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Disertaciones |
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1
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Lucas Gabriel Lopes da Silva
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INFLUENCE OF EXECUTIVE VARIABLES ON THE MECHANICAL BEHAVIOR OF SELF-DRILLING TUBULAR MICROPILES IN TROPICAL SOIL.
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Líder : RENATO PINTO DA CUNHA
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MIEMBROS DE LA BANCA :
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RENATO PINTO DA CUNHA
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ENNIO MARQUES PALMEIRA
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GREGORIO LUIS SILVA ARAUJO
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Leandro Neves Duarte
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Data: 16-ene-2023
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Resumen Espectáculo
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This work aims to contribute to the knowledge of self-drilling tubular micropiles installed in the soil of Brasilia. This pile is one of the “Cast-in-place” type and for its molding a rotary drilling with simultaneous injection is used. Eight load tests were carried out on isolated piles, varying the parameters of injection pressure, diameter and length; and four other load tests in groups of two, three, four and five piles, all with the same executive characteristics. The diameters analyzed for the isolated piles were 200 and 260 mm, and the diameter used for the group piles was 200 mm. The injection pressures used were 200 kPa and 250 kPa for isolated piles and 200 kPa for group piles. The length used for the isolated piles was 8 m and 12 m and for the group piles the length was 8 m. The efficiency of the group of piles at 10% and 5% of settlement normalized by diameter was also analyzed. It can be concluded from this work that the adequate choice of the executive characteristics of the pile allows the optimization of the foundation system. This type of pile proved to be a viable alternative for porous soils with low resistance to penetration (Nspt) such as those in Brasilia, as it can offer technical, economic and environmental advantages in relation to other types of piles, mainly those related to their high execution speed and low cost.
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2
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Vinícius Silveira Levay
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INFLUENCE OF MOISTURE CONTENT ON THE TEST OF RESILIENCE MODULES IN BR-319/AM AND BR-156/AP SUBGRADE SOILS FOR APPLICABILITY IN PAVEMENT
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Líder : MICHELE DAL TOE CASAGRANDE
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MIEMBROS DE LA BANCA :
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ANTÔNIO CARLOS RODRIGUES GUIMARÃES
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MARCIO MUNIZ DE FARIAS
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MICHELE DAL TOE CASAGRANDE
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RAFAEL CERQUEIRA SILVA
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Data: 27-ene-2023
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Resumen Espectáculo
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During the useful life of the pavement, variations in moisture occur due to environmental factors, influencing the support capacity and the resilience modulus of the materials. The main objective of this research is to evaluate the influence of moisture on the resilience modulus, adopting the compaction moisture variations of +2% and -2% in relation to the optimum humidity. The research includes 19 soils located on BR-319/AM and BR-156/AP, for different applications. The granulometry tests by sedimentation, Atterberg limits, real grain density, miniature compaction, and mass loss by immersion (the latter two being used for the MCT classification) were carried out, as well as the resilience modulus test. For the concentrated loan soils, stabilized with lime, in addition to these, the lime content estimation test was also carried out by the pH method and the expandability test. The results obtained for the BR-319/AM soils showed that they are fine soils, classified as NG', with a high mass loss by immersion and an average reduction of 55.8% in the resilience modulus, with the addition of 2% of moisture. The chemical stabilization of the soil with lime proved to be promising, reducing the expansibility and the negative effect of water on the soil. The BR-156/AP soils showed a lateritic behavior, where a 2% increase in moisture reduced the material's resilient behavior by around 30%. Among the three evaluated models, the composite model used in the National Dimensioning Method (MeDiNa) was the most adequate, regardless of moisture content. moisture variations during compaction have shown to considerably reduce the resilience modulus of all studied soils. The present work contributes to the understanding of soils in the northern region of the country and reinforces the deepening of the understanding of the variation of moisture in the mechanical performance of pavements.
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3
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André Rodrigues
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Use of MediNa in basic asphalt pavement solutions in the Federal District
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Líder : MARCIO MUNIZ DE FARIAS
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MIEMBROS DE LA BANCA :
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MARCIO MUNIZ DE FARIAS
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MARCOS ANTÔNIO FRITZEN
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MICHELE DAL TOE CASAGRANDE
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RENATO PINTO DA CUNHA
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Data: 27-ene-2023
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Resumen Espectáculo
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The computational program MeDiNa allows the verification and empirical mechanistic design of asphalt pavement structures through the application of the theory of multiple elastic layers. Among its functionalities is obtaining parameters of deformability of layer materials, which allow evaluating the behavior of existing pavements by means of retroanalysis of deflectometric basins. Therefore, the objective of the present study was to initially evaluate the consistency of the resilience modules obtained by the program, as well as the adherence of the simulation of the pavement service life to the conditions observed in the field. For that, a set of data collected in 8 (eight) Sampling Units (homogeneous segments with 1 km in length) different from the DNIT, located in the region close to the Federal District, including the characteristic traffic, the Longitudinal Irregularity Index (IRI), the percentage of cracked area of the pavement, thickness information and physical characterization of its layers obtained through inspection wells, as well as data from deflectometric basins measured by FWD equipment. After verifying the hypothesis that the Transfer Function of the program offers conditions of use for the region, a second stage was established. This stage consists of presenting guidelines, based on precision levels, for the best use of MeDiNa in asphalt paving projects, as well as its use for structural quality control of these pavements, since the tool has a useful life forecast model based on in criteria of rupture due to fatigue and permanent deformations, which reflect in cracking in the asphalt coating and sinking of the wheel track.
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4
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Johanna Augusta Arend dos Santos
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Use of the Multicriteria Method for Decision Making in the Definition of Possible Areas for the New Sanitary Landfill of the Federal District
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Líder : ANDRE LUIS BRASIL CAVALCANTE
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MIEMBROS DE LA BANCA :
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ANA CRISTINA SANTOS STRAVA CORREA
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ANDRE LUIS BRASIL CAVALCANTE
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MICHELE DAL TOE CASAGRANDE
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RAFAEL CERQUEIRA SILVA
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Data: 30-ene-2023
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Resumen Espectáculo
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In 2018 the Brasília Landfill (ASB) was inaugurated in the Federal District as a result of the PNRS (2010) publication, which began to receive the solid waste generated in the capital. In addition, several initiatives were developed to reduce the volume of landfilled waste. However, the landfill that had been planned for thirteen years was now expected to operate for a little more than ten years, since the actions were not very effective. With the observed increase in landfilled waste, it will soon be necessary to find another place to landfill the waste. There is also the possibility of expanding the ASB. The present work evaluated the possibilities of location for a new landfill to serve the population of the DF, considering the Integrated Development Region (RIDE/DF). To this end, Hierarchical Process Analysis (AHP) and Boolean Logic were employed. Both methodologies were validated through bibliographic research of works with the same theme. The AHP was developed and the criteria were defined and weighed based on the conclusions coming from the research of similar works. Eleven criteria were chosen: Water Resources; Slope; Soil; Groundwater; Conservation Areas; Geology; Highways; Distance to Airports; Distance to Urban Centers; Land Use and Land Cover; Towns and Villages. The use of Boolean logic was carried out through the interpretation of the legislation applicable to the case, defining restrictive criteria that were incorporated into the AHP with a zero score. A calculation was also made of the land area needed for the landfill, to serve the entire population of the Federal District over 20 years. The development of the work was done with the help of GIS tools and the data used was downloaded from public portals and independent projects. Maps were generated for each criterion that was crossed, arriving at a map with areas defined as "inadequate", "too little adequate", "little adequate", "adequate" or "very adequate". With this result, a filter was made among the "very suitable" areas to arrive at a location that could meet the expected population, that was defined as a preferred region.
