Ground-Penetrating Radar (GPR) is a popular non-destructive geophysical technique with a wide range of diverse applications. Civil engineering, hydrogeophysics, forensic, glacier geology, human detection and borehole geology are some of the fields in which GPR has been applied with successful or promising results. One of the most mainstream applications of GPR is landmine detection. A lot of methods have been suggested over the years to assist the landmine detection issue. Metal detectors, trained rats or dogs, chemical methods and electrical resistivity tomography are –amongst others– some of the suggested techniques. The non-destructive nature of GPR makes it an attractive choice for a problem such as demining in which contact to the ground is not allowed. The main advantage of GPR is its ability to detect both metallic and non-metallic targets. Furthermore, GPR can provide an insight regarding the nature of the target (e.g. size, burial depth, type). From the above, it is evident that GPR can potentially reduce the false alarms emerging from small metallic objects (e.g. bullets, wires, etc.) usually encountered in battle-fields and industrialised areas. Combining the robustness of the metal detector with the resolution of GPR results in a reliable and efficient detection framework which has been successfully applied in Cambodia and Afghanistan. Despite the promising, and in some cases impressive results, aspects of GPR can be further improved in an effort to optimise GPR’s performance and decrease its limitations. The validation of a GPR system is usually achieved through the so called Receiver Operation Characteristics (ROC) which depicts the probability of detection with respect to the false alarm rate. ROC is a highly nonlinear function which is sensitive to the environment as well as to the antenna unit. Landmines are typically small objects, often less than 10 cm diameter, which are shallow buried, usually in less than 10 cm depth, and sometimes almost exposed. In order for the landmines to be resolved, high frequency antennas are essential. The latter are sensitive to soil’s inhomogeneities, rough surface, water puddles, vegetation and so on. Apart from that, the near field nature of the problem makes the antenna unit part of the medium which contributes to the unwanted clutter. The above, outlines the multi-parametric nature of the problem for which no straightforward approach has yet to be proposed. Numerical modelling is a practical and solid approach to understand the physical behaviour of a system. In the case of GPR for landmine detection, numerical modelling can be a practical tool for designing and optimising antennas in synthetic but nonetheless realistic conditions. Apart from that, evaluation of a processing method only to a specific environment is not a robust approach and does not provide any evidence for its wider inclusivity and limitations. However, evaluation in different conditions can become costly and unpractical. Numerical modelling can tackle this problem by providing data for a wide range of scenarios. An extensive database of simulated responses, apart from being a practical testbed, can be also employed as a training set for machine learning. A multi-variable problem like demining, in order to be addressed using machine learning, requires a large amount of data. These must equally include all possible different scenarios i.e. different landmines, in different media with stochastically varied properties and topography. Additionally, different heights of the antenna and different depths of the landmines must also be examined. Numerical modelling seems to be a practical approach to achieve an equally distributed and coherent dataset like the one briefly described above. Numerical modelling of GPR for landmine detection has been applied in the past using generic antennas in simplified and clinical scenarios. This approach can be used in an educational context just to provide a rough estimation of GPR’s performance. In the present thesis a realistic numerical scheme is suggested in which, simplifications are kept to a minimum. The numerical solver, employed in the suggested numerical scheme, is the Finite- Difference Time-Domain (FDTD) method. Both the dispersive properties and the Absorbing Boundary Condition (ABC) are implemented through novel and accurate techniques. In particular, a novel method which implements an inclusive susceptibility function is suggested and it is shown that surpasses the performance of the previous approaches while retaining their computational efficiency. Furthermore, Perfectly Matched Layer (PML) and more specifically Convolutional Perfectly Matched Layer (CPML) is implemented through a novel time-synchronised scheme which it is proven to be more accurate compared to the traditional CPML with no additional computational requirements. An accurate numerical solver, although essential, is not the only requirement for a realistic numerical framework. Accurate implementation of the geometry and the dielectric properties of the simulated model is highly important, especially when it comes to high-frequency near-field scenarios such as GPR for landmine detection. In the suggested numerical scheme, both the soil’s properties as well as the rough surface are simulated using fractal correlated noise. It is shown, that fractals can sufficiently represent Earth’s topography and give rise to semi-variograms often encountered in real soils. Regarding the dielectric properties of the soils, a semi-analytic function is employed which relates soil’s dielectric properties to its sand