In the Carboniferous rock mass of the Upper Silesian Coal Basin, large changes in the geomechanical conditions often occur over relatively short distances. These conditions relate to rock properties that are primarily responsible for the occurrence of geodynamic phenomena in the rock mass. The main factor influencing the manifestation of these phenomena is tectonic stress developed during Variscan and subsequent Alpine orogenesis. This stress contributed to creating tectonic structures in the Carboniferous formations and influenced the properties of the rocks themselves and the rock mass they form. As a result of the action of the stresses, compaction zones (main stresses were compressive) were formed, along with zones in which one of the main stresses was tensile. For the compaction zones in the Carboniferous rocks, the following geomechanical parameters have been calculated: uniaxial compressive strength, Young’s modulus and post-critical modulus. The local stress field was determined according to the focal mechanism in selected areas (Main and Bytom troughs) to characterize changes in geomechanical properties of the rocks that are responsible for high-energy tremors (E ≥ 106 J, ML ≥ 2.2).
The article contains considerations on possible actions directed at increasing productivity of hard coal mining industry. It is necessary to improve the state of the industry, and ensure its survival. Basic definitions and measures concerning productivity and management were presented to illustrate examples referring to a mining enterprise. Then, basing on organizing, one of the management functions, the issue of productivity in a mining enterprise and its influence on improving effectiveness of operational management, was analysed. An assumption was presented that solutions concerning identification of sources and volume of costs, hitherto existing in mining enterprises, ought to be complemented with the planning function following process approach. It can be the starting point for decisions of economic feasibility of given deposits, seams or parts of them, before mining operations start, and to control incurred costs in process approach. The article is summed up with a process algorithm of cost management.