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5
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JOÃO PAULO TAVARES SOUZA
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ANALYSIS OF THE DECHARACTERIZATION OF TAILINGS DAMS USING THE OLSON METHOD
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Líder : ANDRE PACHECO DE ASSIS
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MIEMBROS DE LA BANCA :
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ANDRE LUIS BRASIL CAVALCANTE
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ANDRE PACHECO DE ASSIS
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MANOEL PORFIRIO CORDAO NETO
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TEREZINHA DE JESUS ESPÓSITO BARBOSA
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Data: 08-feb-2023
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Resumen Espectáculo
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After the accidents at Fundão Dam and Dam 1 of the Córrego do Feijao Mine, Law No. 14,066, of September 30, 2020, decreed the need to decharacterize all upstream tailings dams in operation in the country until February 25, 2022. Since this is an activity that has been poorly studied and with incipient definitions of construction processes, mapping alternative executive methodologies for the decharacterization of tailings dams is of utmost importance. In this context, the aim is to evaluate the susceptibility to liquefaction, using the Olson Method, of a typical section of a tailings dam raised upstream, considering the total removal of material from the structure as the decharacterization methodology. The Olson Method is an empirical technique that uses correlations of SPT and CPT test results to analyze the liquefaction potential of soils. This method is divided into three steps: in the first, it aims to verify the susceptibility of liquefaction of the material, then, it aims to verify the possibility of triggering liquefaction and, finally, the Safety Factor of the liquefied material. Two different construction methodologies were evaluated: removing material from the dam in the downstream to upstream direction and in the opposite direction, from upstream to downstream. The results indicate slightly higher Safety Factors in the analyses considering material removal from downstream to upstream. The higher elevations present lower Factors of Safety in both scenarios, where there is a high relevance of the tailings strength ratio in the overall stability of the structure. As excavation occurs, the strength parameters of the starter dam and raising become predominant, increasing the Factors of Safety in all types of analysis and causing the results of the liquefied analyses to approach the peak scenario values. It can be seen, therefore, that with the progress of the decharacterization, there is no significant influence of the tailings strength properties on the overall stability of the structure, a result in line with what was expected and that corroborates with most of the decharacterization works currently being executed in the country.
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6
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Mario René Rivera Osorto
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ENVIRONMENTAL IMPACT ASSESSMENT OF PAVEMENTS WITH THE ADDITION OF RECYCLED POST-CONSUMER POLYETHYLENE TEREPHTHALATE (RPET) THROUGH THE LIFE CYCLE ASSESSMENT (LCA) METHODOLOGY
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Líder : MICHELE DAL TOE CASAGRANDE
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MIEMBROS DE LA BANCA :
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MICHELE DAL TOE CASAGRANDE
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ANDRE LUIS BRASIL CAVALCANTE
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RAFAEL CERQUEIRA SILVA
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Luciana Michèlle Dellabianca Araújo
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Data: 16-feb-2023
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Resumen Espectáculo
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The present study presents a cradle-to-built life cycle assessment (LCA) for a road pavements structure of hot mixed asphalt (HMA) with recycled post-consumer polyethylene terephthalate (RPET) addition through the “dry” process using a comparison analysis between declared units equivalent of 1 ton of produced mix and functional units equivalent of 1 m2 pavement variants under the Brazilian “National Design Methodology” (MeDiNa), in contrast with a conventional mix variant. The Tool TRACI 2.0 for reducing and assessing chemical and other environmental impacts was applied for each alternative, assessing the impacts into categories such as acidification, eutrophication, freshwater ecotoxicity, global warming potential, human health, ozone depletion, and smog formation. The life-cycle impact assessment results were interpreted through internal normalization criteria and weighting rule, obtaining an environmental score for each alternative, and allowing a straightforward stakeholder interpretation. Considering the better mechanical properties and overall functional performance of the HMA + RPET mixes, the functional unit comparison on LCA methodology results in savings in all environmental impact categories for each square meter of pavement constructed and ready to use. For the declared unit comparison point, a conventional HMA mix presents better overall environmental performance and wastes than a HMA with RPET added in aggregate substitution through the “dry” process. Considering the better mechanical properties and overall functional performance of the HMA + RPET mixes for the surface course, the functional unit comparison resulted in savings in almost all environmental impact categories for each square meter of pavement constructed and ready to use, with an overall layer thickness optimization effect that carries a cascade of upstream resource and emissions savings. This effect was explored with the sensibility analysis of net PET mass added by FU (functional unit), with an equilibrium mass identified for global warming potential and environmental score, establishing the ground for sustainable pavement definition and delimitation. It establishes a novel sustainability criterion for pavement structures with the addition of plastic post-consumer, which integrates the mechanical and environmental performance and allows for guidance in future plastic-pavement research.
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7
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Laura Honório de Oliveira Silva
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CARTOGRAPHY OF APTITUDE TO URBANIZATION: THE CASE OF THE PRATAGY RIVER WATERSHED
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Líder : NEWTON MOREIRA DE SOUZA
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MIEMBROS DE LA BANCA :
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JUAN FELIX RODRIGUEZ REBOLLEDO
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NEWTON MOREIRA DE SOUZA
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RAFAEL CERQUEIRA SILVA
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ROCHANA CAMPOS DE ANDRADE LIMA SANTOS
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Data: 23-feb-2023
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Resumen Espectáculo
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The disorderly growth of the city population resulted in an urban policy that perpetuates social inequalities. Thus, public space has been abandoned, reinforcing the idea of private property as the only safe place, and increasing economic distances with irregular occupation of peripheral and environmentally fragile areas. The urban expansion process depends on the incorporation of new areas and changes in land use, so that the city has a spatial organization that meets the demands of the new population. The general objective of this thesis is to explore cartographic methods and models to aid sustainable urban planning, based on the structuring of a progressive geotechnical mapping procedure, using geotechnologies and the theoretical basis of Geotechnical Cartography. For this purpose, data on different approach scales were used, with the aim of seeking suitable cartographic products to assist decision-making aimed at urban suitability. This study presents a quantitative approach and, from the point of view of technical procedures and based on satellite image classification, using methodologies such as Progressive Detailing and AHP (Analytic Hierarchy Process). The results obtained aimed at characterizing the susceptibility to hydrogeological processes, mass movement and erosion that served as the basis for the construction of the Geotechnical Chart of Aptitude for Urbanization of the Pratagy River Basin, respecting the legally imposed environmental restrictions.
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8
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Maria Camila Olarte Garzón
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MODELLING OF THE HYDROMECHANICAL BEHAVIOUR OF UNSATURATED SWELLING SOILS
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Líder : ANDRE LUIS BRASIL CAVALCANTE
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MIEMBROS DE LA BANCA :
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ANDRE LUIS BRASIL CAVALCANTE
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JUAN FELIX RODRIGUEZ REBOLLEDO
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RAFAEL CERQUEIRA SILVA
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JUAN CARLOS RUGE CARDENAS
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Data: 28-abr-2023
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Resumen Espectáculo
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Expansive soils are materials composed mainly of active minerals, such as montmorillonite, which tend to undergo volumetric changes due to moisture content migration. Different geotechnical engineering practices, such as the design of a dam core or the compaction of the subgrade, require a thorough analysis and prediction of the expansion phenomenon under unsaturated transient conditions. The main problem in evaluating the mechanical response of this type of soil lies in the nonlinear nature of most of the unsaturated properties, which requires sophisticated tools that include parameters that are difficult to obtain. This study performs a mathematical analysis to understand the hydromechanical behaviour of expansive soils under unsaturated transient flow. The implementation of two mathematical models based on the Richards (1931) equation using a simplified coupling is used to evaluate the approach. Based on experimental results obtained from soil-column tests, the behaviour of the resulting model under different suction and moisture content conditions is explored. Four cases of analytical solutions are established to build a model-specific response framework, each with restrictive assumptions tailored to an initial and two boundary conditions. In this case, the hydromechanical predictions in unsaturated flow are adjusted considering the variations of the void ratio along the expansion process to account for the impact of volumetric deformations on the model parameters. Finally, a parametric calibration with literature results is performed to evaluate the parametric sensitivity and the range of volumetric variation in which the model is constrained. The results indicate a high statistical proximity between the numerical estimation and the experimental data, with correlation factors higher than 97%, both in the wetting and drying paths of the void ratio - log suction curve. Likewise, the predictions of the analytical solutions for cases 1 and 3 are consistent for each parameter analyzed and work for unimodal and bimodal Soil Water Retention Curves.
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9
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ISABELLA MARIA MARTINS DE SOUZA
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APPLICATION OF CONSTITUTIVE MODELS WITH SUB-LOADING FOR THE ANALYSIS OF SLOPE STABILITY PROBLEMS
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Líder : MANOEL PORFIRIO CORDAO NETO
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MIEMBROS DE LA BANCA :
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JUAN FELIX RODRIGUEZ REBOLLEDO
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LUIS CARLOS DE SOUSA JUNIOR
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MANOEL PORFIRIO CORDAO NETO
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RAFAEL CERQUEIRA SILVA
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Data: 13-jun-2023
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Resumen Espectáculo
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Geotechnics is an important field due to the large scale and significance of its structures for society, such as dams, deposit piles, road cutting and filling, foundation of civil structures, and many other works where geotechnical knowledge is necessary for their execution. However, serious impacts on society are associated with this type of work, where the risks of failure can generate significant financial, environmental, and human life losses. Advances in geotechnical research allow for the improvement of numerical methods and constitutive models, seeking a better representation of the behavior of soil exposed to different boundary and loading conditions. Thus, models that can be used in the evaluation of geotechnical problems considering the particularities observed in tropical soils have been presented. Following this, an applied discussion shows the application of the Shear Strength Reduction (SSR) method considering the Modified Cam-Clay Hardening (MCC) critical state model. An evaluation of the performance of critical state models in laboratory testing was also carried out, indicating limitations of the MCC model for assessing the behavior of tropical soils. Finally, a simplification of the Madus Sub-loading model (Cordão Neto et al., 2009) was implemented in a commercial software for the development of a constitutive model that considers the critical state concept and the effect of sub-loading.
