Experimental approach to measure stress and stress changes in rock ahead of longwall mining faces in Czech coal mines

The measurement and monitoring of stress in rock mass are very important tasks in mining geomechanics. With increasing mining depth and worsening of the geological and mining conditions, a suitable method to determine and monitor rock stress and stress changes due to longwall coal mining is needed. Detailed knowledge of the stress state in rock mass is very useful when designing safe mining activity, especially in rockburst areas. The paper presents a brief description of the Compact Conical-ended Borehole Monitoring (CCBM) method for rock stress evaluation and the technical details of this innovative technology. The second part of the contribution evaluates and discusses initial results and experience obtained from the use of CCBM equipment for determination and observation of mining-induced stresses during mining of selected longwall panels in the conditions of the deep coal mines of the Upper Silesian Coal Basin.