Title page for ETD etd-07082005-141037

Document Type Master's Dissertation
Author Drescher, Karsten
URN etd-07082005-141037
Document Title An investigation into the mechanisms of time dependent deformation of hard rocks
Degree MSc (Mine Strata Control)
Department Mining Engineering
Advisor Name Title
Prof M F Handley Committee Chair
  • mineral industries
  • rock excavation
  • mining engineering
  • rock mechanics
Date 2003-04-01
Availability unrestricted
The testing undertaken for this dissertation is intended to help quantify the various time-dependant deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated and two different hard rock types, Ventersdorp Lava and Elsburg Quartzite were used. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. An important conclusion made is that the relationship between grain size and infilling thickness is more important than previously might have been assumed. The last part of the study consisted of triaxial post-failure relaxation tests. As far as could be determined, this is the first time triaxial post-failure tests were attempted, particularly on typical South African hard rocks. An important finding of this study is that during compression creep as well as during triaxial post-failure relaxation the amount of energy dissipated for the lava is significantly less than for quartzite. For mines operating at great depth (more than 2000m) the implication is that the rock material might relax much more slowly than might have been assumed and this means that after failure the rock mass continues to store large amounts of strain energy. This study provides the first data available for energy change calculations in fractured rock masses. Three mechanisms of time-dependant deformation were quantified providing valuable data for numerical investigations.

2002, 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:

Drescher, K 2002, An investigation into the mechanisms of time dependent deformation of hard rocks, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07082005-141037/ >


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