Terrain surface subsidence observed in mining areas results in the flattening of riverbeds and their embankments. This leads to increasingly deep erosion and siltation of riverbeds and surface currents, which causes the emergence of permanent overflow lands. This paper presents hydro – engineering solutions applied in the areas of the mining activity of JSW S.A., which serve the purpose of repairing and eliminating mining damage in the existing infrastructure. The presented repair measures make it possible to eliminate the threat of flooding in mining areas.
The primary aim of this study is the analysis of the influence of multi-seam coal mining on a specific 110 kV overhead high-voltage power line. The paper presents the results of geodesic measurements of surface deformation in the area of the analysed location. The study also analyses mining-induced changes in the construction and the inclination of the transmission pylons. Some proposals for the reinforcement of the pylons are suggested. Additionally, pressing issues are identified indicating the necessity for the replacement of the existing pylon system of the overhead high-voltage power line.
This paper presents an analysis of the parameters of surface deformation prediction theory carried out for a hard coal mine in the Upper Silesian Coal Basin. Two areas of the coal mine were used as the subject of this analysis – in these areas, underground mining with roof caving was carried out in similar geological conditions for various numbers of seams, and consequently, for various rock mass disturbance rates. In order to estimate the parameters of the surface deformation prediction theory, i.e. the exploitation coefficient and the angle of the main range of influences, geodesic measurements of subsidence along the observation lines were used. The study shows that rock mass disturbance affects the values of the Knothe theory parameters and the values of the surface deformation indicators. In the case of a larger number of selected seams, the determined value of the exploitation coefficient was larger than the determined value in the case of a less disturbed rock mass. Assuming inappropriate parameters for surface subsidence prediction may cause unexpected damage to surface objects.
The paper presents the application of a 3D laser measurement technology in a modern monitoring of roadways. The authors analyze the possibility of using a three-dimensional scanning measurement of longwall working dimensions. The measurement results are presented in the form of a cloud of points obtained from a 3D laser scanning. The paper also presents a comparison of the results obtained from the convergence of traditionally-made measurements with the measurements derived from the threedimensional scanning and discusses possible methods of comparing different point clouds.
The paper presents an analysis of seismic activity for selected areas of hard coal mine executing exploitation in a rock mass with a variable degree of rock disturbance, i.e., also with a varied number of previous mined-out seams. A distribution of vertical stress and a value of vertical stress concentration coefficient were also determined in the strata of immediate roof of the seams planned for mining. In the analyzed case, despite the lack of thick and solid strata of sandstones in the roof, the rock mass emits seismic activity, where the energy largely depends upon an impact of exploitation edges and tectonic disturbance.
Back in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to >1,000 m. Design, excavation and maintenance of mining roadways at the depth of >1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)
This article presents the impact of the retreat mining (i.e., involving an intended collapse of the excavation roof, subsequent to extraction) on the subsidence of the ground surface. The analysis was carried out for two areas of coal underground mining located in the Upper Silesian Coal Basin (Górnośląskie Zagłębie Węglowe). The assessment of the influence of exploitation on the ground surface was based on the results of geodetic measurements performed over a long period of time, whereas the land deformation prediction was made with the use of the EDNOPN program. The calculated and the predicted values were further compared, and the parameters of theory were determined. The results discussed in this paper have been shown by way of diagrams. The observed differences in the processes of vertical displacement were used in the analysis which took into account the degree to which the rock mass had been disturbed during the previous excavations, as well as the type of incumbent rock in the area under study.
This paper investigates the influence of extraction on the surface in the area of the Pszczynka river. The mining-enhanced terrain subsidence hitherto observed has also resulted in the subsidence of the riverbed and its embankment. Some geotechnical solutions are proposed, including the reconstruction and repair of damage to the existing infrastructure. Such measures should facilitate a proper flow of water in the riverbed which is similar to a natural flow.