... in the experiment volume was the orientation of the experiment drift and its geometry. To maximize the tangential stresses on the boundary of the drift, it is oriented perpendicular to 1. To further increase the stress magnitudes the height of the drift is set to 7.5m. The floor of the drill-and-blast drift...

... the floor. Here thick coal seams are, first, developed with normal height pillars along the floor and then the overlying coal band is taken during retreat of the face by longhole drilling and blasting. This pattern of roof coal winning created a higher goaf, resulting in an increase in the height of pillars...

...1 INTRODUCTION Geological parameters such as foliation, acting as weakness planes in the rock, may have a high impact on the fragmentation process underneath rock cut- ting tools. Extensive field and laboratory studies have been performed to examine drilling or cutting progress in correlation...