Characterizing Coal Pillar Deformation and Air Leakage Pattern During Longwall Face Mining

Research on the Law of Coal Pillar Spontaneous Combustion and Fire Prevention and Control Technology

“…Such as three-phase foam as the representative of the foam class fire prevention materials, as well as the colloid as the representative of the colloid fire prevention materials gradually into the field of vision, the field application effect is remarkable. , Regarding research on coal pillars, most scholars at home and abroad focus on the mechanical characteristics and fragmentation mechanism of coal pillars. − However, it is worth noting that coal pillar cracks, under the influence of underground formation pressure, would further develop and result in a large number of air leakage channels. Besides, air circulation caused by the atmospheric pressure difference on both sides of coal pillars may also accelerate the spontaneous combustion of fragmented coal in coal pillars. , Under the guidance of safety-related coefficient criteria and safety principles, Tang divided the narrow coal pillar and the goaf into “safe zone”, “general zone”, and “dangerous zone”, according to two indicators, i.e., the permeability of the narrow coal pillar and the spontaneous combustion risk of residual coal in the goaf . Teng adopted FLAC 3D numerical simulation software to simulate the dynamic evolution characteristics of stress and displacement in the upper coal pillar.…”

“…Besides, air circulation caused by the atmospheric pressure difference on both sides of coal pillars may also accelerate the spontaneous combustion of fragmented coal in coal pillars. 20 , 21 Under the guidance of safety-related coefficient criteria and safety principles, Tang divided the narrow coal pillar and the goaf into “safe zone”, “general zone”, and “dangerous zone”, according to two indicators, i.e., the permeability of the narrow coal pillar and the spontaneous combustion risk of residual coal in the goaf. 22 Teng adopted FLAC 3D numerical simulation software to simulate the dynamic evolution characteristics of stress and displacement in the upper coal pillar.…”

Coevolution mechanism and branch of pillar‐overburden fissures in shallow coal seam mining

“…At the same time, the generation of overburden fractures leads to an increase in the activation rate of the overburden‐bearing structure and a change in the initial stable load, which reacts on the coal pillar to form a cyclic space‐time evolution system 16,17 . A shallow coal seam typically has thin bearing strata and a thick load layer, which promotes the formation of permanent fissure channels on both sides of the working face between coal pillars at a certain angle and penetrating the surface; this results in hidden disasters such as air leakage, water inrush, and sand inrush in the working face 18,19 . Due to the supporting role of coal pillars, uneven surface settlement often results, and the stepped subsidence of the surface is caused.…”

“…16,17 A shallow coal seam typically has thin bearing strata and a thick load layer, which promotes the formation of permanent fissure channels on both sides of the working face between coal pillars at a certain angle and penetrating the surface; this results in hidden disasters such as air leakage, water inrush, and sand inrush in the working face. 18,19 Due to the supporting role of coal pillars, uneven surface settlement often results, and the stepped subsidence of the surface is caused. Concurrently, O-X breakage and collapse of the working face with the coal pillar as the boundary lead to the stress concentration phenomenon of a triangular area of the working face.…”