Browsing by Author "Greyling, Deon"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Evaluating five mine residue disposal facility case studies using a limit equilibrium method of slices.
    (Stellenbosch : Stellenbosch University, 2024-03) Greyling, Deon; MacRobert, Charles; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: In this study, five slope failure case studies, associated with mine waste facilities, such as Tailings Storage Facilities and Waste Rock Dumps, are evaluated using the Morgenstern-Price Limit Equilibrium Method of Slices. The available information of each study has been studied and key information about its investigation, soil test work, pre-failure slope geometry, and the piezometric surface have been extracted to develop a set of limit equilibrium slope stability models. The models were used to search for the critical slip surface and to back-calculate the shear strength of the critical soil region that satisfies a computed factor of safety of unity. The critical slip surfaces, determined from the limit equilibrium models, closely resemble the observed performance of the studied slopes. The back-calculated shear strength parameters of the critical soil region are compared to shear strength parameters derived from laboratory test results and typical values published in the literature. The back-calculated values compared well to the shear strength values published in the literature for similar soils. However, in two cases the back-calculated values did not compare well to values derived from laboratory test results. In both cases, direct shear tests were completed on fine-grained soil, which may have led to erroneous results. In two case studies, the back-calculated values compared well to the test results, and in another, the back-calculated shear strength is between the peak and residual shear strengths derived from laboratory test results. For three case studies, an additional analysis was done where two empirical correlations was used to specify the fully softened shear strength and residual shear strength of finegrained soil. The results of the slope stability models showed that the stability of the slopes is sensitive to the porewater pressure regime, emphasising that it should always be appropriately accounted for in the analysis of a slope that has a consequence of failure. Furthermore, the results of the analyses highlight that the engineering properties of the soils comprising the slope and its foundation should be sufficiently characterised and verified through appropriate geotechnical laboratory and in situ test work. The analyses affirm that the Morgenstern-Price Limit Equilibrium Method of Slices is a suitable tool to investigate slope stability provided that the piezometric surface, soil parameters and slope geometry are accurately defined.