fraction, clay fraction, sand density, bulk density and water volumetric fraction. Subsequently, the semi-analytic function is approximated using a Debye function that can be easily implemented to FDTD. Vegetation is also implemented to the model using a novel method which simulates the geometry of vegetation through a stochastic process. The experimentally-derived dielectric properties of vegetation are approximated –similarly to soil’s dielectric properties– with a Debye expansion. The antenna units tested in the numerical scheme are two bow-tie antennas based on commercially available transducers. Regarding the targets, three landmines are chosen, namely, PMN, PMA-1 and TS-50. Dummy landmines are used in order to obtain their geometrical characteristics and comparison between measured and numerically evaluated traces are used to tune the dielectric properties of the modelled landmines. Lastly, water puddles are realistically implemented in the model in an effort to realistically simulate high-saturated scenarios. The proposed numerical scheme has been employed in order to test and evaluate widely used post-processing methods. The results clearly illustrate that post-processing methods are sensitive to the antenna unit as well as the medium. This highlights the importance of an accurate numerical scheme as a testbed for evaluating different GPR systems and post-processing approaches in wide range of scenarios. Using an equivalent 2D numerical scheme –restricted to 2D due to computational constrains– preliminary results are given regarding the effectiveness of Artificial Neural Network (ANN) subject to an adequate and equally distributed database. The results are promising, showing that ANN can be successfully employed for detection as well as classification using only a single trace as input. A basic requirement to do so is a representative training set. This can be synthetically generated using a realistic numerical framework. The above, provide solid arguments for further expanding the proposed machine learning scheme to the more computationally demanding 3D case.

Due to the unbonded nature of tendons to the slab within Unbonded Post Tensioned (UPT) concrete structures, tendon stress relaxation under heating affects all regions of the slab spanned by the tendon; not just in the locality of the fire. The numerical modelling of bonded and unbonded post tensioned concrete structures in fire has been performed to some degree, notably by Bailey and Ellobody. The consideration of elevated temperature creep to the relaxation of tendon prestress however, has not been considered. This thesis attempts to incorporate a uniaxial creep strain rate function of stress and temperature into the commercial FE software package Abaqus, compatible for use within the in-built multiaxial metal plasticity constitutive framework. What follows is a validation study of the Harmathy’s uniaxial creep strain accumulation function via the modelling of stress relaxation in isolated, tensioned and heated prestressing steel tendons, against experimental data. From here, UPT concrete slab models are analysed whilst exposed to a standard fire temperature-time curve and subsequently allowed to cool. Tendon prestress relaxation and resulting UPT concrete slab deflection is compared, where tendon creep is explicitly modelled, as opposed to implicitly covered by Eurocode 2 determined temperature dependent stress-strain curves. Following this, a large scale continuous one-way spanning UPT concrete structural model is developed to consider global structural behaviour resulting from localised fire, where realistic boundary conditions such as beam rotation and deflection are permitted. The ignorance of explicit elevated temperature creep consideration, in prestressing steel tendons, is commonly justified through the implicit accountability stated within Eurocode 2 temperature dependent stress-strain curves. This however is not completely true; Eurocode 2 states implicit accountability only holds should the tendon be heating at a rate within the bounds of 2⁰C/min to 50⁰C/min. Where only heating of a UPT concrete slab is considered, evidence from this thesis suggests Eurocode 2 determined stress-strain curves can implicitly account for accumulated creep strain up to limited temperatures. Prestressing steel tendons are however embedded within a concrete slab through which thermal gradients build up during fire. This means heat transfer can continue to the tendon, increasing its temperature postfire at an ever decreasing rate until it reaches its peak. Should post-fire cooling behaviour not be considered, continued tendon heating and subsequent creep strain accumulation will be ignored. Further, during the transition from heating to cooling within the tendon, it will be exposed to elevated temperatures with a rate of change below 2⁰C/min, whereby Eurocode 2, as stated cannot implicitly account for creep. It is shown, a significant degree of subsequent relaxation of prestress, UPT concrete slab deflection and concrete damage in hogging can occur during this phase of postfire behaviour, where the tendon temperature peaks during its transition from heating to cooling. In order to justify non consideration of creep, it should be shown tendon temperature will remain suitably low throughout the entire heating-cooling regime to which the UPT concrete slab is exposed. This must be achieved through adequate specification of minimum concrete cover to tendons to limit tendon temperature exposure for a given parametric fire curve duration, including the potential continued rise post-fire. Evidence