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Theoretical and Experimental Investigation on Top Coal Drawing Mechanism Considering Overburden Pressures in Longwall Top-coal Caving
https://orcid.org/http://orcid.org/0000-0001-8086-1027
Longwall top coal caving (LTCC) mining technique is widely used in thick and extra-thick coal seams in China, India and Türkiye. Considering that the depth of coal seam varies widely (from 188 to 988 m in China), the different overburden pressure has great influence on the failure and drawing process of top coal in LTCC. In this paper, the top coal drawing mechanism considering overburden pressures was investigated through theoretical analysis, physical experiments and numerical calculation. The shape of the drawing body, coal–rock interface and recovery of top coal under different overburden pressure were analyzed deeply. The results show that the motion acceleration and fluidity of top coal particles increase first and then decrease with the increase of overburden pressure. When gangue-to-coal density ratio (γ) is larger than 1, the increasing of overburden pressure is beneficial to the recovery of top coal to some extent. With the increase of overburden pressure, the top coal boundary in the initial drawing stage gradually expands to the goaf, which increases the volume of the initial drawing body. The expansion of the initial drawing body’s width is attributed to the growth of the goaf-side width and is unrelated to the support-side width. With the increasing of the overburden pressure, the proportion of strong force chain gradually increases and the force arch is gradually formed between the goaf and the coal wall, which is conductive to the mixing of gangue form the goaf direction. This is the internal reason why the top coal recovery ratio decreases when the overburden pressure is too large. The “excessive coal drawing method” is proposed for deeply buried coal seams, which is conducive to recover more top coal and reduce the residual coal left in the goaf.
Effect of overburden pressures on the top coal drawing mechanisms were revealed and verified by experimental results.
With the increase of overburden pressure, the coal–rock interface gradually expands to the goaf side, which increases the volume of the drawing body.
The strong force chain arch will form between the goaf and the coal wall when overburden pressure is large, which resulting in the early mixing of gangue form the goaf side.
Theoretical and Experimental Investigation on Top Coal Drawing Mechanism Considering Overburden Pressures in Longwall Top-coal Caving
https://orcid.org/http://orcid.org/0000-0001-8086-1027
Longwall top coal caving (LTCC) mining technique is widely used in thick and extra-thick coal seams in China, India and Türkiye. Considering that the depth of coal seam varies widely (from 188 to 988 m in China), the different overburden pressure has great influence on the failure and drawing process of top coal in LTCC. In this paper, the top coal drawing mechanism considering overburden pressures was investigated through theoretical analysis, physical experiments and numerical calculation. The shape of the drawing body, coal–rock interface and recovery of top coal under different overburden pressure were analyzed deeply. The results show that the motion acceleration and fluidity of top coal particles increase first and then decrease with the increase of overburden pressure. When gangue-to-coal density ratio (γ) is larger than 1, the increasing of overburden pressure is beneficial to the recovery of top coal to some extent. With the increase of overburden pressure, the top coal boundary in the initial drawing stage gradually expands to the goaf, which increases the volume of the initial drawing body. The expansion of the initial drawing body’s width is attributed to the growth of the goaf-side width and is unrelated to the support-side width. With the increasing of the overburden pressure, the proportion of strong force chain gradually increases and the force arch is gradually formed between the goaf and the coal wall, which is conductive to the mixing of gangue form the goaf direction. This is the internal reason why the top coal recovery ratio decreases when the overburden pressure is too large. The “excessive coal drawing method” is proposed for deeply buried coal seams, which is conducive to recover more top coal and reduce the residual coal left in the goaf.
Effect of overburden pressures on the top coal drawing mechanisms were revealed and verified by experimental results.
With the increase of overburden pressure, the coal–rock interface gradually expands to the goaf side, which increases the volume of the drawing body.
The strong force chain arch will form between the goaf and the coal wall when overburden pressure is large, which resulting in the early mixing of gangue form the goaf side.
Theoretical and Experimental Investigation on Top Coal Drawing Mechanism Considering Overburden Pressures in Longwall Top-coal Caving
https://orcid.org/http://orcid.org/0000-0001-8086-1027
Longwall top coal caving (LTCC) mining technique is widely used in thick and extra-thick coal seams in China, India and Türkiye. Considering that the depth of coal seam varies widely (from 188 to 988 m in China), the different overburden pressure has great influence on the failure and drawing process of top coal in LTCC. In this paper, the top coal drawing mechanism considering overburden pressures was investigated through theoretical analysis, physical experiments and numerical calculation. The shape of the drawing body, coal–rock interface and recovery of top coal under different overburden pressure were analyzed deeply. The results show that the motion acceleration and fluidity of top coal particles increase first and then decrease with the increase of overburden pressure. When gangue-to-coal density ratio (γ) is larger than 1, the increasing of overburden pressure is beneficial to the recovery of top coal to some extent. With the increase of overburden pressure, the top coal boundary in the initial drawing stage gradually expands to the goaf, which increases the volume of the initial drawing body. The expansion of the initial drawing body’s width is attributed to the growth of the goaf-side width and is unrelated to the support-side width. With the increasing of the overburden pressure, the proportion of strong force chain gradually increases and the force arch is gradually formed between the goaf and the coal wall, which is conductive to the mixing of gangue form the goaf direction. This is the internal reason why the top coal recovery ratio decreases when the overburden pressure is too large. The “excessive coal drawing method” is proposed for deeply buried coal seams, which is conducive to recover more top coal and reduce the residual coal left in the goaf.
Effect of overburden pressures on the top coal drawing mechanisms were revealed and verified by experimental results.
With the increase of overburden pressure, the coal–rock interface gradually expands to the goaf side, which increases the volume of the drawing body.
The strong force chain arch will form between the goaf and the coal wall when overburden pressure is large, which resulting in the early mixing of gangue form the goaf side.
Theoretical and Experimental Investigation on Top Coal Drawing Mechanism Considering Overburden Pressures in Longwall Top-coal Caving
Rock Mech Rock Eng
Zhang, Jinwang (Autor:in) / Zhang, Yipeng (Autor:in) / Yang, Shengli (Autor:in) / Cheng, Dongliang (Autor:in) / Wei, Weijie (Autor:in) / Yang, Liu (Autor:in)
Rock Mechanics and Rock Engineering ; 58 ; 2901-2927
01.03.2025
27 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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