This thesis presents ground control best practices in weak rock environments including an augmentation to the existing Span Design curve by adding 463 case histories of RMR76 values ranging from 25 to 60. A Neural Network analysis of this data has been added and compared to the existing Span Design data of 292 case histories. Ground support is almost always used in weak rock environments, though the type of support used can vary widely. The development of the weak rock augmented Span Design Curve has also been calibrated to four different support categories; Category A: Pattern Friction Sets, Category B: Pattern Friction Sets with Spot Bolting of Rebar, Category C: Pattern Friction Sets with Pattern Rebar Bolts and Category D: Cablebolting, Shotcrete, Spiling, Timber Sets or Underhand Cut and Fill. Category A is considered “Unsupported” with an average Factor of Safety less than 1.2. Categories B, C and D are considered “Supported” with average Factors of Safety greater than 1.2. All categories are compared the original Critical Span Design Curve presented by Lang (1994). However, only Category A can be accurately compared to the original Critical Span Design Curve as it is “Unsupported” as well. Category A yields good results, however, Categories B, C and D do not, but still demonstrate that spans can remain stable at lower RMR76 values. Design of underground man-entry type excavations in North America relies heavily upon empirical analysis. This design requires a higher Factor of Safety than other non-man entry type excavations. A comparison of the calculated ½ span failure Factor of Safety between all the categories is also presented. The contribution this research provides to the mining industry is the "Unsupported" Weak Rock Updated Span Design Curve and awareness pertaining to the potentially detrimental effects of using resin grounted rebar in weak rock masses and the false sense of security that the use of resin grouted rebar may instill. It is also shown that spans in the “Unstable” zone of the new “Unsupported” Weak Rock Updated Span Design Curve can possibly be stabilized if detailed engineering design is applied to obtain “Supported” status.

This thesis presents ground control best practices in weak rock environments including an augmentation to the existing Span Design curve by adding 463 case histories of RMR76 values ranging from 25 to 60. A Neural Network analysis of this data has been added and compared to the existing Span Design data of 292 case histories. Ground support is almost always used in weak rock environments, though the type of support used can vary widely. The development of the weak rock augmented Span Design Curve has also been calibrated to four different support categories; Category A: Pattern Friction Sets, Category B: Pattern Friction Sets with Spot Bolting of Rebar, Category C: Pattern Friction Sets with Pattern Rebar Bolts and Category D: Cablebolting, Shotcrete, Spiling, Timber Sets or Underhand Cut and Fill. Category A is considered “Unsupported” with an average Factor of Safety less than 1.2. Categories B, C and D are considered “Supported” with average Factors of Safety greater than 1.2. All categories are compared the original Critical Span Design Curve presented by Lang (1994). However, only Category A can be accurately compared to the original Critical Span Design Curve as it is “Unsupported” as well. Category A yields good results, however, Categories B, C and D do not, but still demonstrate that spans can remain stable at lower RMR76 values. Design of underground man-entry type excavations in North America relies heavily upon empirical analysis. This design requires a higher Factor of Safety than other non-man entry type excavations. A comparison of the calculated ½ span failure Factor of Safety between all the categories is also presented. The contribution this research provides to the mining industry is the "Unsupported" Weak Rock Updated Span Design Curve and awareness pertaining to the potentially detrimental effects of using resin grounted rebar in weak rock masses and the false sense of security that the use of resin grouted rebar may instill. It is also shown that spans in the “Unstable” zone of the new “Unsupported” Weak Rock Updated Span Design Curve can possibly be stabilized if detailed engineering design is applied to obtain “Supported” status.

This thesis presents ground control best practices in weak rock environments including an augmentation to the existing Span Design curve by adding 463 case histories of RMR76 values ranging from 25 to 60. A Neural Network analysis of this data has been added and compared to the existing Span Design data of 292 case histories. Ground support is almost always used in weak rock environments, though the type of support used can vary widely. The development of the weak rock augmented Span Design Curve has also been calibrated to four different support categories; Category A: Pattern Friction Sets, Category B: Pattern Friction Sets with Spot Bolting of Rebar, Category C: Pattern Friction Sets with Pattern Rebar Bolts and Category D: Cablebolting, Shotcrete, Spiling, Timber Sets or Underhand Cut and Fill. Category A is considered “Unsupported” with an average Factor of Safety less than 1.2. Categories B, C and D are considered “Supported” with average Factors of Safety greater than 1.2. All categories are compared the original Critical Span Design Curve presented by Lang (1994). However, only Category A can be accurately compared to the original Critical Span Design Curve as it is “Unsupported” as well. Category A yields good results, however, Categories B, C and D do not, but still demonstrate that spans can remain stable at lower RMR76 values. Design of underground man-entry type excavations in North America relies heavily upon empirical analysis. This design requires a higher Factor of Safety than other non-man entry type excavations. A comparison of the calculated ½ span failure Factor of Safety between all the categories is also presented. The contribution this research provides to the mining industry is the "Unsupported" Weak Rock Updated Span Design Curve and awareness pertaining to the potentially detrimental effects of using resin grounted rebar in weak rock masses and the false sense of security that the use of resin grouted rebar may instill. It is also shown that spans in the “Unstable” zone of the new “Unsupported” Weak Rock Updated Span Design Curve can possibly be stabilized if detailed engineering design is applied to obtain “Supported” status. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