within this thesis identifies 350⁰C as a critical temperature whereby the explicit consideration of tendon creep does not significantly increase predicted prestress relaxation and subsequent UPT concrete slab deformation, compared to implicit creep consideration from Eurocode 2. The manufacturing standard to which prestressing steel tendon strands are produced has been shown experimentally by Gales to significantly influence their susceptibility to elevated temperature creep. This is reflected by Gales determining differing creep parameters as a function of stress for incorporation in Harmathy’s uniaxial creep strain function. Modelled prestress relaxation of isolated, tensioned and heated tendons within this thesis is therefore significantly reduced when tendons are manufactured to a yield stress of 1860MPa according to the BS 5896 standard, as opposed to the ASTM A416 standard. As a result Eurocode 2 determined stress-strain curves implicitly account for accumulated creep strain during heating, at 10⁰C per minute, up to approximately 400⁰C for grade 1860 ASTM A416 manufactured tendons and 500⁰C for grade 1860 BS 5896 standard tendons. The aforementioned critical temperature of 350⁰C does not in actuality apply to necessary explicit creep consideration for UPT concrete slabs modelled with grade 1860 BS 5896 standard tendons. This temperature however remains a design temperature limit, owing to the potential onset of microstructural recrystallization beyond 400⁰C and the associated degradation of mechanical properties that coincides. The reasons for such differing elevated temperature creep and stress relaxation behaviour between the two manufacturing standards of prestressing steel wires and strands has been postulated within this thesis to be due to differing chemical compositions. This relates specifically to large relative differences of phosphorus and sulphur found in wires manufactures to each standard as tested by Gales.

The behaviour of concrete structures subjected to high impulsive loading such as blast involves complex responses at the constituent material as well as local to global structural levels. To fully describe the processes involved, detailed numerical simulation is generally required and it is in fact commonly employed nowadays in this field of investigations. However, the demands on a rigorous computational model with the capability to represent different regimes of responses throughout the entire process, namely the stress wave stage under the immediate impulsive (blast) loading, the development of local composite mechanism (such as shear), and finally the global bending / residual structural state, have not been established nor thoroughly investigated in the literature. This thesis aims to fill in this gap and develop an effective and efficient modelling framework for reinforced concrete (RC) structures under impulsive loading, with a particular focus on the analysis of complex dynamic shear mechanisms and the residual structural capacities. This thesis uses a benchmark RC slab as a testbed to firstly examine the validity of commonly applied finite element setup and typical material models for the analysis of the structural response into the global deformation phase and the residual state. This is followed by a detailed scrutiny of the demands on the concrete material model in terms of preserving a realistic representation of the tension/shear behaviour and the significance of such features in simulating realistically the structural response in a reinforced concrete environment. Deficiencies of a widely used concrete material model, namely the Karagozian and Case concrete (KCC) model, in this respect are investigated and a modification scheme to the relevant aspects of the material model is proposed. The modification is demonstrated to result in satisfactory improvement in terms of ensuring more robust simulation of reinforced concrete response to blast loading. To deal with the inevitable modelling uncertainties in the part of concrete surrounding reinforcing bars in a numerical model, an equivalent transitional layer model is proposed for use in finite element modelling of RC structures subjected to impulsive loading. The main objectives of the equivalent transitional layer are to achieve a consist transfer of stress between rebar to concrete outside the transitional zone, and to maintain a realistic relative “sliding” displacement between the outer edge of the transitional layer and the rebar, while the inner edge of the transitional layer is perfectly bonded (with node-sharing) to the rebar. With appropriate descriptions of the softening and failure of the material for the transitional layer, the deformation profile and the strength can be reasonably represented in a consistent manner using the perfect-bond scheme which is commonly adopted in this field of applications. The transitional layer also incorporates features to ensure mesh-independent bond strength. Validation of proposed transitional layer model is carried out against results from RC pullout and beam experiments. The above modelling framework is subsequently employed to investigate the dynamic shear resistance of RC beam/slab under impulsive loading, recognising that the information on the dynamic shear strength in very scarce in the literature. The influence of loading rate on the change of shear span, which alters the shear resistance mechanism and generally results in an increase of the shear capacity, is discussed. The influence of the strain rate enhancement of the material strength on the dynamic shear capacity is also evaluated.

