The traditional design methodologies for tunnel and underground excavations are divided in to three categories: Empirical, Analytical, and Observational approaches, whereas in the last years the Numerical approach has strongly become popular both for the intrinsic simplicity of the software packages and their ability to manage problems unsolvable with the classic methods. In this thesis, the underground openings have been analyzed using constitutive models other than the Mohr-Coulomb theory. FLAC is used for the analysis and the software has been implemented to include the Polyaxial Strength Criterion. The details of the modifications made in the software are presented and the results are compared with the Singh's elasto-plastic stress distribution in squeezing grounds. The applicability of the Polyaxial Strength Criterion has been therefore extended to all the numerical suites designed for geo-mechanical purposes (FEM, FDM, …) and the obtained results compared to the observations of deformation and radial squeezing pressure of the instrumented tunnels in the Chibro-Khodri underground power station. This study will develop better comprehension of the behavior of the underground openings and also provide a useful tool to the designers in the planning stages. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.

The design of support systems, comprising rock bolt reinforcement and fabric containment components for tunnels in deep level mining environments does not currently cater well for adverse rock mass conditions. This often results in periodic failure of the support system, particularly under dynamic (rockburst) conditions with the potential for total collapse of the excavation. The design of support systems is currently based either on empirical design guidelines often not applicable to this environment or simple mechanistic models. This thesis details a methodology for the rational design of tunnel support systems based on a mechanistic evaluation of the interaction between the components of a support system and a highly discontinuous rock mass structure. This analysis is conducted under both static and dynamic loading conditions. Due to the highly complex and variable nature of the rock mass structure and the dynamic loading environment, a large component of the practical work on the evaluation of the mechanisms of rock mass deformation and support interaction is based on rockburst case studies. The understanding gained from these investigations is further evaluated by means of laboratory testing of the performance of the components of the support systems and numerical modelling of the interaction of the components of the support system with the rock mass. Due to the complex nature of this design environment the methodology developed in this thesis is but a step towards our greater understanding of the behaviour of the rock mass, and the interaction of support systems in the stabilisation of tunnel excavations. However, in comparison to the current design, this methodology now allows the design engineer to make better estimations of the anticipated demand on the different components of the support systems, under a defined rock mass environment on engineering principles. This understanding will give the design engineer greater flexibility, and confidence to design the appropriate tunnel support system for a specific rock mass and loading condition based on the often limited availability of different support units in the underground mining environment. / Thesis (Ph.D.)-University of Natal, Durban, 1999.

With the extension of the Nchwaning Mine shaft complex in the Northern Cape Province, various geological and geotechnical complications needed to be identified in order to ensure correct use of tunnelling methods and support techniques. An understanding of the geological history of the area and the resulting geotechnical nature was important in defining the rock mass quality ahead of shaft development. A total of 12 geotechnical boreholes were drilled, and an additional 18 old boreholes revisited to accurately detennine the stratigraphy, geological structure and associated weathering effects. Various soils and rock testing helped quantify the materials encountered. Sands of the Gordonia Fonnation form the surface cover of this area, and together with the weathered calcrete, calc-arenite, conglomerate and clay, they form part of the Cenozoic Kalahari Group. The 30m thick basal unit of red clay is common throughout this region. This silty clay material is problematic in that it is expansive and hygroscopic. The clay unit rests unconformably on folded, faulted and highly weathered shale of the Proterozoic Lucknow and Mapedi Formations of the Olifantshoek Supergroup. Unconformably below this sequence lies the manganiferous ore deposits of the Hotazel Member, which is contained within the Voelwater Formation of the Griqualand West Supergroup. For the development of the decline shaft through the Gordonia Formation a box cut was excavated to a depth of 25m. The anticipated poor geotechnical conditions for a further 125m below the Gordonia sands called for high quality permanent tunnel support in the upper weathered horizons. Barton's Q-analysis was adopted as a recognized tunnelling quality index to predict and quantify the rock mass characteristics ahead of the shaft. The highly variable and generally low Q-values from borehole core analysis indicated that precast tunnel lining be used for 800m (at 11.5°) through the entire weathered Cenozoic sequence and into the weathered shales immediately below the Red Clay. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

Thesis(M.Eng.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 96-99.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 147-154) Also available in print.

Thesis (M. S.)--Stanford University, 2001. / Submitted to the Department of Geological and Environmental Sciences. Copyright by the author.

Thesis (M. App. Sc.)--Carleton University, 2003. / Includes bibliographical references (p. 182-187). Also available in electronic format on the Internet.

Mémoire (M.Sc.T)--Université du Québec à Chicoutimi, 1996. / Document électronique également accessible en format PDF. CaQCU

Thèse (M.Sc.T.)--Université du Québec à Chicoutimi, 1996. / Document électronique également accessible en format PDF. CaQCU

Thèse (Ph.D.)--Université du Québec à Chicoutimi, 2000. / "...pour obtenir le grade de docteur de l'Université Bordeaux I - France et comme exigence partielle au philosophiae doctor de l'Université du Québec à Chicoutimi - Canada. Spécialité: mécanique" La thèse avec ses annexes sont accessibles via le curriculum vitae, section "COMMUNICATIONS". CaQCU CaQCU Document électronique également accessible en format PDF. CaQCU