Study on the stability and control of coal pillars in water-bearing gas extraction boreholes

Driving roadways along goaf with narrow coal pillars can effectively improve the recovery rate of coal resources and the mining replacement relationship, but there is a problem of great difficulty in construction and maintenance, especially under the condition of water accumulation in goaf and high gas content in the mine, the control of coal pillar stability is more important. Based on the engineering background of goaf side entry driving in the 30108 working face of Shiquan Coal Mine, this paper proposes a quantitative characterization method of borehole cracks based on MATLAB image processing in combination with the visual detection technology of boreholes, comprehensively determines the reasonable width of coal pillars in combination with the mechanical model and numerical simulation of soaked coal pillars, and proposes a targeted high-strength asymmetric support scheme and carries out industrial practice. The research results show that the proportion of fracture area in the borehole section decreases in negative logarithm with the increase of borehole depth. When the coal pillar width is 10 m, there is a large range of elastic zones in the coal pillar in the normal section and the gas drainage drilling section, which has a strong bearing capacity. The drainage scheme of goaf and the high strength asymmetric support scheme of "anchor cable mesh beam + narrow coal pillar side cable beam reinforcement + narrow coal pillar side grouting reinforcement" are put forward and put into industrial practice. The roadway control effect is significant and has significant economic benefits.