La calotte polaire du Groenland retient dans ses glaces une contribution potentielle au niveau des mers de 7,3 mètres. Alors que des changements importants sont observés à l'heure actuelle, réaliser des projections sur son état futur à l'échelle pluri-centennal est devenu une priorité. La modélisation numérique 3D est l'un des outils pour effectuer ces projections. Ce travail incorpore largement l'utilisation des carottages profonds du Groenland, qui rassemblent une grande part d'information sur les états passés. Ainsi, l'accent est ici mis sur les validités des reconstructions effectuant constamment des aller-retour entre observations et simulations. La robustesse de ces reconstructions et des projections futures est largement questionnée au travers de nombreuses expériences de sensibilité. La calibration du modèle de glace en utilisant des contraintes sur les informations de la dernière déglaciation permet de proposer des scénarios sur l'état de la calotte au cours du précédent interglaciaire, l'Eémien, potentiel analogue pour le climat futur. / The Greenland ice sheet represents a potential sea level rise contribution of 7.3 meters. When drastic changes are recently observed, multi-centennal futur projections are urgently needed. 3D numerical modelling is one of the tools to realize these projections. This work intensively incorporates the use of Greenland deep ice core drillings, which represent an important amount of information of past states of the ice sheet. The validity of the reconstructions are thus assured by constant back and forth between observations and simulations. Robustness of these reconstructions and of future projections are largely questionned through wide sensitivity experiments. The ice sheet model calibration is performed during the last deglaciation considering the numerous constraints during this period. Given that, scenarios of ice sheet states during the whole last climatic cycle, in particular during the last interglacial, the Eemian, potential analogue for a future climate.

Este trabalho aborda a influência da hidrodinâmica da Lagoa dos Patos (RS) no comportamento de variáveis indicadoras da qualidade da água, como o material em suspensão, o oxigênio dissolvido, os nutrientes inorgânicos dissolvidos e a clorofila-a. Adicionalmente, o trabalho apresenta uma avaliação do efeito do lançamento de efluentes na magnitude das concentrações destas variáveis e nas suas inter-relações. Para o desenvolvimento deste estudo aplicou-se o modelo numérico MOHID 2D, utilizado com êxito na gestão ambiental de regiões costeiras. Os resultados indicam que a Lagoa dos Patos é um corpo lagunar heterogêneo no qual sua hidrodinâmica é regida principalmente pela atuação dos ventos e da vazão fluvial. Esses fatores influenciam diretamente o comportamento das variáveis estudadas. A presença de efluentes altera significativamente a magnitude das concentrações dos nutrientes e da clorofila-a no ambiente, principalmente nas regiões próximas aos locais de lançamento. A modelagem numérica é uma importante ferramenta para a gestão ambiental de sistemas dinâmicos e que variáveis ecológicas são condicionadas pelas suas inter-relações e pela circulação do sistema. / This work assesses the influence of Patos Lagoon- RS hydrodynamics in the behavior of water quality indicator variables as like suspended material, dissolved oxygen, dissolved inorganic nutrients and chlorophyll-a. Also gives an assessment of the effect of effluent discharge in the magnitude of the concentrations of these variables and in their interrelationships. To develop this study we applied the numerical model MOHID 2D, successfully applied in environmental management of coastal areas. The results indicate that Patos Lagoon is a heterogeneous system in which its hydrodynamic is governed mainly by the action of wind and river flow, which directly influence the behavior of water quality variables. Furthermore, the presence of effluent significantly changes the magnitude of the nutrients and chlorophyll-a concentration, particularly in areas close to the sewage launch sites. We concluded that the numerical modeling is an important tool for the dynamics systems management and that ecological variables are not only conditioned by their interrelations, but also by system circulation.

