Analysis of seismic tomography data for definition of hydraulic fracturing parameters in underground coal mines

The article analyzes the issue of reliable estimate of the unloading extent and the variation order of coal-rock massif geomechanical characteristics as a result of hydraulic fracturing undertaken from mine workings. For this purpose it is proposed to use the fracturing value of the studied rock mass. In case the possibility of comparison with geological and actual data doesn’t exist, the option of using the rock mass classification based on the estimated value of geophysical index that specifies rock mass fracturing is considered. To address the issue, a geophysical survey of the active roof at the excavation site in the operating coal mine was implemented with a method of a seismic radioscopy before and after hydraulic fracturing. According to the results of seismic exploration, a massif unloading degree and an extent of roof fracturing has been determined.