Mechanics Criterion of Water Inrush from the Coal Floor under Influence of Fault and Its Engineering Application

Abstract

In order to investigate the impact of fault on the stability of the water-resisting layer of the coal floor, the critical water pressure formula of the water-resisting layer failure under the influence of fault is deduced respectively by using brittle fracture criterion in fracture mechanics and the shear failure limit equilibrium condition in rock mechanics. The corresponding mechanics criterion of water inrush from the coal floor is proposed. Then the critical water pressure affected by the width of the coal pillar, the thickness of water-resisting layer, the dip angle, and mechanical property of fault is analyzed and discussed. Finally, the validity of the proposed mechanics criterion of water inrush is verified by the example analysis of coal mine engineering. The results show that (1) the smaller the dip angle of fault, the less the critical the water pressure, and the floor is more prone to water inrush; (2) the critical water pressure is positively correlated to the cohesion of fault. The smaller the cohesion of fault, the greater the possibility of water inrush; (3) the bigger the coal pillar width, the larger the critical water pressure, and the floor is less prone to water inrush; and (4) the critical water pressure linearly increases with the thickness of the water-resisting layer. The larger the thickness of the water-resisting layer, the smaller the possibility of water inrush.