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.

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 Occurrence Mechanism of Roof-Fall Accidents in Large-Section Coal Seam Roadways and Related Support Design for Bayangaole Coal Mine, China

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Shitan Gu ◽  
Bangyou Jiang ◽  
Gensheng Wang ◽  
Huabin Dai ◽  
Mingpeng Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Large Scale ◽  
Control Method ◽  
Tensile Failure ◽  
Large Section ◽  
Support Design ◽  
Roof Fall ◽  
Occurrence Mechanism ◽  
Fall Accidents

This study focused on large-scale roof-fall accidents occurred in large-section coal seam roadways of Bayangaole Coal Mine, Inner Mongolia, China, and investigated the occurrence mechanism of roof-fall and the related supporting control method in detail. Firstly, the fracture characteristics of the surrounding rocks on the roadway roof were measured using a stratum detector. The results showed that the roadway roof underwent the most severe failure with a maximum deformation of 3.53 m; the bedding separation and fracture zones were distributed at irregular intervals. Accordingly, the entire stratum was separated into several thin sublayers, significantly reducing the stability of roof. In addition, the roof medium grained sandstone of roadway is water-rich strata, and water aggravates the damage of roof. Next, the mechanism of the occurrence of roof-fall accidents in the roadway was elucidated in detail. The following three reasons are mainly attributed to the occurrence of roof-fall accidents: (i) effects of mining-induced stress and tectonic stress, (ii) existence of equipment cavern on the side of roadway, and (iii) unreasonable support parameters. On that basis, a new supporting design is proposed, including a more reasonable arrangement of anchor cables and bolts, bolts with full-length anchorage which are applicable in cracked and water-rich roadway, high-strength anchor cables, and crisscrossed steel bands. Moreover, high pretightening force was applied. Finally, a field test was performed, and the mining-induced roof displacement and stress on anchor cable (bolt) were monitored in the test section. The maximum roof displacements at the two monitoring sections were 143 mm and 204 mm, respectively, far smaller than the roadway’s allowable deformation. Moreover, the stress on roof anchor cables (bolts) was normal, and no anchorage-dragging and tensile failure phenomena were observed. The monitoring data indicated that the new supporting design was remarkable on the control of large-section coal seam roadway roof deformation.

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.

Numerical Simulation Analysis of Different Coal Mine Roadway Support Effect

2013 ◽  
Vol 807-809 ◽  
pp. 2356-2360 ◽  
Author(s):  
Guang Yi Sun ◽  
Xiao Luo
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Simulation Analysis ◽  
Support Effect ◽  
Surrounding Rock ◽  
Anchor Cable ◽  
Mine Roadway ◽  
Coal Wall ◽  
Roadway Support

The application of FLAC2D software long ditch coal mine extraction tunnel without support boltgrouting. Anchor when the anchor rope supporting and strengthening supporting state ofroadwaywere simulated and analyzed the change of roadway surrounding rock under differentsupport forms. Demonstrated the possibility that the current anchor cable anchor supporting andanalysis under the condition of the coal wall broken grouting bolt is the necessity of reinforcement.

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 Study on the Failure Characteristics of Coal Wall Spalling in Thick Coal Seam with Gangue

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Guosheng Li ◽  
Zhenhua Li ◽  
Feng Du ◽  
Zhengzheng Cao
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Internal Stress ◽  
External Stress ◽  
Theoretical Research ◽  
Risk Area ◽  
Thick Coal Seam ◽  
Failure Characteristics ◽  
Coal Wall ◽  
Stress Environment

Coal wall spalling is one of the main factors restricting the safe and efficient mining of thick coal seam, and the gangue has an important impact on the coal wall spalling. To obtain the failure characteristics of coal wall spalling in thick coal seam containing gangue, numerical calculation and theoretical research were used to analyze the morphological differences of coal wall spalling with different gangue positions. Besides, the damage depth, width, and stress environment of coal wall panel caused by the position of gangue were mainly studied, and the failure mechanics model of coal seam containing gangue was established by using the stability theory of pressure bar. The results show that, compared with coal wall spalling in coal seam without gangue, coal seam with the lower and middle gangue has a significant weakening effect on the wall spalling, and coal seam with the upper gangue has little effect on the wall spalling. In the case of coal seam with gangue, the upper gangue has the highest risk area of coal wall spalling with the maximum depth and width of 2.0 m and 2.3 m. For coal seam with the upper gangue, the dangerous areas of coal wall spalling are mainly distributed in the vicinity of the gangue; for coal seam without the gangue, they are mainly distributed in the middle of the coal seam. The gangue cannot change the law of the external stress distribution of the coal seam, but it has an obvious impact on the internal stress distribution of the coal seam. With the different positions of the gangue, the stress distribution in the coal seam has a great difference, and the maximum difference is 1.8 MPa. This shows that the stress environment of the coal seam containing gangue has the following typical characteristics: “the external stress is controlled by the overburden fracture, and the internal stress environment is controlled by the gangue.” Through the mechanical analysis of the coal seam containing gangue, it is further verified that the coal seam containing gangue is more prone to spalling at the position of gangue.

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