Experimental and numerical investigation on coal drawing from thick steep seam with longwall top coal caving mining

Zhang, Jinwang; Wang, Jiachen; Wei, Weijie; Yi, Chul-Young; Song, Zhengyang

doi:10.1007/s12517-018-3421-x

Cited by 40 publications

(20 citation statements)

References 16 publications

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“…e rock principal stresses obtained from equations (6)-(8) are as follows: Figure 4: e fitting curves of each factor and F w . 6 Advances in Civil Engineering…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

“…Restrained by the top-coal caving property (TCCP) and the recovery rate, the coal seam thickness in the fully mechanized mining with top-coal caving technology (FMMTCCT) is less than 14 m [4]. Considering the complicated mining technology and low recovery rate, the slice mining cannot suit the extremely thick coal seam [5][6][7]; thus, the fully mechanized caving mining with large mining height (FMCMLMH) is gradually becoming the main mining technology. Utilizing ground pressure to break the top coal, the power source and the mechanical mechanism of top-coal caving and rib spalling are all the same.…”

Section: Introductionmentioning

confidence: 99%

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Cutting-Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

Wang

Zhao

Yetilmezsoy

et al. 2019

Advances in Civil Engineering

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Serious rib spalling and low recovery rate problems caused by the poor top-coal caving property (TCCP) were investigated in fully mechanized caving mining with large mining height (FMCMLMH) of extremely thick coal seam. For this aim, theoretical calculation, numerical simulation, and engineering application were applied to study the reasonable cutting-caving ratio under the influence of different factors. The calculation formula of reasonable cutting height in FMCMLMH was obtained, and effective factors were determined. Moreover, Ft (the top-coal yield failure coefficient) and Fw (the coal wall yield failure coefficient) were defined, and each factor was fitted by using a linear regression equation. The minimum Ft of fully fractured top coal was 0.6, and the main influencing factors were buried depth and Protodyakonov coefficient. The maximum Fw of the stable coal wall was 1.5, and the main influencing factors were buried depth and cutting height. According to the relationship between coal wall stability and recovery rate, the relationship between coal seam strength and top-coal thickness at different cutting heights was obtained, and the mining zone was divided into four subzones. Engineering application showed that the optimal cutting height of Xiegou Coal Mine was 4 m, the cutting-caving ratio was 1 : 2.75, and the recovery rate could reach more than 85%, which was the most reasonable.

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“…e rock principal stresses obtained from equations (6)-(8) are as follows: Figure 4: e fitting curves of each factor and F w . 6 Advances in Civil Engineering…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cutting-Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

Wang

Zhao

Yetilmezsoy

et al. 2019

Advances in Civil Engineering

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“…Thus, ground control problems, such as roof falls, bumps, and outbursts, are minimized and operation costs should be lower. Tangshan, Huafeng, and Dayuan coal mines, among others, are using the technology for deep inclined thick coal seams [31][32][33].…”

Section: Pressure and Convergence In Gateroads Of The 18111-1 Panelmentioning

confidence: 99%

A New Gob-Side Entry Layout for Longwall Top Coal Caving

2018

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In China, gob-side entry is typically located one pillar-width (less than 5 m) away from the previously mined-out panel in a conventional longwall panel using top coal caving (LTCC). Design of gob-side entries is a challenge due to the complex dynamic loading process during their service life. A new gob-side entry (NGE) design practice is presented here for Zhenchengdi Colliery, which has many advantages. A theoretical analysis is presented followed by numerical modeling. The modeling included the double-yield constitutive model for gob behavior to analyze the stress environment for the gob-side entry with validation through field observations. The results indicate that pre-mining stress within gob occurred 51 m away from the gob edge. The NGE is located within a destressed zone in the entire panel system, which results in lower side abutment pressure for the adjacent panel to be mined. The stress concentration around the gob edge near the gob-side entry is relatively low (less than 0.1) compared with the other side of the gob. Field observations indicate that: (1) a simple support design, i.e., steel sets with wire mesh on the top, can maintain ground control and ventilation during active mining; (2) the periodic weighting interval is 9-12 m; (3) the length of the block "B" which "protects" the gob-side entry is 10-13 m; (4) stress distribution formula for the elevating section is derived; and (5) the roof pressure of the gob-side entry is much smaller than non-gob side entry and is smaller than the pre-mining stress. Deformation data of the gob-side entry shows that both roof-to-floor and rib-to-rib convergences are smaller than for the non-gob-side entry with an improved overall stress environment. Theoretical analysis, numerical modeling, and field observation are consistent, which validates the scientific foundations of the new technology.

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“…Zhu et al [9] analyzed overburden movement characteristics of top-coal caving mining in multiseam areas. Zhang et al [10] investigated the coal drawing from thick steep seam with longwall top-coal caving mining by experimental methods.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study of Rock Stratum Movement Characteristics in Longwall Mining

Liu

2019

Shock and Vibration

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The roof fracture is the main cause of coal mine roof accidents. To analyze the law of movement and caving of the roof rock stratum, the roof subsidence displacement, rock stratum stress, and the rock stratum movement law were analyzed by using the methods of the particle discrete element and similar material simulation test. The results show that (1) as the working face advances, regular movement and subsidence appears in the roof rock strata, and the roof subsidence curve forms a typical “U” shape. As the coal seam continues to advance, the maximum subsidence displacement remains basically constant, and the subsidence displacement curves present an asymmetric flat-bottomed distribution. (2) After the coal seam is mined, the overburden forms an arched shape force chain, and the arched strong chain is the path of the overburden transmission force. The farther away from the coal seam, the smaller the stress concentration coefficient is, but it is still in a high stress area, and the stress concentration position moves toward the middle area of the goaf. The stress concentration in front of the coal wall is the source of force that forms the abutment pressure. (3) Above the coal wall towards the goaf, a stepped fracture was formed in the roof rock stratum. The periodic fracture of the rock stratum is the main cause of the periodic weighting of the working face. Understanding the laws of rock movement and stress distribution is of great significance for guiding engineering practice and preventing the roof accidents.

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Experimental and numerical investigation on coal drawing from thick steep seam with longwall top coal caving mining

Cited by 40 publications

References 16 publications

Cutting-Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

Cutting-Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

A New Gob-Side Entry Layout for Longwall Top Coal Caving

Experimental and Numerical Study of Rock Stratum Movement Characteristics in Longwall Mining

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