Beurteilung der Standsicherheit und Arbeitssicherheit einer Tagebauböschung unter Berücksichtigung aktueller Normen und Richtlinien

To assess the slope stability and occupational safety, a real example was used: a final slope in the gypsum mine of Moldan Baustoffe GmbH & Co KG. As a base for the calculations, a geological report was provided by the company, along with a laboratory tests of the existing rock. The software¿s used for the analyses were SWedge, Slide2, and 3DEC. With SWedge, the failure mechanism of wedge failure was investigated. Based on the known discontinuities, the required cohesion was calculated to achieve a factor of safety of 1,3 while maintaining the same friction angle. In the geological report, three cross-sections with several homogeneous zones were prepared. These sections were analysed using Slide2. In Slide2, the slope was examined under four conditions: without discontinuities, with one discontinuity, with two discontinuities, and with an additional bench. High safety factors were obtained in the cases with no discontinuities and with one discontinuity, and therefore no stability issues were observed. When two discontinuities were included, localized problems were identified¿specifically when wedges or unfavorable geometries were analysed. In this case, the cohesion parameter of the discontinuities was adjusted, until a factor of safety of 1,3 was achieved. For better comparability between the two programs, the same cross-sections were also analysed using 3DEC. However, since 3DEC is a three-dimensional distinct element method (DEM) software, discontinuities could be represented more realistically. All three sections were analysed with rigid blocks, and two sections were additionally analysed with deformable blocks. Here as well, no stability problems were observed using realistic parameters. Subsequently, the discontinuity parameters were reduced, which showed that only small scale block sliding was at risk, and no signs of large-scale failure was observed. Consideration was also given to ÖNORM B 1997, the TAV, and the recommendations of the ÖGG (unpublished). The TAV applies to the occupational safety. With regard to slope stability, various failure mechanisms and calculation methods were investigated.