Mechanical criteria and sensitivity analysis of water inrush through a mining fault above confined aquifers
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ORIGINAL PAPER
Mechanical criteria and sensitivity analysis of water inrush through a mining fault above confined aquifers Jian Sun 1,2 & Lianguo Wang 2 & Yang Hu 2 Received: 20 December 2017 / Accepted: 17 December 2018 / Published online: 28 December 2018 # Saudi Society for Geosciences 2018
Abstract A mechanical model of water inrush through a mining fault in the workface above confined aquifers was developed according to ground pressure and strata control theory. Based on limit equilibrium theory of rock mass, mechanical criteria of the water inrush through the mining fault in the workface above confined aquifers were deduced by considering Mohr–Coulomb yield criterion. Five influencing factors, namely fault dip, fault cohesion, fault internal friction angle, suspended goaf range behind the workface, and thickness of floor strata protective zone, were selected from the mechanical criteria of an ultimate hydraulic pressure that the stope floor strata with a fault can tolerate. An orthogonal test was performed to analyze the sensitivity of the ultimate hydraulic pressure tolerated by the stope floor strata with fault. Results show that the fault dip and thickness of the floor strata protective zone significantly influence the ultimate hydraulic pressure tolerated by the stope floor strata with fault and represent 32.8% and 32.5% of the total effects, respectively. The fault cohesion, fault internal friction angle, and suspended goaf range behind the workface exert similar effects on the ultimate hydraulic pressure that the floor strata with a fault can tolerate and comprise 10.5%, 13.5%, and 10.7% of the total effects, respectively. The ultimate hydraulic pressure that the stope floor strata with a fault can tolerate decreases with the increase in the fault dip, fault internal friction angle, and suspended goaf range behind the workface but increases with the fault cohesion and thickness of the floor strata protective zone. This property decreases with the distance between the coal wall of the workface and the fault. This study provides insights into the water inrush mechanism through the mining fault in the workface and its corresponding sensitivity, thereby aiding in establishing the safe mining of coal seam with fault above confined aquifers. Keywords Water inrush through fault . Ultimate hydraulic pressure . Mechanical criteria . Sensitivity
Introduction The geological conditions in China are extremely complex that geological disasters occasionally occur in coal mines despite abundant coal reserves in this country (Gao et al. 2018; Guo et al. 2017; Miao et al. 2004; Qian et al. 2003a). The mining workface encounters increasing threats from Ordovician karst water from coal seam floor with the increase in depth and intensity of coal mines. The prediction and prevention of water inrush in the mining workface with fault structure are novel
* Jian Sun [email protected] 1
School of Energy and Safety, Anhui University of Science and Technology, Huainan 232001, Anhui, China
2
State Key Laboratory of Coal Resou
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