Os processos morfodinâmicos em sistemas de desembocaduras estão relacionados a uma variedade de condições forçantes que criam condições hidrodinâmicas únicas. Correntes de maré, ondas e descarga fluvial, interagindo em diferentes níveis resultam em complexos padrões dinâmicos. O objetivo do presente trabalho é entender os processos que controlam a dinâmica da desembocadura do estuário do rio Itanhém, Alcobaça, BA. A dinâmica do ambiente foi analisada através de imagens de satélite LANDSAT5-TM e da aplicação de um modelo numérico. As imagens de satélite disponíveis, para os anos de 1987, 1990, 1996, 2007, 2008 e 2009, foram utilizadas para extrair os contornos da linha de costa que, juntamente com dados batimétricos constituíram as malhas para o desenvolvimento de uma série de experimentos numéricos. O modelo numérico utilizado foi o MIKE 21 FM. Foram utilizados três módulos: propagação de ondas, hidrodinâmico e de transporte de sedimento, com retroalimentação entre as mudanças morfológicas e a hidrodinâmica. A descrição dos processos observados pelas imagens de satélite, juntamente com os resultados dos experimentos numéricos mostraram que na região ocorreu acúmulo de sedimentos com consequente crescimento de um pontal a barlamar da desembocadura entre 1987 e 2007. Em 2007 o pontal atingiu seu tamanho máximo, e em função de um evento de alta energia, se rompeu ao norte, deixando dois canais. No período quando o canal era mais estreito, houve maior transporte pela deriva verificado pelo crescimento do banco. Já no período de canal mais largo, houve interrupção na deriva e o banco não cresceu. O mecanismo principal de transporte de sedimentos na área de estudo deve-se principalmente à incidência das ondas do quadrante nordeste, que gera uma corrente de deriva litorânea para sul. As ondas do quadrante sul e sudeste, mais energéticas, e que poderiam gerar deriva na direção oposta, são refratadas pela presença dos parcéis e da progradação da linha de costa em Caravelas, localizados a sudeste e sul da área de estudo. O novo canal formado pelo rompimento do pontal tornou-se o principal meio de fluxo das correntes. Este fluxo atua como uma barreira, interrompendo a deriva litorânea de sedimentos, aprisionando-os a barlamar e limitando o suprimento de sedimentos responsáveis pelo crescimento do banco arenoso ao sul. Nota-se que o tamanho e a largura do novo canal definem a quantidade de sedimentos que atravessa a desembocadura, controlando o crescimento deste banco. / The morphodynamic processes at inlet systems are related to a variety of forcing conditions that create unique hydrodynamic conditions. The interaction of tidal currents, wave conditions, and river discharge at different levels result in complex dynamic patterns. The present work aims to understand the processes that control the dynamics of the Itanhaém River, Alcobaça (BA). The system dynamics was analyzed through the combined application of LANDSAT5-TM satellite images, field measurements and numerical modelling. A set of satellite images (for 1987, 1990, 1996, 2007, 2008 and 2009) was used to extract the coastline contours which, combined with the bathymetric data, defined the grids for a series of numerical experiments. Three modules of the MIKE 21 FM model have been applied: wave propagation, hydrodynamic and sediment transport, including the feedback between the morphological changes and the hydrodynamics. The description of the processes observed through the satellite images and the results of the numerical experiments show that there is a spit growth driving the inlet southwards between 1987 and 2007. In 2007 the spit reached its maximum extent and a high wave energy event breached the spit leaving the system with two openings to the ocean. The sediment supply to the southern sandbar is controlled by the longshore drift, with its quantities being apparently controlled by the inlet width. The main mechanism of sediment transport in the study area is mainly due to the northeasterly waves, moving sediments southwards. The more energetic southerly waves, which could lead to transport in the opposite direction, are refracted due to the wide shelf and the presence of coral reefs in the region. The new inlet formed by the spit breach became the main flow channel. This flow interrupts part of the littoral drift, retaining sediment updrift and limiting the sediment supply downdrift. The size and width of the new inlet define the amount of sediment being bypassed, controlling the growth of the sandbar.

