Seismological Activity During Room and Pillar Hard Coal Extraction at Great Depth

Abstract

A first attempt of using the Room and Pillar mining method in the Czech Republic was implemented in the southern part of the Upper Silesian Coal Basin. This stratigraphical unit is well known for its complex geological structure with more than 40 main coal seams vertically distributed in the area of about 122 km2 of active mines and a complex slide/overlap fault system. The fact that the extraction of coal by this method is realised at a depth around 900 m below the surface has also made it one of the deepest Room and Pillar mining sites in the world. These facts brought lead to several questions. The main question connected to sustaining the safety of the workers before and after the advance of the mining works has resulted in this study of the prediction of unnatural seismological activity based on data that were collected during and after the excavation of the coal seam. Also, we ask whether the methods can be used for the prediction of inhomogeneous stress distributions in this kind of openings. Seismological monitoring, which is the main goal of this paper, was supplemented by stress and deformation measurements in coal pillars and surrounding rocks. More stations were added to the network of seismic stations of the coal mine at different levels surrounding the Room and Pillar site. We give the first results of the evaluation of seismic activity during the driving of the roadway in the first mining panel. We describe the site and mining conditions, details about seismological network, and a comparison of seismic activity with the gate driving advance and creation of coal pillars. This is compared to stress changes in the coal pillars.