The Height and Scope of Overburden Fractured Zone of Thick Coal Seam Based on Different Gob Behavior for a Case Coal Mine in China

2019 ◽  
Vol 37 (4) ◽  
pp. 3299-3311 ◽  
Author(s):  
Chunlei Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Thick Coal Seam ◽  
Fractured Zone

scholarly journals Study on Roof-Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Yunpei Liang ◽  
Lei Li ◽  
Xuelong Li ◽  
Kequan Wang ◽  
Jinhua Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Research Work ◽  
Maximum Principal Stress ◽  
Complicated Structure ◽  
Mining Technology ◽  
Thick Coal Seam ◽  
Soft Coal ◽  
Mining Depth ◽  
Arch Forms

With mining technology and mechanization degree being improving, fully mechanized caving mining technology (FCM) has become a main method for thick coal seam extraction in China. However, roof-coal caving characteristics in turn restrict its recovery efficiency, especially for the coal seam with complicated structure (CCS), that is, the coal seam comprises hard or soft coal and gangue. In order to explore the key factors influencing the roof-coal caving and recovery characteristics, related research work has been conducted as follows: firstly, a mechanical model of CCS has been established, which indicates the strength of the coal and gangue will directly affect the roof-coal recovery. Meanwhile, based on the geological settings of Qinyuan coal mine, numerical simulation on roof-coal caving law under different thicknesses of hard or soft coal and gangue has been performed using UDEC software. The results show that the maximum principal stress will increase with the increase of mining depth, making the roof-coal to break easily. Furthermore, the range of the plastic zone of the top coal and the damage degree of the top coal increase with the increase of mining depth. Physical modeling results show that when an extraction-caving ratio is 1, the number of times the coal arch forms is 0.43 at every caving, up to a maximum of 3; the number of times coal arch forms with an extraction-caving ratio of 2 is 4.65 times larger than that with an extraction-caving ratio of 1. The probability of coal arch formation with an extraction-caving ratio of 3 is minimal, about 0.4, which is due to that the arch span is large and the curvature is small, so it is difficult to form a stable arch structure. According to the mechanical characteristics of roof-coal in Qinyuan coal mine, deep-hole blasting technique has been used to reduce the fragments of roof-coal crushed. The results show that this technique can effectively improve the recovery of roof-coal.

scholarly journals Determination of cyclic filling length in gob-side entry retained with roadside filling and its application

2020 ◽  
Author(s):  
Zizheng Zhang ◽  
Jianbiao Bai ◽  
Xianyang Yu ◽  
Weijian Yu ◽  
Min Deng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Difference Method ◽  
Suggested Method ◽  
Stress Difference ◽  
Thick Coal Seam ◽  
Mechanics Model ◽  
Working Face ◽  
Geological Conditions ◽  
The Relationship

Abstract Gob-side entry retained with roadside filling (GER-RF) plays a key role in achieving coal mining without pillar and improving the coal resource recovery rate. Since there are few reports on the cyclic filling length of GER-RF, a method based on the stress difference method is proposed to determine the cyclic filling length of GER-RF. Firstly, a stability analysis mechanics model of the immediate roof above roadside filling area in GER was established, then the relationship between the roof stress distribution and the unsupported roof length was obtained by the stress difference method. According to the roof stability above roadside filling area based on the relationship between the roof stress and its tensile strength, the maximum unsupported roof length and rational cyclic filling length of GER-RF. Combined with the geological conditions of the 1103 thin coal seam working face of Heilong Coal Mine and the geological conditions of the 1301 thick coal seam working face of Licun Coal Mine, this suggested method was applied to determine that the rational cyclic filling lengths of GER-RF were 2.4 m and 3.2 m, respectively. Field trial tests show that the suggested method can effectively control the surrounding rock deformation along with rational road-in support and roadside support, and improve the filling and construction speed.

A Coal Mine Hydraulic Support Design and Type Selection of Medium Thick Coal Seam

2014 ◽  
Vol 633-634 ◽  
pp. 1128-1132
Author(s):  
Li Rong Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Simulation Method ◽  
Bottom Plate ◽  
Mining Equipment ◽  
Hydraulic Support ◽  
Support Design ◽  
Thick Coal Seam ◽  
Technical Parameters ◽  
Selection Of

Design and selection of hydraulic support is the core of coal mine fully mechanized mining equipment selection and matching, determine the hydraulic supporting strength Using the numerical simulation method and shallow buried depth of roof structure of theoretical calculation method, determines the necessary technical parameters such as the support frame, the bracket height and the bottom plate pressure According to the coal seam thickness and coal seam structure, which has the instructive meaning in application.

scholarly journals Comprehensive Study of Strata Movement Behavior in Mining a Longwall Top Coal Caving Panel of a Composite Coal Seam with Partings

2020 ◽  
Vol 10 (15) ◽  
pp. 5311
Author(s):  
Hongtao Liu ◽  
Linfeng Guo ◽  
Guangming Cao ◽  
Xidong Zhao ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Coal Seam ◽  
Physical Modeling ◽  
Image Correlation ◽  
Thick Coal Seam ◽  
Fractured Zone ◽  
Strata Movement ◽  
Longwall Panel ◽  
Longwall Top Coal Caving ◽  
Comprehensive Study

