Abstract
This paper focused on the height calculation of water flowing fracture zone during mining under the Ordovician limestone nappe aquifer. According to the critical conditions of crack arresting under the action of compression‐shear stress, a formula for calculating the height of water flowing fracture zone during mining under the Ordovician limestone nappe aquifer was proposed, which takes tectonic stress, the influence of fault, the mechanical effect of the seepage field on the stress field, and the rock softening with water into consideration. The formula was applied to calculate the height of water flowing fracture zone above panel E3213 in the first eastern mining area of the Qianyingzi coalmine. The comparison between the theoretical calculation and the measured result shows that the formula proposed in this paper is closest to the measured value and further improves the calculation accuracy compared with the previous formulas. This study not only has important theoretical and practical significance for the safe mining of Qianyingzi coalmine, but also has important theoretical and practical significance for the coalmine facing the double threat of Ordovician limestone confined aquifer and reverse fault.
Highlights
Introduction e NorthChina coalfield occupies a very important position in the distribution pattern of coal resources in China at the present stage, with abundant reserves
In this paper, according to critical conditions of crack arresting under the action of compression-shear stress, and from the perspective of the evolution of the crack propagation of the damaged rock mass, a formula for calculating the height of water flowing fracture zone with mining under a double threat from both the fault and roof confined water was proposed, which takes tectonic stress, the influence of fault, the mechanical effect of the seepage field on the stress field, and the rock softening with water into consideration
(2) By comprehensively comparing the theoretical values obtained from the five groups of calculation schemes with the measured values of the height of the water diversion fracture zone in stope, the calculation result of scheme 5 is closest to the actual value. erefore, the height of water flowing fracture zone of coal seam mining under Ordovician nappe aquifer should comprehensively consider the influence of confined aquifer water pressure, tectonic stress field, and fault
Summary
Is paper focused on the height calculation of water flowing fracture zone during mining under the Ordovician limestone nappe aquifer. According to the critical conditions of crack arresting under the action of compression-shear stress, a formula for calculating the height of water flowing fracture zone during mining under the Ordovician limestone nappe aquifer was proposed, which takes tectonic stress, the influence of fault, the mechanical effect of the seepage field on the stress field, and the rock softening with water into consideration. Due to thrust fault, the Ordovician limestone aquifer was pushed to the above coal roof in this area, which has characteristics of karst fissure development and good water abundance. In this case, the Ordovician limestone aquifer becomes a great threat to coal mining.
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