Monitoring and Analysis of Waterproof Coal Pillars Under the Influence of Goaf Water

Performing stability studies of waterproof coal pillars is one of the key measures for preventing mine water disasters. As some areas of the coal pillar were affected by goaf water in the Nanhu Second Mine, the coal pillar and surrounding roadway were somewhat deformed. To investigate whether the pillar can ensure safe production in the mine, the source of goaf water and the direction of water infiltration were analyzed using exploration holes, and it was concluded that the goaf water originated from the V3 aquifer and was static. Thus, a theoretical analysis was carried out to determine the relationship between the mechanical parameters of the coal and rock structures affected by water. On this basis, a numerical simulation was employed to examine the key changes in the coal pillar and roadway affected by goaf water. The simulation results showed that the plastic area was 6–11 m and the elastic area in the middle was 6–8 m after excavating the working faces on both sides of the coal pillar, and the water flow vector of the aquifer could not pass through the pillar. Finally, in situ monitoring using ground-penetrating radar, deformation measurement, and loosening circle detection revealed that the development degree of internal cracks in the coal pillar was relatively light; thus, the pillar could effectively prevent water damage. These monitoring and analysis methods comprehensively evaluate the stability of the coal pillar and provide a guarantee for the safe mining of the working face.