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Under the mining condition of extrathick coal seam, the overburden moves violently, the surface is destroyed seriously, and the discontinuous deformation such as cracks is fully developed. Taking Datong mining area as an example, this paper studies and analyzes the development characteristics and generation mechanism of surface cracks in loose laye...
Citations
... In the process of overburden collapse (Wang et al. 2019), the "key layer" plays a crucial role in influencing the height of the collapse, and the fissure development was slowed down to the subcritical layer, then the longitudinal fracture development was slowed down, and the fissure network developed horizontally (Dawei et al. 2019). The mining fissures show the distribution of the "O"-ring (Qin and Xu 2018;Yan et al. 2021). Through two-and three-dimensional physical similarity simulation, it is found that there is an interaction between overburden pressure unloading, permeability distribution, and gas dynamic migration. ...
In the increasingly intense high-intensity mining process of coal mines, many factors comprehensively influence the spatial distribution characteristics of overburden fissure. The characteristics of overburden fissure distribution have important guiding significance for gas control in mining. Explored the distribution characteristics of overburden fissure networks and the boundary characteristics of gas channels under multi-factor mining conditions (mining height, advancing speed, coal seam dip angle) through conducting two-dimensional physical similarity simulation experiments. Simultaneously analysed the changing trends of the development of "two longitudinal zones" and "five horizontal zones" of overburden fissures and their influencing factors and determined the boundary characterization parameters of gas storage and migration channels based on the comprehensive criteria of "Hf," "S," and "ρ". And evaluated the determination process of gas channels, established, and optimized the theoretical model considering multi-factor mining conditions. The results indicate that gas storage and migration channels mainly develop in the fracture migration zone. The range of development continuously increases with mining height and dip angle and decreases gradually as the working face advance speed increases. It elucidated the temporal variations of gas channels and provides theoretical support for optimizing the layout parameters of gas extraction boreholes and improving gas extraction efficiency.
... At present, the proportion of coal consumption to total primary energy consumption began to decline after implementation of the coal industry rationalization action by the Chinese government (Wang et al., 2020;Yan et al., 2018;Xie et al., 2021). But coal still plays an important role in the development of regional economy, especially the western China economy (Yan et al., 2021;Zhu et al., 2018). Undoubtedly, exploitation of coal resources will do harm to the environment of the ground surface, such as exhaustion of groundwater resources, death of vegetation, cracking of the land, and damage to surface structures, such as railroad tracks, roads, and buildings. ...
Surface damage caused by coal mining is one of the problems perplexing ecological environment restorations in coal mining areas. Accurately evaluating and predicting the degree of surface damage induced by coal mining with reasonable and correct indexes are of great significance to the restoration and treatment of the ecological environment. In this paper, these methods including the unmanned aerial vehicle aerial photography and manual measurement were used to investigate the development characteristics of surface damage caused by 2# coal seam mining in Yangchangwan Coal Mine. The results showed that with the change of mining conditions, the characteristics of surface cracks change obviously, which can be adopted to indicate the degree of surface damage. Thus, based on the results of the investigation, the classification standard of surface damage degree was established based on the evaluation indexes including density of crack, drop height of surface crack, crack width, maximum surface subsidence, and geological disaster caused by cracks and the damage characteristics of buildings. The evaluation method and process of surface damage degree also were given. Based on the ratio of the buried depth to the thickness of the coal seam (H/M), ratio of the thickness of overlying bedrock to the thickness of the coal seam, the thickness of loose layers (Ms), geomorphology, distance to faults, and distance to folds, the prediction model of surface damage degree was built on the GIS platform. The weight coefficient of each prediction index was obtained by the analytic hierarchy process (AHP) method. The surface damage degree map of 2# coal seam in Yangchangwan Coal Mine was divided into four classes: very minor, minor, moderate, and serious, which provides a relatively applicable method for the prediction of surface damage degree in Yangchangwan Coal Mine and its adjacent mining areas.