In rock constructions and mining it is important to know the current stress situation in the rock due to safety and construction reasons. Two of the widely used stress measurement methods are overcoring and hydraulic fracturing. Both methods are expensive, need new boreholes, and are complex and time consuming. The methods are also limited by the number of successfully achieved measurements series. An alternative method is therefore investigated by locally relieving stresses around the borehole wall using sawn slots. To determine the stresses in the rock, strain measurements will be done using optics and image processing of images taken before and after cutting of the slots. The images will be processed by a technique called Digital Image Correlation (DIC), a method where the pixels are fitted between the images by the greyscale. The thesis is roughly divided into three parts. The first part explains the basics of rock stresses and current stress measurement methods. The second part is a literature study of the theory behind optics and DIC. There is also a study about if it is possible to use optics from a smartphone and how it differs from a reference commonly used camera in DIC application. Last part consists of numerical calculations in 2D to investigate if there is a possibility to relieve the stress around the borehole walls by cutting slots. With the optics from a smartphone the borehole wall can be in focus on just a few millimeters distance. DIC is a well-developed method which has a good precision when being conducted right and with a good image quality. The combination of using a smartphone and DIC is, however, not fully investigated yet. Only one comparable study was found. It used a Sony tablet and measured the deformations instead of strains. However, that study showed that the measurement error was around 1% compared to the reference camera. When translating deformations into strains, it is most likely that the error will increase, because the error will also be affected from the difference in deformation before and after cutting the slots. The numerical part showed that it’s possible to relieve the stress at parts of the borehole walls for the investigated conditions. To fully relieve the stresses around the borehole wall, it is necessary to have two slots with a short c-c distance and relatively deep slots. In this case a c-c distance of 15 mm and slot depth of at least 25 mm are recommended. / Vid projekt inom berganläggningar och gruvor är det viktigt att känna till de rådande spänningar i berget i ett säkerhets- och konstruktionsperspektiv. I Sverige används framförallt två undersökningsmetoder - överborrning eller hydraulisk spräckning. Två metoder som dock är dyra och relativt få mätserier kan genomföras. En alternativ metod har därför undersökts där borrhålsväggen lokalt avlastas genom sågade slitsar. Töjningsmätning sker genom att fotografera borrhålsväggen innan och efter sågning av slitsarna. Därefter sker bildbehandling via Digital Image Correlation (DIC). En metod som jämför en pixels placerings förändring genom att matcha pixeln via gråskalan. Examensarbetet kan man säga är grovt indelat i tre delar. Den första delen innefattar teorin som handlar om bergspänningar samt nuvarande mätmetoder för att mäta bergsspänningar. Andra delen är en litteraturstudie som behandlar den bakomliggande teorin för optik och bildbehandling med DIC samt en kort undersökning om det är möjligt att använda den optiska tekniken som finns i en smartphone. Sista delen utgörs av numeriska modelleringar i 2D för att verifiera om det går att fullständigt avlasta ett borrhål genom sågade slitsar. Med optik som finns i en smartphone kan bergväggen vara i fokus på bara ett par millimeters avstånd. DIC i sig är en teknik som är så pass utvecklad att precisionen i mätningarna är väldigt god. Förutsatt att bildbehandling görs korrekt och bildkvalitén är god. Kombinationen med optik liknande den från smartphone och bildbehandling med DIC är dock inte fullständigt undersökt. Enbart en jämförbar studie har hittats där deformationsmätningar har gjort med hjälp av en Surfplatta från Sony. Denna undersökning visade att mätfelet mot en referenskamera är cirka 1%. Dock förstärks mätfelet vid töjningsmätningar. Förstärkningen beror dock även av deformationsskillnaden mellan innan och efter avlastning. Den numeriska delen har visat att det går att lokalt avlasta bergväggen fullständigt för det undersökta spänningsförhållandet. Dock krävs det att två slitsar sitter på ett litet c-c avstånd samt är relativt djupa. Två undersökta slitsuppsättningar har visat på fullständigt avlastning, samt ytterligare ett fall som skulle kunna vara användbart.