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10
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Flávia Augusta Padovani
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STUDY OF MECHANICAL BEHAVIOR OF MINING IRON ORE TAILINGS USING DISCRETE ELEMENTS METHOD
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Líder : LEANDRO LIMA RASMUSSEN
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MIEMBROS DE LA BANCA :
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ANDRE PACHECO DE ASSIS
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LEANDRO LIMA RASMUSSEN
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MARCIO MUNIZ DE FARIAS
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PAULO ROBERTO COSTA CELLA
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Data: 19-jun-2023
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Resumen Espectáculo
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The present work studied the influence of microscopic parameters on the mechanical behavior of iron ore mining tailings using the discrete element method (DEM). The two-dimensional program Particle Flow Code (PFC2D) from Itasca company was used for the numerical simulations of the laboratory tests that comprised of drained triaxial compression tests on sandy iron ore tailings samples. In the DEM model, drained biaxial compression tests were simulated on numerical samples with a grain size distribution curve proportional to that of the mining tailings and with a relative density between 60-65% for the confining stresses of 100, 200, and 400 kPa, which represent the same conditions adopted in the laboratory tests. In order to represent the effect of the irregularities in the shape of the tailings grains, the Rolling Resistance Linear Contact Model (RRLCM) was used in DEM simulations. The micromechanical properties of the numerical sample, such as the normal and shear rolling stiffness, and the rolling friction coefficient, were selected using a proposed methodology for calibrating the model in order to reproduce the overall mechanical behavior observed in the laboratory tests on mining tailings. The macroscopic mechanical behavior was evaluated in the DEM model based on the contact force network, velocity vectors, rolling resistance, particle rotation and coordination number measured from the interactions between particle-particle and particle-wall. During the simulations of the drained biaxial tests, it was also possible to identify the location and inclination of the shear band. In conclusion, the results obtained from the DEM model using the RRLCM model indicated good agreement between the stress-strain response and the experimental data from the laboratory tests. However, the volumetric deformation curves were not able to fully represent the volumetric deformation of the tailings due to the simplifying assumptions adopted in the model development. In summary, the present work provides a starting basis for further investigations of mining tailings using DEM.
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11
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Sonny Albert Amorim da Silva
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"Quantification of leaks through damages in geomembranes under different conditions"
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Líder : ENNIO MARQUES PALMEIRA
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MIEMBROS DE LA BANCA :
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ENNIO MARQUES PALMEIRA
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GREGORIO LUIS SILVA ARAUJO
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MARIA DAS GRAÇAS GARDONI ALMEIDA
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RAFAEL CERQUEIRA SILVA
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Data: 26-jul-2023
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Resumen Espectáculo
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Leakage through mechanical damages is a critical concern in geosynthetic systems, particularly with the use of PVC (polyvinyl chloride) and HDPE (high-density polyethylene) geomembranes. Mechanical damages can occur during installation, operation, or as a result of external factors causing punctures, cuts, or abrasions. This study aimed to evaluate water leakage through mechanical damages in smooth PVC and HDPE geomembranes with a thickness of 1 mm. Longitudinal cuts of 5 mm, 20 mm, and 50 mm were made using a blade, and holes of 2.2 mm and 5 mm were created to simulate damages in the geomembranes during installation and soil cover placement. Leakage tests were conducted using equipment developed at the Geotechnical Laboratory of the University of Brasília, applying hydrostatic pressures of 20 kPa, 100 kPa, 200 kPa, 400 kPa, and 800 kPa, equivalent to water heads ranging from 2 m to 80 m of water. The study has applications in geotechnical engineering projects such as dams, channels, and waste disposal areas, where leakage may occur under high pressures. The objective was to understand the factors that influence leakage rates and to develop methodologies to mitigate potential risks. The results showed that leakage intensity depends on various factors, including hydrostatic pressure, water temperature, and geometric characteristics of the damage (size and shape of the mechanical damage), which significantly affect the leakage rate. Larger damages tend to result in higher leakage compared to smaller ones, and hole damages appear to be more critical than linear cuts. The presence of sharp edges or irregularities in the damaged area can also influence leakage. PVC geomembrane barriers showed lower leakage compared with HDPE geomembranes. To mitigate leakage, it was observed that applying powdered bentonite under the geomembrane and in direct contact with the damage helped seal the leakage (using hydraulic barrier GM/GCL-D-F5). Therefore, understanding the behavior of PVC and HDPE geomembranes when subjected to mechanical damages is crucial for the design and performance of geosynthetic liner systems. Continued studies to minimize leakage rates through appropriate installation practices, material selection, and timely repairs are important to ensure the long-term effectiveness and reliability of geomembranes in various geotechnical applications
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12
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Matheus Lima de Barros
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GEOTECHNICAL BIM AND GIS INTEGRATION TO AQUIFER RECHARGE AREAS CHARACTERIZATION IN THE CONTEXT OF SMART CITIES
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Líder : ANDRE LUIS BRASIL CAVALCANTE
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MIEMBROS DE LA BANCA :
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SERGIO SCHEER
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ANDRE LUIS BRASIL CAVALCANTE
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NEWTON MOREIRA DE SOUZA
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RAFAEL CERQUEIRA SILVA
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Data: 28-jul-2023
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Resumen Espectáculo
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The water present in aquifers has different uses in the Federal District (DF), including domestic supply, the service sector, industrial uses, mining, agriculture and recreation. With the increasing demand for fresh water and its withdrawal from aquifers, an active management of these water resources becomes necessary. The surface areas where precipitation allows water to infiltrate and be transported to the aquifers are called recharge areas. In the area of infrastructure, the use of BIM is on the rise and often associated with the use of GIS tools. The use of both technologies is usually referred to as GeoBIM. Industry 4.0 contemplates the innovations that impact the production processes of the current era, such as large databases, smart cities, machine learning, and the integration of BIM and GIS technologies themselves. The general objective of the dissertation is to characterize aquifer recharge areas in the Federal District (DF) from a geological-geotechnical point of view, with the support of Geotechnical BIM and GIS tools to allow decision making in monitoring and intervention actions. The work was guided from a GeoBIM Execution Plan (GEP), a new concept introduced in the elaboration of the dissertation aiming the standardization of BIM and GIS data. A suggested topic structure for the document was presented, with descriptions and applications in the context of the presente work. From the consolidation of a database for aquifer recharge analysis in DF, a multicriteria analysis with the hierarchical process analysis (AHP) technique was performed with the criteria in descending order of weights: fractured hydrogeology, precipitation, geomorphology, slope, pedology, water depth, lineament density , use and cover and roughness. A case study was conducted for a pilot area at FAL-UnB, according to the Progressive Detailing Methodology, with the refinement of the criteria used in the DF analysis with field surveys and IoT sensor data. The cartographic products generated were compared with previous studies, which convergences were noted. From a data perspective, a proposed data standardization was proposed for the Guelph permeameter test, from the mapping of relevant information by the literature review. A Geotechnical BIM application was performed for auger holes in the pilot area of the FAL-UnB, with 2D and 3D visualization of soundings with the insertion of information in the objects. A GeoBIM application was performed demonstrating the dynamic connection between Autodesk and ESRI cloud for the modeling of the auger holes. It is noteworthy that the multicriteria analysis applied in the context of aquifer recharge was satisfactory, with the identification of areas of higher and lower suitability. It is emphasized that the adoption of BIM is a process that requires a change in culture, not just software. The integration between technologies for geotechnical in the context of Industry 4.0 requires structured data, which makes initiatives focused on standardization fundamental.
