Abstract
The development law of mining cracks in shallow coal seams under gully topography was used as the research base to analyze the development characteristics of mining cracks in the 5-2 coal mining face of Anshan Coal Mine, and the weak strength was established. The basic top force model under the action of the overburden is the “nonuniformly distributed load beam” structure model. Through similar simulation research and theoretical calculation analysis, the fracture development law of the working face passing through the valley is studied. Based on the mechanical analysis of the beam structure with nonuniform load, the discriminant conditions of the stability of the bearing structure of the bedrock are derived, the calculation formulas of the parameters such as the pressure, shear force, and the ultimate span of the basic roof at both ends are determined, the influence law of the thickness and slope change of the weak strength overburden on the mining crack spacing is revealed, and the influence of the slope of the weak strength overburden on the weighting step distance on the beam with nonuniform load is obtained. The phenomenon is that the burial depth has a great influence on the step distance of weighting. The practice shows that the distance between the mining-induced fractures determined by the nonuniformly distributed load beam model and the periodic weighting step, the height of fracture development, and the buried depth are approximately the same; the mining-induced fractures in the overburden develop and evolve periodically with the failure and instability of the bedrock. The research results will clarify the development mechanism of surface cracks in the gully mining area, which is of great significance to reduce terrain disasters.
Highlights
E development law of mining cracks in shallow coal seams under gully topography was used as the research base to analyze the development characteristics of mining cracks in the 5-2 coal mining face of Anshan Coal Mine, and the weak strength was established. e basic top force model under the action of the overburden is the “nonuniformly distributed load beam” structure model. rough similar simulation research and theoretical calculation analysis, the fracture development law of the working face passing through the valley is studied
The coal seam is buried shallowly, only dozens of meters away from the surface, and thin bedrock outcropping is common. e bedrock is covered by thick Quaternary loess and Neogene laterite
Since the 1990s, with the expansion of the mining of shallow-buried coal seams, in-depth studies have been conducted on the instability characteristics of overlying strata failure and the development law of fracture
Summary
Anshan minefield is in a typical loess ridge landform. e lowest elevation is 1075.9 m, and the highest elevation is 1364.5 m, with a large drop. E lowest elevation is 1075.9 m, and the highest elevation is 1364.5 m, with a large drop. In this region, there are many gullies with the buried depth of coal seam about 20∼70 m. The coal seam is +1165 m, and the ground elevation is +1191∼+1304 m. It is located in the north side of Shasongliang and the northwest side of Caigou. E direct roof is fine-grained sandstone with an average thickness of 1.12 m. E basic roof is a silty, fine-grained sandstone with an average thickness of 12 m, and the bedrock is covered by a sandy soil layer According to the drilling data and outcrop information, the lithology of the roof is generally stable. e average thickness of the pseudo-roof is 0.2 m, and it is carbonaceous shale. e direct roof is fine-grained sandstone with an average thickness of 1.12 m. e basic roof is a silty, fine-grained sandstone with an average thickness of 12 m, and the bedrock is covered by a sandy soil layer
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