O impacto econômico da diluição não planejada está distribuído no aumento de custos diversos do processo, como carregamento, transporte, britagem e moagem, ocasionando um desperdício na capacidade total de processo. Esse trabalho tem como objetivo inicial quantificar a ocorrência de diluição não planejada existente no hangingwall de uma mina subterrânea de ouro com método Transversal Stope e recuperação de pilares com uso de enchimento cimentado. Posteriormente está o uso de modelagem numérica com o objetivo de reproduzir a ocorrência de diluição, além de proporcionar a verificação e otimização de diferentes geometrias para os stopes. A diluição pode ser atribuída tanto a forma de extração (desenho dos stopes, sequência, perfuração e desmonte), além de problemas geomecânicos (qualidade do maciço, cablebolts e estado tensional). Otimizações para reduzir a diluição não planejada requerem um entendimento de todos esses fatores que afetam direta e indiretamente o ingresso de material estéril do hangingwall nos stopes. Este trabalho tem como foco principal verificar a diluição proveniente de problemas geomecânicos e de desenho dos stopes. As ferramentas utilizadas para analisar e quantificar os fatores de diluição foram: escâner de cavidades (CMS - Cavity Monitoring System) e software 3D capaz de efetuar operações booleanas. A diluição no hangingwall foi quantificada por meio da metodologia do fator ELOS. Para reproduzir a diluição nos stopes foram utilizados modelos numéricos de elementos finitos sendo que cinco stopes primários foram selecionados e utilizados para calibração dos modelos. O volume da zona de relaxamento no hangingwall, produzido pelos modelos, apresentou uma boa correlação com o volume da diluição real, refletindo a realidade dos stopes produzidos na mina. Então, a partir dos modelos calibrados, foram produzidos novos modelos com diferentes geometrias de stopes onde foi possível observar diversas oportunidades de melhorias na redução da diluição do método, fazendose modificações no desenho dos stopes/galerias e nos cablebolts instalados no hangingwall. / The economic impact of unplanned dilution is distributed in an increase in many costs of the process, such as loading, transport, crushing and grinding, resulting in less overall process capability. This work has as main goal quantify the unplanned dilution in the hangingwall of an underground gold mine with pillar less Transversal Stopes method, using cemented rock fill. After, numerical modeling will be used in order to reproduce the occurrence of dilution, and provide verification and optimization of different geometries for stopes. Overbreak can be attributed to both the shape extraction (design of the stopes, sequence, drill and blast), and geotechnical problems (rock quality, cablebolts and tensional state). Efforts to reduce unplanned dilution require an understanding of all these factors that directly and indirectly affect the inflow of waste material from hangingwall to the open stopes. This work is mainly focused on checking the dilution from geomechanical problems and design of the stopes. The main tools used in the analysis of dilution factors were Cavity Monitoring System (CMS) and 3D software able to perform boolean operations. The dilution in the hanging wall was quantified by the ELOS methodology. To reproduce the dilution in the stopes, numerical finite element models were used and five primary stopes were selected as calibration models. The volume of the relaxation zone at the hanging wall, produced by the models, showed good correlation with the volume of actual dilution, reflecting the reality of stopes produced at the mine. Then, from the calibrated models were produced new models with different stopes geometries where we could see several opportunities for improvement in reducing the dilution of the method, making some modifications to the design of the stopes/galleries and in cablebolts of the hangingwall.