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13
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ANDERSON GUSTAVO VILLAMIL GONZALEZ
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AVALIAÇÃO DE REDE NEURAL ARTIFICIAL PARA PREVER A RESISTÊNCIA AO CISALHAMENTO DA INTERFACE AREIA-GEOMEMBRANA
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Líder : GREGORIO LUIS SILVA ARAUJO
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MIEMBROS DE LA BANCA :
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GREGORIO LUIS SILVA ARAUJO
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ENNIO MARQUES PALMEIRA
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MANOEL PORFIRIO CORDAO NETO
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PAULO CÉSAR LODI
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Data: 03-ago-2023
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Resumen Espectáculo
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The implementation of waterproofing systems during the construction of dams, landfills, and artificial channels is crucial to avoid fluid infiltration into the foundation soil, which can lead to structural damage and other potential hazards. Geomembranes are widely used in civil engineering as they offer excellent waterproofing capabilities, low permeability, and favourable mechanical properties. Like other construction materials, evaluating the strength at the interface between geosynthetics and in-contact material is necessary to ensure enough resistance to potential failures. Various laboratory tests can be conducted to ensure adequate interface resistance, such as direct shear, ring shear, and inclined plane. These tests determine the friction angle, a critical factor in determining the interface shear strength between granular soil and geosynthetics. However, these tests can be time-consuming and expensive and may only sometimes be feasible in project planning. Therefore, finding alternative methods to obtain the necessary information is essential. One possible solution is to use reference results from other research. In this way, a database of previous results can be compiled, and a predictive model can be created to estimate the required interface strength values. This study aims to assess the effectiveness of using an Artificial Neural Network (ANN) methodology to predict the shear strength at the interface of sand and geomembrane. A Multi-Layer Perceptron (MLP) architecture was chosen to configure the ANN models, and the training process is a supervised one that involves a Back-Propagation (BP) training algorithm coupled with the Differential Evolution (DE) optimization algorithm. The input data for the models were defined from 428 laboratory tests reported in previous investigations, including 14 input parameters and sand-geomembrane interface strength results. Four ANN models were analysed and compared, differentiated in terms of their number of inputs (9 or 14) and the number of hidden layers (1 or 2). The ANN model with the architecture 14-71-342-1 displayed the most satisfactory results for the training and testing phase in terms of the predicted values' distribution compared to the trend line (R²: 0.919 training, R²: 0.852 testing), a lower number of residual values outside the acceptable range (4% training, 11.6% testing), and excellent prediction performance according to statistical metrics for both phases (RMSE: 1.92, MAE: 1.32, MAPE: 5.03% training, RMSE: 0.852, MAE: 3.36, MAPE: 7.13% training). Based on the results, the ANN technique can be defined as an effective approach for predicting sand-geomembrane interface strength values (friction angle) for the collected data.
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14
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MAYARA LUANA DE JESUS SANTOS
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Mechanical Performance and Durability Evaluation of Bamboo Sawdust, Coconut Fibers, and Açaí Fibers as Reinforcement Materials for Tropical Soil.
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Líder : MICHELE DAL TOE CASAGRANDE
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MIEMBROS DE LA BANCA :
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MARIANA VELLA SILVEIRA
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ANDRE LUIS BRASIL CAVALCANTE
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MICHELE DAL TOE CASAGRANDE
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RAFAEL CERQUEIRA SILVA
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Data: 11-ago-2023
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Resumen Espectáculo
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The present experimental study addresses the proper disposal of agricultural residues, such as bamboo sawdust, coconut fibers, and acai fibers. Improper disposal of these materials leads to irresponsible environmental waste. To tackle this issue, the research line on new geotechnical materials proposes the use of these residues as soil reinforcement. The study investigates the interaction of these vegetative reinforcements with tropical soil over time, taking into consideration degradation processes resulting from environmental factors. Additionally, it examines the properties of these vegetative residues and how they influence the mechanical and durability characteristics of the composites. It also proposes a correlation by analyzing the Key Parameter curves that translate the interaction between composite properties and simple compression strength.
The results show that initially, composites reinforced with bamboo sawdust exhibited a pronounced peak in strength, surpassing coconut fibers and acai fibers. However, their strength rapidly decreased after the peak, unlike coconut and acai fibers, which maintained high values. In terms of maximum strength and post-peak strength, acai fiber outperformed coconut fiber. During the 6-month exposure to weather conditions, all reinforcement materials showed a loss of strength, but coconut fibers and acai fibers continued to contribute as reinforcement elements in the tropical soil matrix, as their simple compression strength remained higher compared to unreinforced tropical soil. Over the months, coconut fibers exhibited a considerably lower reduction in strength compared to the other materials, demonstrating their resistance to degradation.
Although vegetative materials have disadvantages such as variations in mechanical properties and susceptibility to degradation, their use is feasible in situations where immediate stabilization of the construction is required. This study contributes to understanding the behavior of these composites, highlighting the potential for reusing vegetative waste in geotechnical engineering as a sustainable alternative.
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15
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DELLANE STEPHANI CARVALHO DOS SANTOS
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Behaviour of geotextile filters in internally unstable soils under confinement
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Líder : ENNIO MARQUES PALMEIRA
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MIEMBROS DE LA BANCA :
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EDER CARLOS GUEDES DOS SANTOS
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ENNIO MARQUES PALMEIRA
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GREGORIO LUIS SILVA ARAUJO
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RENATO PINTO DA CUNHA
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Data: 16-ago-2023
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Resumen Espectáculo
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This dissertation addressed the study of the filtering behavior of non-woven geotextiles in internally unstable soil under confinement. Permeability tests were carried out under constant head conditions using a permeameter equipped with a device for the application of vertical stresses. The non-woven geotextiles tested had masses per unit area of 200, 400 and 600 g/m², the soil was composed of sand plus different percentages (0, 10, 20 and 40%) of fine material and the applied vertical stresses were 0, 25 and 100 kPa. The drainage materials under the geosynthetic filter were steel spheres of 15 mm in diameter, with ratios between spacing (s) and sphere diameter (d) equal to 1 or 2, or just a perforated plate. A series of filtration tests was conducted under hydraulic gradients of 1 and 10. The results were discussed in terms of the permeability coefficient of the soil-geotextile system (ksg). At the end of the tests, the grain size distribution curves of the material at the base of the soil sample and of the material that impregnated or passed through the geotextile filter were obtained using a laser grain size analyser. The degrees of impregnation of the geotextiles were obtained after the permeability tests. In addition, permeability tests were also performed on the 200 g/m² geotextile after filtration tests. Tests with samples of sand plus 40% of fines with 5, 10 and 15 cm height were performed in order to evaluate whether the height of the specimen influenced the filter behavior. Sagging of the geotextiles in the void spaces between the spheres were also assessed. It was observed that the vertical stress at the top of the samples,the hydraulic gradient, the increase in the mass per unit area of the geotextile and the tests with only the perforated plate under the geosynthetic tended to reduce the permeability of the soil-geotextile system. Increasing the spacing between the spheres decreased ksg and favoured the formation of a blinding layer on the filter surface.
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16
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BRUNO LEITE RAMIRES SALDANHA
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"Flow Liquefaction Study on Occurrence in Unsaturated Mining Tailings"
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Líder : MANOEL PORFIRIO CORDAO NETO
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MIEMBROS DE LA BANCA :
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JUAN FELIX RODRIGUEZ REBOLLEDO
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Letícia Pereira de Morais
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MANOEL PORFIRIO CORDAO NETO
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RAFAEL CERQUEIRA SILVA
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Data: 18-ago-2023
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Resumen Espectáculo
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The objective of this study is to present the formulation of a constitutive model capable of
reproducing the static liquefaction phenomenon in unsaturated mining tailings. The Unified
Model for Sand and Clay (CASM) expanded to represent unsaturated behavior was
implemented in visual basic programming language. The experimental results of the Stava
Mine tailings were used as input data for calibration and validation of the model. undrained and
isotropic compression simulations were conducted, and the model was able to reproduce a
significant portion of the unsaturated behavior, including: the increase in preconsolidation
stress, the change in the slope of the normal consolidation line, and the wetting collapse
phenomenon. With respect to non-drained behavior, when applying different suction values,
the model was able to reproduce the increase in peak and residual stresses, the post-peak
behavior change, and the existence of a ratio between the average net stress and the matric
suction that increases the resistance to static liquefaction. For these and other reasons, the model
can be considered a good option for representing the static liquefaction phenomenon in
saturated conditions.
