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The evaluation and design of tunnel support by means of numerical modelling

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dc.contributor.advisor Naismith WA en
dc.contributor.author Lewis AN en
dc.date.accessioned 2016-09-22T11:26:45Z
dc.date.available 2016-09-22T11:26:45Z
dc.date.submitted 1996 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/121880
dc.description.abstract The results of a survey into tunnel development have shown that the South African gold mines develop more than 800km of tunnels annually. Approximately 20% of these tunnels have to be rehabilitated before the end of their service life. Numerous empirical design procedures and formulae have been developed, to design support systems for these tunnels. Although these procedures and formulae have provided successful guidelines in particular circumstances, they could rarely be generalized or used to predict the response of rock or rock masses under different and untried loading conditions. Empirical methods for tunnel support design have not been successful in some of the deep level haulages on Hartebeestfontein Gold Mine, and the numerical modelling approach for tunnel support design was suggested.<br><br> The aim of the project was to develop a method to effectively and scientifically design tunnel support systems. In order to do this, the field stresses and the rock mass properties had to be established. The stresses were calculated with MTNSIM-D and the rock mass properties were established by means of a rock mass classification. Uniaxial and triaxial laboratory tests on rock specimens were carried out to establish the rock material properties. A procedure to downgrade the rock material properties to rock mass properties was proposed and used in this project.<br><br> FLAC is a two-dimensional numerical programme which can simulate the linear or non-linear behaviour of rock masses under certain stress and strain conditions. This programme was used to establish a numerical model for the 78A level haulage on Hartebeestfontein Gold Mine.<br><br> Several closure stations and extensometers were installed in the haulage to quantify the closure and the depth to which closure in the tunnel extends.<br><br> The downgraded rock material properties were used in the numerical model to correlate the underground observations and the model. This model was then used to design a new support system for the 78A haulage on Hartebeestfontein Gold Mine.<br><br> The model showed that there is no significant difference in the dilation in the tunnel when lm, 2m or 3m long support elements are used, and it was suggested that a trail section in the haulage is used to test this finding.<br><br> The same model showed that the hangingwall closure could be significantly reduced by installing an additional support element in the hangingwall on the centre line of the tunnel. It is suggested that the additional support element in the hangingwall should be implemented in the 78A level haulage, because of the significant benefits.<br><br> The objective to scientifically design a new support system for the 78A level haulage by means of numerical modelling was therefore achieved. en
dc.language English en
dc.title The evaluation and design of tunnel support by means of numerical modelling en
dc.type Masters degree en
dc.description.degree MSc(Eng) en


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