Strata movement due to extraction of a longwall panel is of great significance both in terms of environment and ground control. Thick coal seam extraction is expected to severely disturb the overburden, which is critical. Most studies use only one or two methods to investigate strata movement that are not thorough or comprehensive. This paper presents a detailed comprehensive case study of strata movement in extraction of a longwall top coal caving panel of a composite coal seam with partings in the Baozigou Coal Mine. The caved zone and fractured zone development were captured through physical modeling by incorporating the digital image correlation method (DICM), universal distinct element code (UDEC) numerical modeling, and field observation with the method of high-pressure water injection. The result of the physical modeling is 90 m. The numerical modeling result is 84 m. Field data show that the fractured zone is 81 m. Therefore, it demonstrates that the results from different methods are consistent, which indicates that the results from this comprehensive study are reliable and scientific.

scholarly journals Formation Mechanism and the Height of the Water-Conducting Fractured Zone Induced by Middle Deep Coal Seam Mining in a Sandy Region: A Case Study from the Xiaobaodang Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaoshen Xie ◽  
Enke Hou ◽  
Shuangming Wang ◽  
Xueyang Sun ◽  
Pengfei Hou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Formation Mechanism ◽  
Coal Mine ◽  
Field Measurements ◽  
Development Stage ◽  
Mine Safety ◽  
Maximum Height ◽  
Fractured Zone ◽  
Seam Mining

The height of the water-conducting fractured zone (WCFZ) is a basic parameter related to water protection in coal mines and is also crucial for aquifer protection and mine safety. In order to accurately detect the height and shape and reveal the formation mechanism of the WCFZ, which is caused by middle-deep coal seam mining in a sandy region, the 112201 coalface at the 1# coal mine of Xiaobaodang was taken as a case study. Filed measurements including fluid leakage, borehole TV, and similar simulation were adopted to analyze the regularity of the WCFZ in this area. The detection results of field measurements showed that the maximum height of the WCFZ was 177.07 m in a borehole near the open-off cut, and the ratio of the height of the water-conducting fractured zone divided by the mining thickness was 30.53. The WCFZ acquired an inward-convergent saddle shape, which was inclined to the goaf. The saddle bridge was located at the boundary of the goaf, and the saddle ridge was located at the center of the goaf. Also, through analyzing the results of similar simulations, we found that, in the process of mining, separation cracks and the beam structure were the main forms of overburden disturbance transmitting upward and ahead of mining, respectively. The main cause of the increase in height of the WCFZ was the connection of the separation cracks and vertical cracks caused by fractures of beam structures. The development of the WCFZ was divided into five stages: incubation stage, development stage, rapidly increasing stage, slowly increasing stage, and stable stage. Moreover, the duration of each stage was related to the lithology and mining technology. This research can provide significant theoretical insights for the prediction of the WCFZ, enabling the prevention of water hazards on mine roofs and assisting with water resources protection.

Numerical Simulation and Analysis of Rock Burst Induced by Roof Movement

2014 ◽  
Vol 522-524 ◽  
pp. 1394-1398
Author(s):  
Tao Qin ◽  
Yong Li Liu ◽  
Chang Ji Dong ◽  
Ping Wang
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Coal Seam ◽  
Pressure Distribution ◽  
Coal Mine ◽  
Process Simulation ◽  
Hard Coal ◽  
Thick Coal Seam ◽  
Soft Coal ◽  
Mining Conditions

For composite thick seams have been incidents burst power disasters, and seriously affect the safety of the mine production.Based on the engineering background in coal mine, through the same mining conditions, stope mining process simulation which happens in single hard coal, soft coal and single composite thick Coal Seam of Island face were studied through comparative analysis by FLAC3D　numerical simulation technology. Tendency and trend of the pressure distribution results obtain through the comparative analysis . The research results has been applied in the actual coal mining.

scholarly journals Analysis on Influence Factors of Roadway Instability in High-Stress, Steeply Inclined Extra-Thick Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Hai Rong ◽  
Liting Pan ◽  
Xiaoyan Li ◽  
Ming Wang ◽  
Zeliang Qu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
High Stress ◽  
Support Effect ◽  
Theoretical Research ◽  
Thick Coal Seam ◽  
The North ◽  
Roof Fall ◽  
Roadway Support ◽  
Bolt Support

In order to solve the problem of roadway support safety in coal mining under high stress conditions and to improve safe and efficient production in coal mines, the control countermeasures of the surrounding rock stability and the optimization scheme of support are put forward and the model and numerical simulation of roadway bolt support system are established. Based on bolt support theory and instability mechanism of the coal rock dynamic system, this paper puts forward the evaluation of support effect and the optimization parameters of bolt support, and the scheme of mine pressure monitoring and the corresponding support optimization system are established. The roof fall accident and the bolt and cable of support have been broken in the Wudong coal mine, the phenomenon of bolt pulling out in the roadway. The causes of roof fall are analyzed and the solutions are put forth, judging the influence of different factors on roadway support. In view of the roof fall accident in the North Lane of the east wing of the +575 level 43 #coal seam in the north mining area of the Wudong coal mine, the cause analysis and support suggestions are made. And, according to the performance of the bolting material and anchoring agent, the laboratory theoretical research was carried out. Through the experiment, it is concluded that the FRP bolt with a diameter not less than 27 mm is the first choice for the side support of the working face in the mining roadway, then ribbed steel bolt with a diameter not less than 20 mm for the nonworking face, and the length of the anchor rod not less than the range of the loose circle. Therefore, full-length anchoring should be carried out in roadway support, the anchorage length of the anchor cable should be increased, and the integrity of the roof should be improved, so as to reduce the amount of roadway roof separation and improve the support effect.

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