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17
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Felipe Marçal Barbosa de Melo Góis
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"GRAIN-SCALE FLOW MODELING IN POROUS MEDIA USING HYBRID NUMERICAL METHODS"
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Líder : MARCIO MUNIZ DE FARIAS
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MIEMBROS DE LA BANCA :
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ANDRE PACHECO DE ASSIS
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JUAN FELIX RODRIGUEZ REBOLLEDO
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MARCIO MUNIZ DE FARIAS
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MAURICIO MARTINES SALES
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Data: 15-dic-2023
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Resumen Espectáculo
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In the present work, grain-scale flow analyses in porous media are presented using hybrid numerical methods. Porous media made from virtual particles with realistic morphology are developed based on the characterization of real granular materials by digital image processing. After morphologically describing a large number of particles, a virtual repository is created with three-dimensional solids that statistically represent the shape of the real particles. The first of the numerical methods used is the algorithm for packing random particles from the repository that generates the virtual porous media. The algorithm is based on the discrete element method (DEM). The modeling of flow within the void matrix obtained from the virtual particle packings is then performed by a computational fluid dynamics (CFD) software. This eliminates the need to use a continuum approach for the porous medium. The methodology presented makes it possible to obtain the distributions of the characteristic flow variables throughout the porous matrix, rather than averaged values obtained for a representative elementary volume (REV). Six packings of virtual particles with different grain sizes were used, with dimensions varying between 4.8 and 32 mm. The results obtained here were then compared with the calculations from flow resistance models widespread in the literature, that were developed with the assumption of the porous medium as a continuous material. Furthermore, the numerical results were validated by experimental data obtained from laboratory tests using a hydraulic channel and real granular material used as a basis for assembling the virtual packings. The merge of numerical methods presented in this work proved to be quite effective, with great analytical value, with qualitative and quantitative advantages. The graphical features available in CFD modeling can be used as powerful tools for visualizing a complex phenomenon that occurs inside the pore network of geotechnical granular materials, represented virtually in an innovative realistic way.
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18
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Beatriz Mapa Clemente
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"APPLICABILITY AND RELIABILITY OF DISPLACEMENT MONITORING IN A MINING DAM USING THE INSAR TECHNIQUE"
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Líder : NEWTON MOREIRA DE SOUZA
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MIEMBROS DE LA BANCA :
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NEWTON MOREIRA DE SOUZA
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ANDRE LUIS BRASIL CAVALCANTE
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ANDRE PACHECO DE ASSIS
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Karla Cristina Araújo Pimentel
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Data: 18-dic-2023
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Resumen Espectáculo
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InSAR (Synthetic Aperture Radar Interferometry) has gained great visibility for dam monitoring purposes in the recent years, especially after the failure episodes of Fundão Dam in Mariana and B1 Dam in Brumadinho, in 2015 and 2019, respectively. The ability to monitor large areas at low cost, without the need to install any equipment in the field, has led to countless geotechnical structures being monitored by orbital radar to detect slow displacements, which can be precursors of instability and anomalies. The technique has also shown efficiency in indicate regions for the installation of complementary monitoring such as prisms and terrestrial radars, in addition to acting as a redundancy of displacement monitoring. Like any other technologies, InSAR also has limitations that need to be known for a better understanding of its results, such as the satellite line of sight and revisit time, the structure geometry, vegetation and existence of water or humidity. As it is a recently applied technique in dam monitoring, the national bibliography is still small, which leads to a small amount of knowledge about this monitoring and doubts related to the applicability and reliability of the delivered data. In this way, this research presents the deliverability of the InSAR technique, in the sense of applicability in displacements detecting that can be precursors of different failure modes and in anomalies monitoring, considering the Brazilian rules, the possible anomalous behavior and the main dam failures. Based on the results, InSAR monitoring was classified as a desirable, complementary, or not applicable monitoring for the identification of several geotechnical structure anomalies or places where anomalies could be developed. The research also presents an analysis of the functionality and technical reliability of the InSAR data for a mining dam case study. Comparative analyzes were conducted considering the monitoring data obtained from InSAR (COSMO-SkyMed constellation) and another traditional displacement monitoring technology, a Robotic Total Station. Due to the low difference between monitoring results using both techniques, the case study presented good reliability and contributed to increase the understanding about monitoring mining dams with InSAR.
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19
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DANIEL BATISTA SANTOS
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Transient slope stability in unsaturated soils by the general limit equilibrium method with analytical solution for the water infiltration
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Líder : ANDRE LUIS BRASIL CAVALCANTE
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MIEMBROS DE LA BANCA :
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ANDRE LUIS BRASIL CAVALCANTE
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Gilson de Farias Neves Gitirana Júnior
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JUAN FELIX RODRIGUEZ REBOLLEDO
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RAFAEL CERQUEIRA SILVA
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Data: 20-dic-2023
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Resumen Espectáculo
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Slopes are soil structures present in the landscape, whether naturally or in man-made geotechnical constructions. Slope failure is usually related to the variation in the water content within the soil during hydrological events such as intense precipitations. Thus, the global stability analysis in unsaturated soil slopes is needed. The present study models the transient factor of safety for global stability in homogeneous and unsaturated soil slopes using the Bishop and GLE (General Limit Equilibrium) limit equilibrium methods. Also, a semi-analytical solution for the transient two-dimensional water flow applied to an unsaturated shear strength model was coupled to the limit equilibrium modeling. This model was implemented in the Wolfram programming language in the Mathematica software. It allowed parametric analyses for the factor of safety varying with time during water infiltration or drying events, applying different boundary conditions for the water content and the slope geometry. This model also allowed the analyses of other state variables such as suction and shear strength. The results of the present model were compared to the results obtained by the same inputs in the commercial software package GeoStudio (Seep/W e Slope/W), presenting consistency amongst themselves for the adopted hypotheses. Some differences between the software for the formulation and the results were explained. The computational tool developed in the Mathematica can be applied in the geotechnical engineering practice for case studies in unsaturated soil slopes, and it may be improved for more complex modeling hypotheses, for both water flow and stability.
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Tesis |
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1
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Heitor Cardoso Bernardes
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Analysis of the Behavior of a Piled Raft Based on Columns and Foundation Instrumentation
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Líder : RENATO PINTO DA CUNHA
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MIEMBROS DE LA BANCA :
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ALEXANDRE DUARTE GUSMAO
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BERNADETE RAGONI DANZIGER
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GREGORIO LUIS SILVA ARAUJO
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JUAN FELIX RODRIGUEZ REBOLLEDO
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RENATO PINTO DA CUNHA
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Data: 24-ene-2023
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Resumen Espectáculo
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The lack of scientific papers involving the monitoring of loads, stresses and strains in the foundations of structures built on tropical soils is one of the limiting factors to the application of advanced techniques to the design of piled rafts as foundations of tall buildings in Brazilian soil. The present paper aims to understand the geotechnical behavior of a large piled raft using the monitoring of strains in the building’s columns and piles, the stresses at the raft-soil interface, and the foundation settlements. The thesis stands out from other related studies as it is the first Brazilian case contemplating this level of instrumentation of a high-rise building. As specific objectives, it is listed: the analysis of the load distribution between the piles of the group; the mobilization of stresses at the raft-soil contact; the mobilization of the lateral side friction of the piles along its depth; and the influence of the interactions between the foundation elements in the aforementioned topics. Field and laboratory tests were performed on-site, and associated with axisymmetric and three-dimensional finite element analysis to aid in the assessment of the measured data. The monitoring of pile strains suggests the occurrence of soil expansion, caused by the raft excavation process, up to approximately 6 months after the excavation was completed. The presence of different soil profiles under the raft, with different mechanical properties, affected the distribution of the foundation settlements and the pile loads. The measurements recorded by the total stress cells indicated that the mobilization of the resistance at the raft-soil interface was superior to the values predicted in the design phase. The effect of the superstructure stiffness contributed to successive load redistributions on the instrumented columns, which caused a uniformity in the foundation settlements and reduced the load difference between the piles positioned in different soil profiles.
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2
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Bruno Rodrigues de Oliveira
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Conceptual model and implemetation of a tridimensional geotechnical database (BDTG)
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Líder : NEWTON MOREIRA DE SOUZA
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MIEMBROS DE LA BANCA :
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ALEXANDRE DE AMORIM TEIXEIRA
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ANDRE LUIS BRASIL CAVALCANTE
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ANDRE PACHECO DE ASSIS
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CARLOS MEDEIROS SILVA
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NEWTON MOREIRA DE SOUZA
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Data: 09-feb-2023
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Resumen Espectáculo
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The demand for geospatial data today has grown exponentially and given the multiplicity of existing geotechnologies in the market, the production and distribution of data become more agile every day. The interest in georeferenced and structured geotechnical data tends to grow in Brazil due to the mandatory use of the Building Information Modelling (BIM) in the direct or indirect execution of engineering projects and services performed by the entities of the federal public administration or for the manufacture of cartographic products established in the National Policy of Protection and Civil Defense (PNPDEC). Regardless of the purpose of the geotechnical data produced, there is an absence of a storage pattern, a format of integration of the data by various sources and a quality control. Data produced is restricted to information producers causing waste of resources by thoroughly reinvestigating areas that could only be subjected to complementary investigation campaigns. If the management of geospatial data were done adequately, the time used in the compilation and compatibilization of pre-existing data could be invested in the planning of data acquisition, in the production and analysis of derived information. However, for pre-existing data to be used properly, together with the data produced, both need to follow standards and technical specifications that ensure interoperability, sharing, and dissemination. In this context, this research analyzed the relationship between different types of investigations and geotechnical tests and proposed a geospatial data model that defines relationship rules and three-dimensional geotechnical data storage patterns in the database. The rules and standards were presented in the form of conceptual schemes using the Object Modeling Technique for Geographic Applications (OMT-G), because it is a model compatible with the National Spatial Data Infrastructure (SDI). The OMT-G model proved to be adequate to express the relationships and three-dimensional representations of the geotechnical investigations and laboratory tests, although the model is commonly applied to the modeling of two-dimensional geographic data. For the validation of the proposal, a geotechnical database of the Federal District was implemented, using the proposed geotechnical data model, in the PostgreSQL Relational Object Database Manager System (RDBMS) spatially extended with PostGIS, which allowed the evaluation of the use of the data model in practical cases. Based on the geotechnical database, three case studies were conducted addressing data analysis and spatialization in the Olhos D'Água Stream sub-basin, construction of three-dimensional geometry and data selection criteria in the Taquari Housing Sector – Step 2 and analysis of geotechnical characteristics in terrain units defined based on geology, geomorphology and pedology. The entire geotechnical database structure is compiled into an extension to PosgreSQL titled "pggeotec" and available in the Github repository, aiming to stimulate discussion about storage standard and geotechnical data distribution architecture.
