As hard rock mining progresses into higher stress mining conditions through either late stage extraction or mining at depth, the rock mass is driven not just to the peak strength, but often well into the post-peak until complete ‘failure’ occurs and easier mining conditions become evident. Limited research has been accomplished in identifying the transition of the rock mass and its behaviour into the post-peak and this research investigates this behaviour in detail. As the rock mass progressively fails, fractures are initiated through intact rock and extension and shear failure of these and pre-existing features occurs. Associated with this failure are microseismic events, which can be used to give an indication of the strength state of the rock mass. Based on an analogy to laboratory testing of intact rock and measurement of acoustic emissions, the microseismicity can be used to identify, fracture initiation, coalescence of fractures (yield), localization (peak-strength), accumulation of damage (post-peak) and ultimate failure (residual strength) leading to aseismic behaviour. The case studies presented in this thesis provide an opportunity to examine and analyse rock mass failure into the post-peak, through the regional and confined failures at the Williams and the Golden Giant mines, both in the Hemlo camp in Northern Ontario, Canada. At the Williams mine, the progressive failure of a sill pillar region into the post-peak was analysed; relating the seismic event density, combined with numerical modelling and a spatial and temporal examination of the principal components analysis (PCA), to characterize the extent, trend and state of the yielding zone, which formed a macrofracture shear structure. Observations of conventional displacement instrumentation, indicates regional dilation or shear of the rock mass occurs at or prior to the point of ‘disassociation’ (breakdown of stable PCA trends) when approaching the residual strength. At the Golden Giant mine, the complete process from initiation to aseismic behaviour is monitored in a highly stressed and confined pendent pillar. The PCA technique, numerical modelling and focal mechanism studies are used to define significant stages of the failure process, in which a similar macrofracture structure was formed. Temporal observations of key source parameters show significant changes prior to and at the point of coalescence and localization.

As hard rock mining progresses into higher stress mining conditions through either late stage extraction or mining at depth, the rock mass is driven not just to the peak strength, but often well into the post-peak until complete ‘failure’ occurs and easier mining conditions become evident. Limited research has been accomplished in identifying the transition of the rock mass and its behaviour into the post-peak and this research investigates this behaviour in detail. As the rock mass progressively fails, fractures are initiated through intact rock and extension and shear failure of these and pre-existing features occurs. Associated with this failure are microseismic events, which can be used to give an indication of the strength state of the rock mass. Based on an analogy to laboratory testing of intact rock and measurement of acoustic emissions, the microseismicity can be used to identify, fracture initiation, coalescence of fractures (yield), localization (peak-strength), accumulation of damage (post-peak) and ultimate failure (residual strength) leading to aseismic behaviour. The case studies presented in this thesis provide an opportunity to examine and analyse rock mass failure into the post-peak, through the regional and confined failures at the Williams and the Golden Giant mines, both in the Hemlo camp in Northern Ontario, Canada. At the Williams mine, the progressive failure of a sill pillar region into the post-peak was analysed; relating the seismic event density, combined with numerical modelling and a spatial and temporal examination of the principal components analysis (PCA), to characterize the extent, trend and state of the yielding zone, which formed a macrofracture shear structure. Observations of conventional displacement instrumentation, indicates regional dilation or shear of the rock mass occurs at or prior to the point of ‘disassociation’ (breakdown of stable PCA trends) when approaching the residual strength. At the Golden Giant mine, the complete process from initiation to aseismic behaviour is monitored in a highly stressed and confined pendent pillar. The PCA technique, numerical modelling and focal mechanism studies are used to define significant stages of the failure process, in which a similar macrofracture structure was formed. Temporal observations of key source parameters show significant changes prior to and at the point of coalescence and localization.

Submitted by ALEXANDRE CONCEICAO (alemgc@gmail.com) on 2017-09-14T01:37:47Z No. of bitstreams: 1 dissertacao-alexandre-conceicao.pdf: 2127579 bytes, checksum: 809d5da780c4b1ae1c60b356b8ef1fbf (MD5) / Approved for entry into archive by Thais Oliveira (thais.oliveira@fgv.br) on 2017-09-14T17:48:55Z (GMT) No. of bitstreams: 1 dissertacao-alexandre-conceicao.pdf: 2127579 bytes, checksum: 809d5da780c4b1ae1c60b356b8ef1fbf (MD5) / Made available in DSpace on 2017-09-15T12:16:46Z (GMT). No. of bitstreams: 1 dissertacao-alexandre-conceicao.pdf: 2127579 bytes, checksum: 809d5da780c4b1ae1c60b356b8ef1fbf (MD5) Previous issue date: 2017-08-23 / Using dynamic factor models, one can analyse stocastic processes having multiple dimensions, that being the case on financial markets when considering the series formed by the stock prices. By using the model predictions it is possible to create trading strategies and measure their performance. With the closing prices of the stocks belonging to the IBX100 index from 2010 till 2016, the model parameters were estimated and trading strategies were proposed. The performance indicators of some strategies were superior than those of the IBOVESPA index on the given period of time, offering anualized returns of 27% and a 48% maximum drawdawn against 1.12% anualized return and 48% maximum drawdawn on the IBOVESPA. Therefore, those models are capable of capturing the price dynamic in such a way that their predictions can be used to create trading strategies having a performance higher than that of the IBOVESPA index. / O uso de modelos de fatores dinâmicos permite analisar processos estocásticos com grande número de dimensões, sendo exatamente esse o caso do mercado financeiro quando se consideram as séries formadas pelos preços de ações. Ao se utilizar as previsões feitas pelos modelos, é possível criar estratégias de trading cuja performance pode ser aferida. De posse dos preços de fechamento de ativos pertencentes ao IBX100 no período de 2010 até 2016, os parâmetros do modelo foram estimados e estratégias de trading foram propostas. Os indicadores de performance de algumas das estratégias superaram aqueles do índice IBOVESPA no período estudado, oferecendo retorno anualizado de até 27% e máximo drawdawn de 21%, contra um retorno de 1.12% e max drawdawn de 48% do IBOVESPA. Portanto, esses modelos são capazes de capturar a dinâmica dos preços de ações na medida em que suas previsões podem ser utilizadas para criar estratégias de trading com performance superior à do Índice IBOVESPA.