Abstract
The method for determining the upper limit for safe mining with regard to water and sand collapse prevention under thick alluvium and thin bedrock layers is a critical parameter for ensuring the sustainable development of a mine. The height of the water-conducting fractured zone (HWCFZ) is an important index parameter in the prediction and prevention of water and sand collapse. This research was conducted based on the concrete geological condition of the Zhao Gu No. 1 coal mine. First, a field measurement method was used to observe the HWCFZ of a mined panel. The discrete element method was applied to establish a corresponding model, which was calibrated using the measurement data. Then, calculation models for different bedrock thicknesses were developed to analyze the evolution law of the water-conducting fractured zone at different bedrock thicknesses and mining heights. The safe mining upper limits for different bedrock thicknesses were obtained. The relationships between the developing HWCFZ and bedrock thickness/mining height were determined. Using the research results as the main indices, an industrial experiment was performed on the 11,191 panel. The partition limit mining height was implemented in the panel, and safe production was realized. On the basis of the research results, 40,199,336.3 t of coal resources were successfully released, increasing the resource recovery rate by 31.72% and extending the mine service life by 12.5 years. This study not only provided technical support for the sustainable development of the Zhao Gu No. 1 coal seam, but could also be used for safe and highly efficient mining in other coal mines under similar geological conditions.
Highlights
The criteria for the sustainable development of coal resources includes ensuring that their development and utilization cannot exceed the bearing capacity limit of the reserve, while simultaneously achieving the optimal development and utilization within the bearing capacity range
universal distinct element code (UDEC) models were employed to investigate the development of height of the water-conducting fractured zone (HWCFZ) at different bedrock thicknesses and mining heights for the both prediction and forecast and prevention of water and sand collapse
This study provides technical support for the sustainable development of Zhao Gu No 1 coal seam
Summary
The criteria for the sustainable development of coal resources includes ensuring that their development and utilization cannot exceed the bearing capacity limit of the reserve, while simultaneously achieving the optimal development and utilization within the bearing capacity range. Determining the developmental range of the water-conducting fractured zone (WCFZ) is the key to determining the safe mining upper limit. Considerable scientific research has been carried out globally regarding the height of the mining-induced water-conducting zone and practical experience methods for mining underwater bodies. Liu and Qian developed an experience formula that calculates the developmental height of the water-conducting zone based on considerable relevant theoretical research and practical explorations in this area. 11 ccooaall sseeaamm iiss ddiivviiddeedd iinnttoo sseevveenn aarreeaass aaccccoorrddiinngg ttoo tthhee bbeeddrroocckk tthhiicckknneessss,, aass sshhoowwnn iinn FFiigguurree 11. Reasonable physical and mechanical parameters for the coal and rock mass were determined in the model, and combined with the bedrock thickness contour zone and water-conducting fracture zone); the numerical simulation results were calibrated using the mSuestaisnuabrielidty ‘2t0w17o, 9z, o10n7e7’ height. Reasonable physical and mechanical parameters for the coal and5roofc1k9 mass were determined in the model, and combined with the bedrock thickness contour map (Figure 3) tmoadpet(eFrimguinree a3)retoasdoentaebrmle iunpepaerremasinoinnagblliemuitp.pEexrpmeriinminegntlaiml sittu.dEixeps ewriemreecnotnaldsutcutdediersewgaerrdeincognfdraucctuterde dreegvaerldopinmgefnrtacintuorveedrleyvineglosptmraetan,taisnwoevlleralsytihneg esftfreacttas,oafsthweemll iansintgheheeifgfhecttosnoffrathcteurmeidneinvgelohpemigehnttoant dfriaffceturernetdbeevderloocpkmthenictkantedssifefseraenndt bmeidnrioncgkhtehiigchktnse. sses and mining heights
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