Navegando por Orientadores "TEIXEIRA, Marcelo Rassy"

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Acesso aberto (Open Access)
Análise comparativa das sensibilidades obtidas com o vane test e o mini vane em um depósito sedimentar na foz do rio Amazonas
(Universidade Federal do Pará, 2022-11-22) VIEIRA FILHO, Arudá Gomes; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The reed test has been used in field research for the elaboration of geotechnical projects and in the management of non-clay sedimentary deposits, due to the fact that it provides data such as undrained shear strength (Su) and sensitivity (St). The same results are obtained in the test with the laboratory straw (mini vane), but for that, it is necessary to extract samples considered undisturbed, which, in this research, were recommended by the ABNT NBR 9820 standard. vane shear test with the laboratory vane test, also called Mini Vane. The location of this analysis is in a port region located at the mouth of the Amazon River, in a natural sedimentary deposit, which presented two slope disruptions with characteristics peculiar to soils with high sensitivity. Landslides on slopes are usually predictable from a geotechnical point of view, however in this researched region the soil presented rapid landslides on the slope, showing signs of a soil with high sensitivity. The research pointed out that the laboratory vane test (mini vane) presented a greater (St) when correlated with the (St) of the simple compression tests, giving greater clarity that there is a very soft clayey soil with a depth between 30 and 40 meters, typical of a ground lens that performed with high sensitivity. Comparisons between the reed tests showed consistency in the results, even in soil layers with different consistency indices than the initial layers, the validations of the reed tests were validated with the tests performed by simple compression. Finally, the soil of this deposit had its sensitivity identified in the field straw test. The same identification was confirmed on the Mini Vane. However, at depths greater than the field vane. In this way, the tests carried out by the Vane Shear Test (VST) in situ were primordial in the identification of the sensitivity, having its confirmation with the laboratory reed test (Mini Vane).
Acesso aberto (Open Access)
Análise experimental de consolos curtos de concreto com armaduras continuas e descontinuas
(Universidade Federal do Pará, 2019-09-30) ABRANTES, Jedson Henryque Corrêa; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
Short consoles, as well as some reinforced concrete elements, have discontinuity regions (D regions), where Bernoulli's hypotheses should not be taken into account, since stress flows do not distribute linearly along the cross section. In order to correct the disturbances caused by this flow in specific areas, it is necessary to look for alternatives of calculation through equations idealized by empirical perceptions of researchers, or by means of the Strut-and-Tie Method. In this context and after theoretical and experimental observations of consoles, it was concluded that it is formed in this structure a bottle-shaped strut, and although there is a considerable database in this regard, there is no consensus in the literature and among current codes that relate between continuous reinforcement rates, failure mode and strut efficiency factors . Thus, an experimental study was carried out to evaluate the contribution of three types of fibers (discontinuous reinforcement), polypropylene, polyethylene and steel, which were added to the concrete in three different contents for each one. The results showed that in general there were similar behaviors for the concrete readings, and the opposite when analyzing the continuous reinforcement that suffered tensile stresses (Tie). For the elements with metallic fibers the resistance gain in relation to the reference specimens was noticed for the part that received higher fiber content. For synthetic fibers, polypropylene fiber had better gain in the specimen with second best fiber volume, and for polyethylene was registered for the lowest percentage. These consoles also presented better ductile behavior among all the test elements that did not receive horizontal stirrups. Regarding the results compared to the specimen with continuous reinforcement only the one with polyethylene fiber achieved superior result. Regarding the strut efficiency factors, the method presented results against and in favor of safety, while with respect to the shear strength the codes estimates had very favorable results. Therefore, MBT is a very suitable method for design that presents efficiency and safety through structures that present stress and deformation disturbances.
Acesso aberto (Open Access)
Análise experimental do cisalhamento em vigas de concreto armado reforçado com microfibras
(Universidade Federal do Pará, 2019-01-31) OLIVEIRA, Mateus Gonçalves de; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The shear study for small, medium and large works, the latter known as works of art, with the use of reinforced or prestressed concrete presents particularities in the definitions of the traces, since, it has the need to minimize the propagation of fissures, as well as to obtain suitable mixtures considering the high characteristic high diameter of the large aggregates, as well as to avoid deleterious reactions in the concrete. In this sense, the main objective of this research is to analyze the shear behavior of reinforced concrete beams, with reinforcement of glass and polyester microfibers for each type of cited in volumetric fractions (0,024%, 0,032% e 0,048%), comparing them with the behavior of fiber- aiming its application in structural elements. In order to meet the proposal of this research, the methodology was based primarily on the characterization of concrete constituent materials (cement, small and large aggregates and fibers already mentioned), concrete dosage based on the Concrete Dosage method EPUSP -IPT, concrete of the beams, being: one of reference without fiber addition and 6 (six) with additions of microfiber of glass and polyester, being three (three) for each one of them, and later analysis as to shear through the breaking of the experimental beams, and computational analysis between the beam modeled in the Response 200 software considering stirrups throughout its section and the experimental reference without stirrups in 1/3 of its sections. It can be stated that the glass and polyester microfibers have shown that their uses can be used as partial replacement of the transverse reinforcement; contributed to post-peak or post-cracking stability; contributed to the gain in shear strength of 15.1% for VFV01 (beam with addition of glass microfibers with a percentage of 0.024%) and 21.6% of VFP02 (beam with addition of polyester microfiber with a percentage of 0.032%) both in relation to VR (reference beam). Therefore, this study demonstrated that the fibrous reinforcement can be used as control efficiency and as well as shear performance improvement in structural concrete.