No Brasil há uma crescente demanda por projetos de edifícios em alvenaria estrutural, com a progressiva elevação do número de pavimentos, impondo a necessidade de aprimoramento dos modelos de cálculo. Uma questão pouco estudada é o comportamento da interseção de paredes sob carregamento vertical, fenômeno que influencia a distribuição das ações ao longo da altura do edifício. Alguns autores admitem a transferência de forças de uma parede para outra, desde que haja o intertravamento dos blocos ao longo das interfaces das paredes. Há pelo menos duas formas de considerar a interação no dimensionamento estrutural: durante a distribuição das ações verticais ou na consideração do enrijecimento da parede. Para verificar esta interação das paredes e investigar a taxa de transferência de força foram realizados ensaios em escala real no laboratório de estruturas da EESC-USP. Realizou-se a modelagem numérica via MEF dos painéis de alvenaria ensaiados, para comparação do comportamento. Estendeu-se esta modelagem a outros painéis de alvenaria, variando-se suas dimensões, para a determinação das taxas de transferência de forças entre paredes. / In Brazil there is an increasing demand for high rise structural masonry buildings design which imposes the necessity to refine design models. One of the phenomenon on which little interest has been directed is the behaviour of wall intersections under vertical load, a phenomenon that influences the distribution of forces along the height of the building. Some authors argue that there is a transfer of forces from one wall to another in as much as there exist interlocking between the blocks along the wall interface. There are at least two ways to consider the interaction of walls in the structural design: during the distribution of the vertical load or on considering the stiffening of the wall. In order to verify the interaction of wall and thus investigate the force transfer ratio, full-scale specimens were tested at the EESC-USP laboratory. The tested panels were also modelled numerically by the FEM in order to compare with results from laboratory tests. The propose numerical model was then extended to structural masonry panels of varying dimensions in order to determine the force transfer ratio between structural masonry walls.

O comportamento mecânico de vigas em alvenaria estrutural submetidas ao cisalhamento é abordado de forma aprofundada neste trabalho. São apresentados neste estudo um extensivo levantamento bibliográfico, o qual estabelece um panorama sobre o tema, um programa experimental com ensaios de caracterização do material alvenaria e de vigas em escala natural e um estudo numérico das vigas ensaiadas em laboratório. Na etapa de caracterização dos materiais o comportamento compósito da alvenaria é analisado por meio de prismas submetidos à compressão em duas direções ortogonais, normal e paralela à junta. Para o estudo das vigas são realizados trinta e sete ensaios, nos quais são avaliadas as influências da geometria, das taxas de armaduras e da relação a/d (em que a é a distância da carga aplicada até o apoio e d é a altura útil) na capacidade resistente ao cisalhamento. Posteriormente, é realizada a modelagem numérica através do software DIANA® com o propósito de complementar as análises dos ensaios. A partir dos resultados experimentais e numéricos pôde-se concluir que, com exceção das vigas com armaduras longitudinais de 10 mm de diâmetro, os demais modelos atingiram a ruína por cisalhamento, devido à ausência de estribos ou pela sua insuficiência. O aumento da taxa de armadura longitudinal de 0,45 para 1,18% resultou em um incremento de 18,4% na resistência ao cisalhamento convencional. Para as duas geometrias (vigas com duas e três fiadas) e as duas relações a/d (0,77 e 1,72), constatou-se que não há uma melhora significativa na capacidade resistente quando a taxa de armadura transversal é aumentada de 0,05 para 0,07%. Os mecanismos resistentes, como o efeito de pino, foram efetivos na resistência dos modelos. Por fim, as análises numéricas reproduziram de forma satisfatória os experimentos, tanto no que diz respeito ao comportamento pré e pós-pico quanto na previsão da força última. / This work is an in depth study about the mechanical behaviour of masonry beams subjected to shear forces. An extensive literature review, which establishes a panorama on the subject, an experimental program considering material characterization and full scale beams tests and a numerical study for the tested beams are presented. For the beams, thirty seven tests are carried out in which the influence of geometry, reinforcements ratio and a/d ratio (where a is the distance from the load to adjacent support and d is the effective depth) on the shear strength are evaluated. Computational modelling is performed using the DIANA® software in order to complement the experimental results. From the experimental and numerical results it was possible to conclude that, except for beams with 10 mm diameter steel bar, the other models failed in shear, due to the absence of stirrups or their insufficiency. An increase in longitudinal reinforcement ratio from 0,45 to 1,18% improved the theoretical shear strength in 18,4%. For the beams with two and three courses and for a/d ratios 0,77 and 1,72 it was found that there is no significant improvement on the load capacity when the transverse reinforcement ratio is increased from 0,05 to 0,07%. Shear strength mechanisms, such as the dowel action, were effective in the models load capacity. Finally, the numerical analyzes satisfactorily reproduced the experiments, regarding to the pre and post-peak behaviour and in the prediction of the ultimate load.