Abstract
Water inrush disasters from the coal seam floor occur frequently due to the high water pressure of the Ordovician limestone aquifer, multiple aquifers and strong mining disturbance. We presented a model of water-resisting key strata (WRKS) to investigate the mechanism of floor water inrush from multiple aquifers in deep coal mines. Roof hydraulic fracturing (RHF) for controlling floor water inrush and multi-parameter monitoring were proposed and validated in the Xingdong coal mine in Xingtai, Hebei Province. The results indicated that the periodic weighting step of the test working face after RHF was 9.53 m, which was 61.42% less than that of the working face without RHF (24.7 m). The floor failure depth was 30 m, which was 34.4% less than that of the zones without RHF (45.7 m). Hydraulic fracturing weakened the strength of the overlying strata to control the weighting step and reduce the mining disturbance stress, and the stability of the floor WRKS was enhanced, thereby preventing water inrush from the coal seam floor. The research results provide a solution for preventing floor damage and floor water inrush under strong mining disturbance and in complex hydrogeological environments in deep mining.
Highlights
Water inrush from the coal seam floor is a dynamic disaster in coal mines [1,2,3]
The results showed that the Roof hydraulic fracturing (RHF) shortened the weighting step and increased the load on the floor in the mining area, which enhanced the stability of the water-resisting key strata (WRKS)
A WRKS model of the floor in goaf was established to explore the mechanism of water inrush from the coal seam floor
Summary
Water inrush from the coal seam floor is a dynamic disaster in coal mines [1,2,3]. Mine water inrush has always been a critical technical problem limiting the safe production of water-rich mines [4,5,6]. Underground drainage from coal mines has caused many ecological and environmental problems [7,8]. North China Carboniferous-Permian coalfield are transitioning to deep mining or exploring lower coal groups. Deep rock mass is located in an environment with high in situ stress and high water pressure [9], and the risk of floor water inrush is increased [10]. It is of great significance to investigate the mechanism and prevention technology of floor water inrush in deep mining
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