Determination of Save Excavation Criteria in Velenje Coal Mine

Abstract

Ensuring safe conditions for mining coal under water-bearing sands in the Velenje coal mine depends on the designed parameters of hydrogeology, geomechanics and drainage. The purpose of the research is to predict and simulate the hydrostatic pressures above the excavation fields in order to determine the thickness of the insulation layers and the height of the excavation. Coal occurs in the Velenje basin in the form of a slightly concave lens. Directly above the coal seam is an insulating layer of marl or clay. Above the insulating layer are more or less permeable Pliocene sands in which water can accumulate under layer pressure, posing a potential risk of water ingress into underground spaces. In addition to the Pliocene sands, triad layers of different ages and lithology in the bedrock also pose a risk of water intrusion. In order to prevent the intrusion of water into the working areas of underground objects, the criteria for safe mining in the Velenje coal mine under aquifers were established. The scientific research approach to determining the criteria for safe mining enables the safety and determination of excavation heights in coal mining. The following data are required for such a calculation: the water pressure in the first sands, the excavation depth below the surface, the thickness of the insulating layer and the method of excavation or the course of the demolition processes.