Abstract
The paper investigates the permeability of large-scale boundary fault and its impact on coal pillar design, focusing on the major large-scale boundary reverse fault labeled as F22 and the derived reverse fault labeled as FN1 in the III3 mining area of Zhuxianzhuang coal mine, which is belong to the Huaibei Mining Bureau. Employing a comprehensive approach integrating on-site sampling, laboratory test, underground water discharge tests, numerical simulation, and analog analysis, the aquifer conductivity of the fault is obtained. Drilling sampled the fault zone and surrounding strata, followed by X-ray diffraction (XRD) tests and microscopic observations to determine mineral composition and microfracture structure characteristics, yielding preliminary permeability analysis. Underground water discharge tests confirmed that F22 is a non-water-conducting fault under undisturbed conditions. Subsequently, a numerical model incorporating the mining area's major large-scale boundary fault was established based on stratigraphic profiles of prospecting lines, analyzing mining-induced changes in aquifer conductivity of the F22 and FN1 faults during the excavation of 10th coal seam. Results show the FN1 fault acting as a stress barrier during mining, becoming the primary water inrush channel post-excavation. Finally, complying with regulations, we determined the width of water-proof coal pillar for the FN1 fault aligning with simulation findings. These insights and methodologies are crucial for the safety management of large-scale boundary fault in Zhuxianzhuang coal mine and similar mining conditions.