Document Type	Master's Dissertation
Author	Selomane, Mmathapelo Annah
Email	mmathapelo.selomane@exxaro.com
URN	etd-08032012-145737
Document Title	Back-analysis and design review of a failed slope at an open-pit coal mine, Mpumalanga, South Africa
Degree	MSc
Department	Geology
Supervisor	Advisor Name Title Prof J L Van Rooy Supervisor
Keywords	Mpumalanga back analysis generalised Hoek-Brown failure criterion sensitivity analysis probability of failure factor of safety circular failure
Date	2012-04-13
Availability	restricted
Abstract Mining activity in open-pit mines may change material properties over time and as a result, shear strengths are reduced and may lead to slope failures. It is therefore important to design slope geometries with an acceptable probability of failure. In the event of slope failure occurring, the process of back-analysis to determine material properties at failure may lead to slope redesign for safety reasons. A case study is presented from the back-analysis performed on a slope failure at an open-pit coal mine in the Mpumalanga Province, South Africa. The failure occurred during December 2008 and is believed to be a progressive failure where failure in one material triggered failure through another. Back-analysis, using the method of slices, was performed to obtain material properties at failure with the aim of redesigning the slope. The back-analysis included sensitivity and probabilistic analyses using the 2D limit equilibrium slope stability analysis program, SLIDE (© Rocscience). A sensitivity analysis was performed to determine the material property with the most significant influence on the stability of the slope (factor of safety), and a probabilistic analysis was also performed to determine the likelihood of the proposed new slope geometry to fail during future mining activity. The new slope geometry that is proposed has an acceptable probability of failure and an adequate factor of safety. The influence of groundwater does not seem to have a significant effect on the new slope design, based on sensitivity groundwater analyses. Copyright © 2012, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Selomane, MA 2012, Back-analysis and design review of a failed slope at an open-pit coal mine, Mpumalanga, South Africa, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-08032012-145737 / > E12/4/470/gm
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