Este trabalho apresenta uma revisão bibliográfica sobre procedimentos de estudos sobre escorregamento, com enfoque para as metodologias de previsão a partir da combinação de conhecimentos de modelagem hidrológica e análise determinística tendo como base a avaliação do fator de segurança 3D. Foi desenvolvido um conjunto de procedimentos que permitam a previsão de escorregamentos em escalas maiores que 1:10.000 e estes foram aplicados em oito áreas na cidade de Campos do Jordão (SP). Os resultados obtidos para estas áreas são bastante promissores e refletiram as condições geológicas, geotécnicas e hidrogeológicas de cada área. / This work presents a review of procedures for landslides studies, with focus on the methodologies of forecasting from the combination of knowledge of hydrological modeling and analysis based on deterministic evaluation of the 3D factor of safety. It was developed a set of procedures for the prediction of landslides on scales larger than 1:10,000, and these were applied in eight areas in the city of Campos do Jordão (SP). The results for these areas are very promising and reflected the geological, geotechnical and hydrogeological conditions in each area.

Este trabalho apresenta uma revisão bibliográfica sobre procedimentos de estudos sobre escorregamento, com enfoque para as metodologias de previsão a partir da combinação de conhecimentos de modelagem hidrológica e análise determinística tendo como base a avaliação do fator de segurança 3D. Foi desenvolvido um conjunto de procedimentos que permitam a previsão de escorregamentos em escalas maiores que 1:10.000 e estes foram aplicados em oito áreas na cidade de Campos do Jordão (SP). Os resultados obtidos para estas áreas são bastante promissores e refletiram as condições geológicas, geotécnicas e hidrogeológicas de cada área. / This work presents a review of procedures for landslides studies, with focus on the methodologies of forecasting from the combination of knowledge of hydrological modeling and analysis based on deterministic evaluation of the 3D factor of safety. It was developed a set of procedures for the prediction of landslides on scales larger than 1:10,000, and these were applied in eight areas in the city of Campos do Jordão (SP). The results for these areas are very promising and reflected the geological, geotechnical and hydrogeological conditions in each area.

Safety of dams can be evaluated based on the risk analysis methodologies that accounts for estimation of the risks associated to the dam-reservoir system. For this purpose it is important to estimate the probability of load events and probability of failure for several failure modes. The following thesis emphasises on estimation of the probability of one specific failure mode, i.e. “sliding failure” for a concrete gravity dam. The main idea behind this thesis was to analyse the estimation of the probability of sliding failure of an existing dam by obtaining the relationships among the different load events, factors of safety associated to those events and the probability of failure estimated using numerical simulation techniques together with different reliability methods. The analysed dam is taken from theme C of the eleventh ICOLD Benchmark workshop on numerical analysis of dams. The thesis covers the methodology for estimating the probability of failure of a given concrete gravity dam with five water levels, considering the sliding failure mode along the dam-foundation interface along with the estimation of factors of safety for each water level and with two different drainage conditions. First order second moment Taylor’s Series Approximation is being used as Level 2 reliability method and Monte Carlo simulation as Level 3 reliability method to estimate the probability of failure against sliding of the dam. Conclusions are drawn in the end by comparing the results obtained from factor of safety estimation and probability of failure for each water level and drainage condition, followed by suggestions for further research in the context of sliding stability of concrete dams.

