Prediction and Prevention of Water Inrush Hazards from Bed Separation Space

Abstract

The rock plate (RP) method can be used to identify the size and location of potentially dangerous bed separation space (BSS) in coal mines. The RP method is performed in three steps: (1) The rock strata above the coal seam is simplified as a composite plate calculation model; (2) The deflection of rock strata is expressed as a double trigonometric series and obtained using the energy method; (3) The internal-forces and deformation of the RP are solved to determine the size and location of the BSS based on elasticity and a BSS identification process. This requires that the BSS be unbroken, and the BSS upper rock stratum be an aquifer. In this study, the Yuanzigou coal mine was taken as a study case and the RP method was used to determine the size and location of BSS water (BSS-W) above the coal goaf of working face 1,012,001. BSS usually occurs at the contact surface between hard and soft rock strata; at this mine, BSS-W exists between the Yijun conglomerate and the Anding mudstone formations. The results predicted that when the working face advanced 350 m, the third BSS will break, allowing BSS-W to flood into the goaf. These results were verified by borehole video observation. Therefore, two control methods were used: inclined drainage holes drilled from the roadway and spaced holes drilled from the surface in areas with abundant water. This paper thus provides a way to locate the BSS-W and prevent an inrush hazard.