Abstract: In order to guarantee the mining safety of isolated working face, the safety parameters of the pressure relief boreholes have to be determined scientifically. The borehole pressure relief radius range under the geological condition of No.8939 panel was obtained by theoretical calculation. Then combined with numerical simulation method, from the perspectives of stress and energy, the theoretical calculation results were verified. Then, a field measurement plan was worked out according to the results. The yielded range and spacing between pressure relief boreholes were measured by BOTDR technology on site. The results show that the larger the size of pressure relief boreholes is, the better the pressure relief effect will be, and the greater the disturbance to the coal seam will be, so an oversize pressure relief borehole may induce the rockburst, that borehole spacing has a critical value, when the borehole spacing is less than the value, the deformation degree of coal seam is large and the pressure relief effect is better, and when the borehole spacing is higher than the value, the deformation degree of coal seam is weak and the pressure relief effect is marginal, and that for the geological condition of No.8939 panel, the suitable values of the diameter and the spacing are108 mm and 0.7 m respectively. The research results ensure the mining safety of the No.8939 panel.

Key words: safety parameters, rockburst prevention and control, pressure relief borehole, brillouin optical time domain reflectometry(BOTDR), micro-seismic monitoring