Gas Drainage Technology of Floor Strata Boreholes in Contiguous Upper Protective Seams

According to the large amount of gas emission problems during the working face mining in contiguous upper protective seams, in combination with the a nalysis of the mining effects in contiguous upper protective seam floor and the law of gas flow in protected seam, the gas drainage technology of floor strata boreholes i n contiguous upper protective seam was put forward. The experiment was carried out in No. 3527 working face of Zijiang Mine protective seam, the results showed that the maximum gas drainage concentration was 50%，the drainage quantity was 0.81 ~ 2. 03 m3/ min, 1. 47 m3/ min in average. The effective drainage range of floor str ata boreholes was determined, and the gas control of working face in contiguous upper protective seam was realized.