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3
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Narayana Saniele Massocco
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" Structure effect on compressibility and shear strength of a lateritic soil"
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Líder : MANOEL PORFIRIO CORDAO NETO
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MIEMBROS DE LA BANCA :
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Bruna de Carvalho Faria Lima Lopes
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JUAN FELIX RODRIGUEZ REBOLLEDO
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MANOEL PORFIRIO CORDAO NETO
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MARCIO MUNIZ DE FARIAS
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Sandro Lemos Machado
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Data: 27-mar-2023
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Resumen Espectáculo
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One of the main factors that influence the soil behavior is the structure in which a soil was formed. Therefore, studies have been developed in order to identify how the microstructure affects behavior. However, it is known that in lateritic soils aspects such as aggregation, cementation, pore distribution impact the hydraulic and mechanical response. In this sense, this work aims to verify the influence of these structural elements on the hydraulic and mechanical behavior of a metastable lateritic soil. The investigation proposed analyzes based on samples that have different structures: intact, compacted (in Normal and Modified Proctor energy) and reconstituted (with the use of dispersing agents such as distilled water and sodium hexametaphosphate) due to its bimodal structure. The hydraulic and microstructural tests, at first, made it possible to understand how these different samples behave and how they are structurally arranged. From this, it was possible to establish a quantitative, semi-quantitative and qualitative analysis of the pore distribution using MIP, SEM and granulometry tests. It was identified that the samples in the Normal Proctor energy have evident macropores, the modified energy has only micropores, and the reconstituted samples have reduced aggregation as well as the effect of the dispersing agent with the use of hexametaphosphate. These analyzes together with the consolidation tests made it possible to define the possible intrinsic state of the soil and quantify it in macropores and micropores. Finally, the direct shear tests provided, in addition to behavior analysis, to verify the arrangement of the aggregations after rupture from the removal of samples from a sheared band, which were sent to MIP and SEM tests at tensions of 70 kPa and 300 kPa. This made it possible to verify changes in the form of aggregation as well as orientation after shearing. In general, it is concluded that the effect of compaction on the structure is associated with the observation of dilatation and cohesive intercept values different from zero.
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4
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Raimundo Francisco Perez León
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Soil-lining interaction of tunnels built in soft soils subjected to pore pressure drawdown
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Líder : JUAN FELIX RODRIGUEZ REBOLLEDO
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MIEMBROS DE LA BANCA :
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GABRIEL AUVINET GUICHARD
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GREGORIO LUIS SILVA ARAUJO
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JUAN FELIX RODRIGUEZ REBOLLEDO
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MANOEL PORFIRIO CORDAO NETO
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MIGUEL ANGEL CABRERA CABRERA
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Data: 14-abr-2023
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Resumen Espectáculo
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In recent years there has been a marked increase in the use of tunnels built on soft soils, especially in urban regions, to serve a variety of purposes, such as transportation (road, rail and subway), and as part of sewage collection systems (Kochen, 2005). Many cities are developing on soft soils: Shanghai, Bangkok, Kuala Lumpur, Jakarta, Singapore, Bogota, Mexico City, among others. These cities have been presenting related phenomena such as the lowering of water levels in the soil that change the working conditions of underground structures (Rodríguez, 2016). Measurement of pressure in tunnel lining built in saturated clays in London, Chicago, and Detroit (Peck 1969; Tchebotarioff 1979) shows that vertical pressure evolves over time, sometimes exceeding the initial value of total ground pressure at tunnel axis level, γ*H0. An extreme case of this evolution corresponds to the soft clays subjected to a densification process induced by the abatement of the original hydrostatic pressure in the aquifers that underlie the lacustrine clays, as in the valley of Mexico; in this case, as the piezometric abatement increases, the top of the tunnel liner is subjected to load increases, and at the same time, the sides of the tunnel liner experience a loss of confinement due to reduced water pressure. Pressure differentiation induces important stresses on flexion and compression in the lining (Tamez et al., 1997; Rodríguez et al., 2013). In this work we study the soil-lining interaction of tunnels built in soft soils subjected to a consolidation process through physical modeling in geotechnical centrifuge, which allows to reproduce the field stresses in a model in a reduced version of the prototype and to accelerate the effects of consolidation phenomena, allowing a considerable reduction in the time scale in relation to the prototype. To obtain long-term stress distribution acting on the support when subjected to piezometric abatement, eight tension cells and five piezometers were installed in the tunnel lining, as well as 16 strain gauges to obtain bending moments and axial forces. In addition, five piezometers were placed in the soil mass at different depths to obtain the magnitude of the piezometric abatement and three surface extensometers to obtain the surface settlements.
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5
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Charles Pereira Chaves
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Laboratory study of energy piles thermal response test in unsaturated tropical soil.
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Líder : RENATO PINTO DA CUNHA
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MIEMBROS DE LA BANCA :
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CRISTINA DE HOLLANDA CAVALCANTI TSUHA
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ENNIO MARQUES PALMEIRA
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FERNANDO SABOYA ALBUQUERQUE JUNIOR
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RAFAEL CERQUEIRA SILVA
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RENATO PINTO DA CUNHA
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Data: 24-abr-2023
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Resumen Espectáculo
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The need to develop new energy efficiency technologies in low enthalpy geothermal systems has become increasingly common and necessary in geotechnics. Regarding piles heat exchangers, it is known that the development of the technology is linked to deep studies of several research centers in the world that are contributing to the technological advancement of the application of piles heat exchangers as an alternative to the efficient use of energy in buildings. In this sense, understanding in depth the behavior of the thermal properties of heat exchanging piles in tropical soils, facing geotechnical variations of specific weight and saturation degree becomes very challenging in geotechnical, This thesis aims to evaluate the thermal behavior of prototype heat exchanger piles made in typical tropical soil of the Federal District, in the compacted and unsaturated condition, in the 1m pile full-scale range, submitted to parametric variations of pipe configuration, saturation degree and internal flow in the pipes, all in a controlled laboratory environment, by means of a large-sized thermal chamber developed for this purpose. To achieve this goal, a thermal response machine was developed to perform the tests on the prototypes. Its experimental evaluations were performed, and with that, thermal response tests were compared, from the point of view of thermal gradient in 2D and thermal resistance in 1D. A study of the thermal properties of the typical lateritic soil of the Federal District was also done. In addition, a thermal well was also developed in which the temperature variations of a 12m deep geotechnical profile were monitored throughout 2 months. Finally, with the results of the thermal response tests, thermal response functions (G functions) were developed for each geotechnical situation in question, where the main geometric and geotechnical peculiarities of the prototypes were compared. Furthermore, the results of thermal conductivity were compared with the main models in force in the geotechnical doctrine, in which new parameters of adjustment of the main models of thermal conductivity in the current bibliography were proposed, as well as a new empirical model, quite accurate, of mathematical adjustment of the lateritic soil of Brasilia.