Σκοπός της παρούσας Διατριβής Ειδίκευσης είναι η ανάλυση, η παρουσίαση και η αξιολόγηση των γεωτεχνικών συνθηκών της πόλης των Πατρών, σε σχέση με την εκδήλωση του φαινόμενου της ρευστοποίησης και τις συνθήκες γεωλογικής καταλληλότητας για τις προς δόμηση περιοχές. Στα πλαίσια της διατριβής πραγματοποιήθηκαν γεωτεχνικές έρευνες για είκοσι πέντε (25) γεωτρήσεις που έχουν διανοιχθεί κατά μήκος της πόλης των Πατρών, και αξιολογήθηκαν τα αποτελέσματα των επί τόπου και των εργαστηριακών δοκιμών. Με τη βοήθεια του λογισμικού Petal υπολογίστηκε ο συντελεστής ασφάλειας για ρευστοποίηση σε κάθε γεώτρηση και συντάχθηκαν χάρτες ζωνών επικινδυνότητας για την πόλη των Πατρών. Η έρευνα αυτή πραγματοποιήθηκε για δύο σεισμικά γεγονότα. Για το σεισμό των Πατρών το 1993 με μέγεθος 5.4 Richter και το σεισμό του Αιγίου το 1995 με μέγεθος 6.2 Richter. / The aim of this MSc Project is the presentation, the analysis and the assessment of the geotechnical conditions in city of Patras, Western Greece, for liquefaction phenomenon and geological suitability for construction purposes. In this project were done geotechnical surveys for twenty-five (25) boreholes in area of Patras, and assessment insitu and laboratory tests. Using Petal program we can estimate the factor of safety against liquefaction. The data used to perform mapping, in some zones of liquefaction risk. The survey based on seismic facts. The first one was the earthquake in 1993 in city of Patras with magnitude 5.4 Richter and the second one was the earthquake in city of Aigio in 1995 with magnitude 6.2 Richter.

Slope stability assessments are classical problems for geotechnical engineers. The predictions of slope stability in soil or rock masses play an important role when designing for dams, roads, tunnels, excavations, open pit mines and other engineering structures. Stability charts continue to be used by engineers as preliminary design tools and by educators for training purposes. However, the majority of the existing chart solutions assume the slope problem is semi-infinite (plane-strain) in length. It is commonly believed that this assumption is conservative for design, but non-conservative when a back-analysis is performed. In order to obtain a more economical design or more precise parameters from a back-analysis, it is therefore important to quantify three dimensional boundary effects on slope stability. A significant aim of this research is to look more closely at the effect of three dimensions when predicting slope stability. In engineering practice, the limit equilibrium method (LEM) is the most popular approach for estimating the slope stability. It is well known that the solution obtained from the limit equilibrium method is not rigorous, because neither static nor kinematic admissibility conditions are satisfied. In addition, assumptions are made regarding inter slice forces for a two dimensional case and inter-column forces for a three dimensional case in order to find a solution. Therefore, a number of more theoretically rigorous numerical methods have been used in this research when studying 2D and 3D slope problems. In this thesis, the results of a comprehensive numerical study into the failure mechanisms of soil and rock slopes are presented. Consideration is given to the wide range of parameters that influence slope stability. The aim of this research is to better understand slope failure mechanisms and to develop rigorous stability solutions that can be used by design engineers. The study is unique in that two distinctly different numerical methods have been used in tandem to determine the ultimate stability of slopes, namely the upper and lower bound theorems of limit analysis and the displacement finite element method. The limit equilibrium method is also employed for comparison purposes. A comparison of the results from each technique provides an opportunity to validate the findings and gives a rigorous evaluation of slope stability.

The McTronX research group at the North–West University designs and develops Active Magnetic Bearings (AMBs). The group’s focus shifted to the design and development of AMB supported drive systems. This includes the electromagnetic and mechanical design of the electric machine, AMBs, auxiliary bearings as well as the development of the control system. The research group is currently developing an AMB supported high speed Induction Machine (IM) drive system that will facilitate tests in order to verify the design capability of the group. The research presented in this thesis describes the mechanical design and manufacturing of a high speed IM rotor section. The design includes; selecting the IM rotor topology, material selection, detail stress analysis and selecting appropriate manufacturing and assembly procedures. A comprehensive literature study identifies six main design considerations during the mechanical design of a high speed IM rotor section. These considerations include; magnetic core selection, rotor cage design, shaft design, shaft/magnetic core connection, stress due to operation at elevated temperatures and design for manufacture and assemble (DFMA). A critical overview of the literature leads to some design decisions being made and is used as a starting point for the detail design. The design choices include using a laminated cage rotor with a shrink fit for the shaft/magnetic core connection. Throughout the detail design an iterative process was followed incorporating both electromagnetic and mechanical considerations to deliver a good design solution. The first step of the iterative design process was, roughly calculating the material strengths required for first iteration material selection followed by more detailed interference fit calculations. From the detail stress analysis it became apparent that the stress in the IM rotor section cannot be calculated accurately using analytical methods. Consequently, a systematically verified and validated Finite Element Analysis (FEA) model was used to calculate the interferences required for each component. The detail stress analysis of the assembly also determined the allowable manufacturing dimensional tolerances. From the detail stress analysis it was found that the available lamination and squirrel cage material strengths were inadequate for the design speed specification of 27,000 r/min. The analysis showed that a maximum operating speed of 19,000 r/min can be achieved while complying with the minimum factor of safety (FOS) of 2. Each component was manufactured to the prescribed dimensional tolerances and the IM rotor section was assembled. With the failure of the first assembly process, machine experts were consulted and a revised process was implemented. The revised process entailed manufacturing five small lamination stacks and assembling the stack and squirrel cage afterwards. The end ring/conductive bar connection utilises interference fits due to the fact that the materials could not be welded. The process was successful and the IM rotor section was shrink fitted onto the shaft. However, after final machining of the rotor’s outer diameter (OD), inspections revealed axial displacement of the end rings and a revised FEA was implemented to simulate the effect. The results indicated a minimum FOS 0.6 at very small sections and with further analytical investigation it was shown that the minimum FOS was reduced to only 1.34. Although the calculations indicated the FOS was below the minimum prescribed FOS ? 2, the rotor spin tests were scheduled to continue as planned. The main reasons being that the lowest FOS is at very small areas and is located at non critical structural positions. The fact that the rotor speed was incrementally increased and multiple parameters were monitored, which could detect early signs of failure, further supported the decision. In testing the rotor was successfully spun up to 19,000 r/min and 27 rotor delevitation test were conducted at speeds of up to 10,000 r/min. After continuous testing a secondary rotor inspection was conducted and no visible changes could be detected. The lessons learnt leads to mechanical design and manufacturing recommendations and the research required to realise a 27,000 r/min rotor design. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.

