LAUSR

Abstract Gas drainage through boreholes can effectively reduce gas disasters and significantly promote the efficient drainage and clean utilization of gas during mining activities. Gas drainage boreholes will deform and fail as the mining proceeds, but there is a lack of effective measures for real-time monitoring of borehole stability currently. Concerning this problem, a new test system was discussed to measure borehole deformation in this study. Further, an index for calculating the destructive degree (DD) of boreholes based on the residual area was proposed, and a coupling relationship between the relative pressure (RP) of sensors and DD was established as well. Moreover, the calculation model of DD was modified to determine the determination conditions of borehole failure. Finally, effectiveness of the test system was verified in a mining coal seam. The results show that DD first surges with time and then tends to stabilize, as verified by gas drainage quantity. Spatially, DD first rises and then declines with increasing depth, which agrees with the coal stress distribution and the simulation results. The study can enlighten the deformation measurement and failure determination of gas drainage boreholes.