Abstract
In recent years, bed separation water inrush, as a new type of water disaster, has posed serious threat to mining safety in China’s many coal mines. This study focused on periodic water inrush accidents in the No. 7335 working face owned by Xuzhuang Coal Mine, Jiangsu Province, China. Based on the theory of key strata, the formation positions of the separation layer in the overlying strata were first identified; next, the trapezoid platform model of the fracture of the overlying strata was introduced for illustrating the evolutional process of the bed separation space and accurately calculating the position and the geometrical morphology of the bed separation space. On that basis, the relation between the fracture of the overlying stratum and the inrush of bed separation water was revealed with the use of the plate theory. Moreover, the prevention and control measures of the bed separation water were formulated. Research show that the arrangement of the diversion drilling holes can successfully eliminate the threat of the bed separation water to the lower working face.
Highlights
Coal field is formed by geologic sediments in history
This study focused on the relative position relation between the separation space and the working face, revealed the reasons for periodic water inrushes, and formulated the detection and prevention measures of the separation for adequately removing the safety threat of the bed separation water on the lower working face
When the separation layer was formed between the thick-bedded sandstone stratum and the coal seam can the convergence of bed separation water pose serious threat to the safety in the stope
Summary
Coal field is formed by geologic sediments in history. The strata in most of coal mines are composed of sedimentary rocks mainly including sandstone, sandy mudstone, shale, limestone, and mudstone. Qian et al and Xu et al laid the research emphasis on the fracture and migration rules of the overlying strata after the mining and proposed the key stratum theory, which has provided important theoretical basis for investigating the formation mechanism of the separation layer [17,18,19,20]. Some scholars investigated the water in the separation layer from the perspectives of similarity model, monitoring, and prevention [26,27,28,29,30,31,32,33,34], which can effectively prevent the occurrence of separation-induced water disasters These studies can provide clear idea and helpful reference for identifying and preventing the separation (water) below the overlying thick sandstone in the No 7335 working face owned by Xuzhuang Coal Mine, Jiangsu. The developed bed separation space is larger for the coal seam with greater mining thickness
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