The McTronX research group at the North–West University designs and develops Active Magnetic Bearings (AMBs). The group’s focus shifted to the design and development of AMB supported drive systems. This includes the electromagnetic and mechanical design of the electric machine, AMBs, auxiliary bearings as well as the development of the control system. The research group is currently developing an AMB supported high speed Induction Machine (IM) drive system that will facilitate tests in order to verify the design capability of the group. The research presented in this thesis describes the mechanical design and manufacturing of a high speed IM rotor section. The design includes; selecting the IM rotor topology, material selection, detail stress analysis and selecting appropriate manufacturing and assembly procedures. A comprehensive literature study identifies six main design considerations during the mechanical design of a high speed IM rotor section. These considerations include; magnetic core selection, rotor cage design, shaft design, shaft/magnetic core connection, stress due to operation at elevated temperatures and design for manufacture and assemble (DFMA). A critical overview of the literature leads to some design decisions being made and is used as a starting point for the detail design. The design choices include using a laminated cage rotor with a shrink fit for the shaft/magnetic core connection. Throughout the detail design an iterative process was followed incorporating both electromagnetic and mechanical considerations to deliver a good design solution. The first step of the iterative design process was, roughly calculating the material strengths required for first iteration material selection followed by more detailed interference fit calculations. From the detail stress analysis it became apparent that the stress in the IM rotor section cannot be calculated accurately using analytical methods. Consequently, a systematically verified and validated Finite Element Analysis (FEA) model was used to calculate the interferences required for each component. The detail stress analysis of the assembly also determined the allowable manufacturing dimensional tolerances. From the detail stress analysis it was found that the available lamination and squirrel cage material strengths were inadequate for the design speed specification of 27,000 r/min. The analysis showed that a maximum operating speed of 19,000 r/min can be achieved while complying with the minimum factor of safety (FOS) of 2. Each component was manufactured to the prescribed dimensional tolerances and the IM rotor section was assembled. With the failure of the first assembly process, machine experts were consulted and a revised process was implemented. The revised process entailed manufacturing five small lamination stacks and assembling the stack and squirrel cage afterwards. The end ring/conductive bar connection utilises interference fits due to the fact that the materials could not be welded. The process was successful and the IM rotor section was shrink fitted onto the shaft. However, after final machining of the rotor’s outer diameter (OD), inspections revealed axial displacement of the end rings and a revised FEA was implemented to simulate the effect. The results indicated a minimum FOS 0.6 at very small sections and with further analytical investigation it was shown that the minimum FOS was reduced to only 1.34. Although the calculations indicated the FOS was below the minimum prescribed FOS ? 2, the rotor spin tests were scheduled to continue as planned. The main reasons being that the lowest FOS is at very small areas and is located at non critical structural positions. The fact that the rotor speed was incrementally increased and multiple parameters were monitored, which could detect early signs of failure, further supported the decision. In testing the rotor was successfully spun up to 19,000 r/min and 27 rotor delevitation test were conducted at speeds of up to 10,000 r/min. After continuous testing a secondary rotor inspection was conducted and no visible changes could be detected. The lessons learnt leads to mechanical design and manufacturing recommendations and the research required to realise a 27,000 r/min rotor design. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.