Finite element modeling of stress distributions and problems for multi-slice longwall mining in Bangladesh, with special reference to the Barapukuria coal mine

A Novel Caving Model of Overburden Strata Movement Induced by Coal Mining

“…Undoubtedly, the lowest part of the strata above the mine level experiences the most severe fracturing with fracture initiation in shear from the wings of the excavation, creating numerous upward propagating fractures [4,15], whereas the shallow strata suffer from a certain amount of tensional stresses, leading to shear deformation and surface tensional cracks [5]. As the shields (hydraulic supports) move, the mine roof behind them continues to cantilever and caves into the mine void, which experiences the process of elastic deformation, plastic deformation, and failure [16,20], producing two types of tensile fractures at the surface over the panel: static tensile fracture above the side of a panel and dynamic tensile fractures that follow behind the advancing face [16,17].…”

“…Among these methods, longwall mining has the characteristics of safety, high efficiency, and high yield and is the preferred method of underground coal extraction. As can be seen in Figure 1, the process of mining involves the total exploitation of large, rectangular panels of coal several kilometers long and hundreds of kilometers wide, leaving only a movable hydraulic support behind to support the roof strata and further leading to land and strata subsidence and the hydro-geomechanical response of the long and hundreds of kilometers wide, leaving only a movable hydraulic support behind to support the roof strata and further leading to land and strata subsidence and the hydro-geomechanical response of the overlying aquifers [4,5,15]. The redistribution of the overburden stress regime caused by longwall mining brings about general increases in fracture porosity and permeability owing to the development of fractures, joints, and bedding separations, resulting in the disruption of the natural groundwater flow system to a great extent [12,15,16,44].…”

“…As can be seen in Figure 1, the process of mining involves the total exploitation of large, rectangular panels of coal several kilometers long and hundreds of kilometers wide, leaving only a movable hydraulic support behind to support the roof strata and further leading to land and strata subsidence and the hydro-geomechanical response of the long and hundreds of kilometers wide, leaving only a movable hydraulic support behind to support the roof strata and further leading to land and strata subsidence and the hydro-geomechanical response of the overlying aquifers [4,5,15]. The redistribution of the overburden stress regime caused by longwall mining brings about general increases in fracture porosity and permeability owing to the development of fractures, joints, and bedding separations, resulting in the disruption of the natural groundwater flow system to a great extent [12,15,16,44]. Currently, a variety of methods, ranging from analytical methods and field experiments to numerical and physical simulation, have been used that mainly focus on the mining-induced effects on the movement of overburden strata, the generation of fractures, and subsidence [2,13,29,30,[45][46][47].…”

“…Severe conflicts of interest are especially noteworthy regarding human life and the exploitation of energy resources [12][13][14][15][16][17][18][19][20][21][22][23][24]. Exploitation activities inevitably cause ground subsidence, water loss, building damage, and a series of other problems, especially in some eco-environmental fragile areas [3,[25][26][27][28][29][30][31][32][33][34][35].…”

Mining induced strata movement and roof behavior in underground coal mine

“…Poor knowledge of the characteristics of strata movement due to longwall mining can create very serious ground hazards, potentially jeopardizing the safety and lives of mine personnel, as well as affecting the productivity and efficiency of a mining operation. For decades, extensive effort has been paid to study the strata movement and stress distribution law induced by mining excavation and obtain comprehensive understanding of the permeability evolution of coal seam (Chen et al 2014;Xie et al 2015;Yang et al 2011a, b) and a proper design of a coal pillar (Chugh et al 1990;Hammy and Fejes 1992;Holla 1997;Holla and Buizen 1991a;Islam et al 2009). Holla and Buizen (1991b) performed an empirical study of the sub-surface deformation caused by retreating longwall mining and monitored the strata movement over a longwall panel and indicated that the three-joint-arch structure formed by the broken key roof stratum is monotonically unstable structure and its limit value is determined by the breaking convergence value.…”