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6
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MICHAEL ANDREY VARGAS BARRANTES
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Evaluation of the behavior of geotextile tubes used in environmental protection works
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Líder : LUIS FERNANDO MARTINS RIBEIRO
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MIEMBROS DE LA BANCA :
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ENNIO MARQUES PALMEIRA
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GREGORIO LUIS SILVA ARAUJO
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RAFAEL CERQUEIRA SILVA
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Fernando Henrique Martins Portelinha
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MARIA DAS GRAÇAS GARDONI ALMEIDA
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Data: 27-abr-2023
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Resumen Espectáculo
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The construction of structures to protect against floods, water diversions, breaking waves through conventional construction methods has led to an increase in the use of alternative methods, including the use of geotextile tubes. This method has quick implementation as well as reduced costs. Other uses with of geotextile tubes have been directed to the dewatering of fine-grained materials resulting from industrial processes or wastewater treatment with different concentrations. However, few studies have been carried out to understand the behavior of these structures in terms of the type of geotextile and filling material and technique. In this sense, the present work aimed to study the behavior of geotextile tubes used in environmental protection works. For this purpose, tests were defined using sandy and clayey soils as filling materials and non-woven geotextile in the manufacture of tubes. Thus, filling of single and stacked tubes conditions were carried out. The tests were instrumented in order to obtain variations in the height of the tubes, pore pressures in the filling material as well as the vertical stresses at the base of the tubes. Variations in the deformation of the geotextile were obtained during the test and samples of the soil particles passing through the geotextile were collected for the study of its retention capacity. In addition, vane tests were performed on the filling material to obtain its undrained strength. Results for tubes filled with sand allowed analyzing the rapid stabilization process of the dewatering process, as well as the stabilization of stresses and pore pressures at the base of the tube and served as a reference to calibrate the system. After this process, the clayey soils were used to fill single and stacked tubes. The results obtained showed that the initial dewatering process was characterized by pore pressure peaks and total stresses at the base of the tubes that stabilized over time. The greatest deformations in the geotextile were obtained at the end of the filling process with small variations during the test. The variation of undrained strength with depth in the stacked tubes and in two of the single tubes showed a decrease in strength with depth due to the impermeable condition of the foundation. All these results showed the importance of verifying the behaviour of the nonwoven geotextile both for isolated and stacked tubes, which can modify the geometry and influence the dewatering process, the strength of the filling material and the strains in the geotextile.
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7
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Max Gabriel Timo Barbosa
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Study of the pulllout resistance of soil nails performed by means of the sectorized post grouting technique
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Líder : ANDRE PACHECO DE ASSIS
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MIEMBROS DE LA BANCA :
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ANDRE PACHECO DE ASSIS
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ENNIO MARQUES PALMEIRA
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FELIPE GOBBI SILVEIRA
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JUAN FELIX RODRIGUEZ REBOLLEDO
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PEDRO WELLINGTON GONÇALVES DO NASCIMENTO TEIXEIRA
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Data: 02-may-2023
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Resumen Espectáculo
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This thesis presents results of investigations carried out in real scale of the soil-nail interaction, especially in soil nails executed with sectored post grouting, through sub-horizontal and vertical pullout tests in real works and experimental campaign of soil nails. It was verified the sectored reinjection technique, a technique developed in Brazil for the execution of soil nails, obtained better results than the gravity grouted soil nails. By analyzing seven works executed in real scale, it was possible to propose an empirical model for estimating the pullout resistance of soil nails executed by sectorized post grouting. To validate the empirical model and observe executive influences of soil nail not investigated in works with post grouted soil nails, in addition to proposing a method of selection of executive technique of soil nails and previous pullout test alternatives as suggested by Seo et al. (2012), an experimental campaign was carried out in the porous clay of Brasília. In this campaign, the exhumation of soil nails was carried out to investigate the influence of the mean angle of surface roughness of the soil nails and the average exhumed diameters on the results of the pullout tests of the different executive techniques studied. After analyzing the results of the campaign, it was observed that drilling with water provided better results for all types of soil nails in the case of the characteristic soil of Brasilia and the use of additives in cement grouts can generate worse results due to the smoother interface and because of grouts with lower compressive strength, an important influence on pullout resistance. In addition to verifying the drilling method, superior results were observed in terms of pullout resistance for post grouted soil nails in relation to the other types of injection methodologies studied, with the proposed empirical model conservatively predicting the results of the pullout tests of post grouted soil nails. With the qualitative and quantitative validation of the sectorized post grouting, in real works prior to this thesis and in the field, the empirical model proposed was used satisfactorily in soil nail retaining walls in the state of Pará, Brazil, a place with a high number of retaining walls in soil nailing currently in execution. Furthermore, when comparing the subhorizontal and vertical pullout tests in the same location, it was verified that the results within the standard deviation of the mean of both test orientations allow not only the use of the empirical model proposed in this thesis, but also the use of vertical pullout tests as viable tools in the design and execution of post grouted soil nails.
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8
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Fabiani Maria Dalla Rosa Barbosa
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STUDY ON THE TECHNICAL VIABILITY OF THE DEEP MIXING METHOD (DMM) FOR FOUNDATIONS IN LATERITIC SOILS
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Líder : NEWTON MOREIRA DE SOUZA
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MIEMBROS DE LA BANCA :
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NEWTON MOREIRA DE SOUZA
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JUAN FELIX RODRIGUEZ REBOLLEDO
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RAFAEL CERQUEIRA SILVA
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ALEXANDRE DUARTE GUSMAO
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WILSON CONCIANI
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Data: 22-jun-2023
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Resumen Espectáculo
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Brazil is predominantly covered by soils with tropical characteristics. The state of Mato Grosso currently stands out as the country's main grain producer. The production, which requires storage, and the timely marketing of the crop have encouraged investments in grain storage facilities on farms. In addition, the state is expanding its road and rail network, consequently requiring foundations that meet the technical, environmental, and economic needs of these significant projects. Soil improvement techniques are seldom used in Brazil; however, outside the country, they have been widely employed in various forms and for different soil types, representing a technically and economically effective alternative. This research evaluates the technical viability of soil improvement for use in foundations set on unsaturated lateritic soil, with the addition of Portland cement using the Deep Mixing Method (DMM). The study area is located in the municipality of Primavera do Leste, MT. The soil in the study area was characterized with laboratory and field tests. The soil-cement mixture was initially analyzed as per the recommendation of the Swedish Geotechnical Society. The parameters consolidated in the literature are mostly applied to soft soils and organic soils. Therefore, to understand the behavior of the DMM in lateritic soils, 14 DMM piles were executed in the study area, with a diameter of 0.6 m and a depth of 3.5 m. It was concluded that if the geotechnical characteristics of the soil are evaluated before applying the DMM to lateritic soils and a careful study of the mixture with the soil is carried out, a good material for the piles is guaranteed. With the addition of 120 kg/m³ of Portland cement, an average reduced rupture stress through the global safety factor of 2 (σ50) of 500 kPa and a deformation modulus (E) of 25 MPa were obtained. These values indicate the possibility of applying the technique. In addition, environmental benefits are obtained such as reducing the exploitation of aggregates and reducing the emission of CO2 in the manufacture of cement, due to the reduced amount of binder per m³ of material.
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9
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Fernando Feitosa Monteiro
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BEHAVIOR OF BORED PILES EQUIPPED WITH THE EXPANDER BODY SYSTEM IN TROPICAL SOILS
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Líder : RENATO PINTO DA CUNHA
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MIEMBROS DE LA BANCA :
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GREGORIO LUIS SILVA ARAUJO
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JUAN FELIX RODRIGUEZ REBOLLEDO
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Paulo José Rocha de Albuquerque
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RENATO PINTO DA CUNHA
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Renato Resende Angelim
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Data: 14-jul-2023
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Resumen Espectáculo
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The evolution of construction has resulted in increased loads on foundations, making pile foundations the most commonly used solution. The Expander Body (EB) technology was introduced to improve the load capacity of piles and reduce uncertainties in the installation process, but in Brazil, the lack of scientific studies limits the design of these foundations. This thesis aims to analyze the mechanical behavior of bored piles equipped with EB technology, subjected to axial compression and uplift loads. Static load tests were carried out on conventional bored piles and bored piles equipped with EB technology at the Experimental Field Annex of the University of Brasília. The thesis addresses aspects related to the applicability of methodologies for predicting bearing capacity and displacement of piles, as well as the uplift versus compression behavior of piles equipped with EB technology. Comparative analyses of bearing capacity of EB-equipped piles and conventional piles are also presented, as well as numerical studies of load transfer mechanisms and failure surfaces of piles. Finally, load capacity coefficients are proposed for methodologies of bearing capacity prediction for EB-equipped piles and conventional bored piles based on lateritic soils. It was found that piles equipped with EB technology showed a load capacity gain of 32 to 40% in compression and 30% in uplift compared to bored piles without this technology. Displacement estimates were more consistent and accurate when obtained from deformation modules from in-situ tests compared to estimates from laboratory tests. For lateritic, collapsible, and unsaturated soils, frictional resistance ratios to compression and tension ranging from 0.86 to 0.98 were observed for bored piles equipped with the EB technology. Piles equipped with EB technology showed superior load capacity compared to other deep foundation construction methodologies, except for caisson foundations. The theoretical curves used to simulate EB expansion showed a good fit, with determination coefficients R² greater than 0.90. The numerical analyses were successful in comparison with the experimental curves, with correlation coefficients greater than 0.90. It was found that the failure surface for uplift piles resembles a curvilinear surface tangential to ground level, while for compression piles, it assumes a shape similar to that of a logarithmic spiral curve.
