoretical basis for roof control of continuous stopping under similar engineering conditions.

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Study on Fracture and Stress Evolution Characteristics of Ultra-Thick Hard Sandstone Roof in the Fully Mechanized Mining Face with Large Mining Height: A Case Study of Xiaojihan Coal Mine in Western China

Advances in Civil Engineering ◽

10.1155/2018/5474165 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 3

Author(s):

Feng Ju ◽

Meng Xiao ◽

Zequan He ◽

Pai Ning ◽

Peng Huang

Keyword(s):

High Strength ◽

Western China ◽

Stress Evolution ◽

Working Face ◽

Mining Condition ◽

Evolution Characteristics ◽

Large Mining Height ◽

Evolution Laws ◽

Mining Face ◽

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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Numerical Analysis on Ground Pressure Feature in Fully Mechanized Coal Face

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.807-809.2299 ◽

2013 ◽

Vol 807-809 ◽

pp. 2299-2303

Author(s):

Wei Jian Yu ◽

Tao Feng ◽

Gang Ye Guo

Keyword(s):

Numerical Analysis ◽

Abutment Pressure ◽

Numerical Procedure ◽

Wall Rock ◽

Coal Face ◽

Distribution Form ◽

Ground Pressure ◽

Working Face ◽

Set Up ◽

Mining Height

Base on the fully mechanized coal face of 8113 (1) in LaoYingSan mine, numerical analysis method was applied to analyze the ground pressure feature, FLAC software is carried out to set up numerical model, and offer numerical procedure. The mining abutment pressure distribute form and its partition in front of fully mechanized working face. All four different mining height (2.6m2.8m3.0m3.2m) was respectively calculated. In addition, the influence of mining speed to mining abutment pressure and intervals is analyzed, four different mining distance (20m30m40m50m) selected separately. Afterwards, the different solution analyzed respectively, these results show that the mining abutment pressure distribution form in front of fully mechanized working face essentially identical, they including the stress increasing zones, the stress decreasing zones and the initial rock stress stable field. The influence of mining pace to wall rock looseness range greater than mining height.

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Mining-Induced Stress Control by Advanced Hydraulic Fracking under a Thick Hard Roof for Top Coal Caving Method: A Case Study in the Shendong Mining Area, China

Minerals ◽

10.3390/min11121405 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1405

Author(s):

Kaige Zheng ◽

Yu Liu ◽

Tong Zhang ◽

Jingzhong Zhu

Keyword(s):

Stress Transfer ◽

Mining Area ◽

Fracture Networks ◽

Horizontal Fracture ◽

Hard Roof ◽

Working Face ◽

Huge Impact ◽

Mining Pressure ◽

Impact Kinetic Energy ◽

Mining Height

Fully mechanized top-coal caving mining with high mining height, hard roofs and strong mining pressure are popular in the Shendong mining area, China. The occurrence of dynamic disasters, such as rock burst, coal and gas outburst, mine earthquakes and goaf hurricanes during the coal exploitation process under hard roof conditions, pose a threat to the safe production of mines. In this study, the characteristics of overburden fracture in fully mechanized top-coal caving with a hard roof and high mining height are studied, and the technology of advanced weakening by hard roof staged fracturing was proposed. The results show that the hard roof strata collapse in the form of large “cantilever beams”, and it is easy to release huge impact kinetic energy, forming impact disasters. After the implementation of advanced hydraulic fracturing, the periodic weighting length decreases by 32.16%, and the length of overhang is reasonably and effectively controlled. Ellipsoidal fracture networks in the mining direction of the vertical working face, horizontal fracture networks perpendicular to the direction of the working face, and near-linear fracture planes dominated by vertical fractures were observed, with the accumulated energy greatly reduced. The effectiveness of innovation technology is validated, and stress transfer, dissipation and dynamic roof disasters were effectively controlled.

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