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10
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Luis Alonso Gonzalez Corrales
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Experimental evaluation of the pullout resistance of metalic and polymeric strips within construction and demolition wastes
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Líder : GREGORIO LUIS SILVA ARAUJO
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MIEMBROS DE LA BANCA :
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PAULO CÉSAR DE ALMEIDA MAIA
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JEFFERSON LINS DA SILVA
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GREGORIO LUIS SILVA ARAUJO
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JUAN FELIX RODRIGUEZ REBOLLEDO
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RAFAEL CERQUEIRA SILVA
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Data: 04-sep-2023
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Resumen Espectáculo
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Civil construction serves as a cornerstone for economic and societal progress within nations. However, its undeniable significance is accompanied by a concerning ecological footprint. Recent studies have indicated that the construction sector accounts for nearly half of global natural resource consumption and is responsible for a quarter of waste generation and CO2 emissions. This predicament underscores a pressing environmental challenge. In response, the recycling and repurposing of Construction and Demolition Waste (CDW) within the construction industry presents a potent avenue to safeguard natural resources, mitigate environmental impacts, and foster sustainable development. In this context, this study aims to assess the viability of employing CDW as structural fill material in mechanically stabilized earth walls through full-scale pull-out tests. To gauge its efficacy, the findings are juxtaposed against the geomechanical behavior of conventional natural sand, widely utilized in reinforced soil solutions. Furthermore, design parameters derived from laboratory tests, accounting for diverse design conditions, are compared against values established by standard technical protocols and design guidelines. Furthermore, a meticulous analysis of chemical and electrochemical attributes is conducted to evaluate durability and resistance to corrosion and degradation of reinforcement elements. Despite not fully conforming to the grain size distribution criteria stipulated by several international regulations – which advocate for the use of well-graded soils – the recycled CDW demonstrates commendable performance and remarkable mechanical characteristics, particularly regarding the resistance to pullout of metallic reinforcements with bumps and conventional synthetics. This performance level is on par with or surpasses that of natural sand, exhibiting comparable or superior pull-out resistance parameters. Consequently, the application of recycled CDW as an environmentally friendly alternative for total or partial replacement of conventional natural aggregates emerges as a promising solution. The viability of this approach is contingent upon satisfying additional design prerequisites. It is noteworthy that the recycled CDW gravel exhibits elevated concentrations of chloride and sulfate ions, alongside diminished electrical resistivity values. Complementing these findings, an analytical model is formulated based on pull-out tests, capable of predicting the response of metallic ribbed strips in alternative geotechnical materials, predicated upon their grain size distribution. This model adds a valuable predictive dimension to the utilization of sustainable materials in geotechnical engineering applications.
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11
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Luciana Barbosa Amancio
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MULTILAYER PERCEPTRON NEURAL NETWORKS APPLIED IN THE FORECAST OF THE LOAD CAPACITY OF ISOLATED AND GROUPED PILES
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Líder : RENATO PINTO DA CUNHA
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MIEMBROS DE LA BANCA :
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CRISTHIAN CAMILO MENDOZA BOLAÑOS
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GUILHERME DE ALENCAR BARRETO
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JUAN FELIX RODRIGUEZ REBOLLEDO
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MANOEL PORFIRIO CORDAO NETO
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RENATO PINTO DA CUNHA
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Data: 27-sep-2023
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Resumen Espectáculo
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Several researches have reported that the semi-empirical methodologies applied in the prediction
of the load capacity of isolated piles provide very dispersed results in relation to the values
acquired from load tests and, moreover, they disregard the effects of residual loads in their lateral
and tip portions. Considering that neural modeling with multilayer perceptrons has been
highlighted as a successful tool in predicting the behavior of isolated and grouped piles, it was
decided to use it in this research to develop prediction models for the lateral and tip plots of
isolated piles and also for the load capacity of groups of piles using the error back propagation
algorithm. To this end, results from SPT tests and instrumented static load tests were collected
from 120 isolated piles and from static load tests performed in 60 groups. With the information
related to the isolated piles, the lateral and tip plots of the isolated piles were calculated and
also the correction of these plots considering the presence of residual loads. This correction
implied a reduction in the lateral parcels and an increase in the tip parcels, of 22%. From the
load-strength curves corresponding to the 60 pile groups, the load capacities were determined
through the method of Terzaghi (1943). Then, the input variables for each of the neural models
were chosen, being the diameter, the resistance to penetration - SPT, the elevation of the water
level, the type of pile, the type of soil and the speed of the applied load those used in the models
referring to the isolated piles and the geometry of the group, the spacing between the piles, the
condition of the element that joins the piles and the load capacity provided by the neural model
developed in this work, those used in the models referring to the groups. After that, different
models were trained and validated with the help of the QNET2000 program. By comparing
the results obtained, it was possible to select a neural model for each variable that was to be
estimated. The correlation coefficients obtained in the validation phase of these models are between
0.88 and 0.99, a range that can be considered satisfactory for the prediction of a complex
phenomenon. Given the data used in the modeling, the proposed models for isolated piles had a
good performance for some types of piles (continuous and metallic propeller) while for others
(excavated) this did not occur. The model proposed to estimate the load capacity of pile groups
had an average performance, since it provided values far from the desired ones, especially for
the groups composed by hollowed piles or continuous flight augers. When applying the proposed
models in different cases, it was verified that the models related to the magnitudes of
the isolated piles had a better performance than the usual semi-empirical methodologies - Aoki
& Velloso (1975) and Décourt & Quaresma (1978) - and the model of the groups had a more
realistic behavior when the connecting element is not in contact with the soil. Therefore, it can
be stated that the multilayer perceptron is a promising tool for understanding the load transfer
mechanism that occurs both in isolated piles and in groups. It is worth remembering that the
difference between the models already available and those proposed in this work lies in the simplicity
of the architectures, in the fact that the lateral portion of the load capacity is calculated
as a function of depth and not just its total value, in the possibility of evaluating up to seven
types of piles, two types of loads (SML and QML) and different geotechnical profiles.
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12
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Jair Ochoa Valderrama
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Simulation of rock behavior at laboratory scale using the heterogeneous CVBM |
"Simulation of rock behavior at laboratory scale using the heterogeneous CVBM" |
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Líder : ANDRE PACHECO DE ASSIS
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MIEMBROS DE LA BANCA :
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ANDRE PACHECO DE ASSIS
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MANOEL PORFIRIO CORDAO NETO
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MARCIO MUNIZ DE FARIAS
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CARLOS ALBERTO LAURO VARGAS
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PEDRO PAZZOTO CACCIARI
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Data: 04-oct-2023
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Resumen Espectáculo
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With the increasing demand for underground construction projects, there has been a growing need to understand and predict the behavior of rocks when subjected to different types of external loads. Multiple experimental and numerical techniques have been developed to represent the various phenomena involving rocks and rock masses. One of these techniques is the Continuum Voronoi Block Model (CVBM), which, with its pseudo-discontinuous approach, has proven to be a numerical tool capable of simulating rock behavior on both field and laboratory scales, assuming a single material for the entire set of blocks and joints used in its representation. However, in recent years, the contribution of other sources of heterogeneity for a more accurate modeling of rocks has been recognized, allowing for more realistic failure modes and a development of macroscopic stresses closer to laboratory results, especially in cases of confined compression. For these reasons, in this work, material and contact heterogeneity were integrated into the CVBM using a script developed in the Python language. As a case study, the behavior of Äspö diorite was represented when subjected to different types of laboratory tests (simple and confined compression, indirect tension, cyclic loading, and fracture toughness), analyzing the impact of different parameters, the size of constituent elements, and spatial and structural variability on elastic response, characteristic stresses, and model strengths. The heterogeneous CVBM adequately simulated the rock's macroscopic response, capturing the natural variability of the results and the development of different types of fractures throughout the loading process. The new features added to the model resulted in early development of tensile stresses within the material, causing the gradual growth of fractures, impacting characteristic stresses and the extent of the unstable fracture growth zone. Additionally, other types of rocks with specific internal structural characteristics (foliation planes or inclusions) were represented, culminating in the extension of the procedure to the application of the probabilistic approach for defining properties within the test body.
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