Acesso aberto (Open Access)
Análise numérica da estabilidade de taludes utilizando o método de Galerkin livre de elementos
(Universidade Federal do Pará, 2017-05-03) SILVA, Davi Barbosa Costa da; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The safety of dams is associated to the stability of the structures that compose them. In a earthfill dam, there are mentioned the slopes, which are surfaces that form an angle with the horizontal one. Its study using numerical methods, like the finite element method (FEM), makes possible the estimate of displacements, stresses and strains. It is aimed in this study to contribute in the efficiency of the numerical analysis devoted to the slopes. Through the development of a resource turned specifically to dams, the objective in the present work is to present an algorithm able to check the stability of slopes in the period of its construction using a numerical method without mesh. For the proposed analyses, there was used the element free Galerkin method (EFGM), applying it in the strength reduction method (SRM). After the idealization of a model and solution using the limit equilibrium method and the strength reduction method with the help of the FEM, both in commercial software (GeoStudio), there were obtained and were compared the results of a model in which there is applied the strength reduction method with the use of the EFGM. The analysis by the strength reduction method was divided in determination of the in situ stresses of the foundation, construction of the landfill and strength reduction of the soil. Numerically, in the stage of getting the in situ stresses, the EFGM presented better result when compared to FEM, taking as a reference the classic mathematical model of the soil mechanics for subhorizontal surfaces. In the stages of construction of the landfill and of strength reduction, the relative approximation error the EFGM regarding the FEM was nearly always superior to 5%. However, it noticed if that in the main answers, i.e. in the determination of the slip surface and of the strength reduction factor, the results were similar, as in the strength reduction method, with the EFGM regarding the FEM, as that regarding the limit equilibrium method. In the comparison with the FEM, there were obtained more conservative strength reduction factors. In spite of being an information not available openly, it concluded if that the elastoplastic constitutive model used in the commercial software is not the linear elastic perfectly plastic model, which was hypothesis adopted for the EFGM. Besides the differences due to the behavior idealized for the material, the application of meshfree method also requires more studies related to the definition of the representation of the domain. The main advantage of the adoption of the proposed method is the possibility to test more parameters in less time, which makes it useful in preliminary construction studies. For that, it must be observed that, in spite of the limitations in displacement estimation, which are useful to associate numerical results to the observations in field, the conditions in which there is slip at slope can be appreciated in satisfactory, conformable way when it was shown in comparisons with the most used methods.
Acesso aberto (Open Access)
Avaliação da resistência ao cisalhamento em vigas de concreto armado reforçadas com macrofibras sintéticas
(Universidade Federal do Pará, 2019-02-01) SOUSA, Diego Lucena de; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
With the increased use of composite materials, in search of adding to the new technologies, and, through the application in synthetic fiber contents to the concrete, this material can add favorable characteristics in relation to the conventional concrete. From this finding, the present study applied 0.08%, 0.12% and 0.16% for polypropylene fiber and 0.24%, 0.36% and 0.48% for polyethylene fiber in reinforced concrete beams so that the appropriate contributions could be evaluated, when this element was subjected to shear stress. Thus, after the tests, it was possible to observe that the elements with fiber application obtained a resistance above, however, close to the beam produced with the reference concrete. In contrast, as the contents of both fibers were increased, it obtained a ductility increment, a fact proven by the graphics shear x vertical displacement, shear x concrete deformation and shear x bending armor deformation, since, among the fiber contents used, the percentages of 0.36 % and 0.48% of polyethylene and 0.16% of polypropylene were the ones that presented a critical volume corresponding to the fiber content closest to an ideal, thus demonstrating the proximity of the carrying capacity for such produced composite, from the rupture of its matrix. Therefore, according to Figueiredo (2000), the behavior change is a function of the fibers characteristics, the concrete matrix and their interaction. In this way, the material now has specific requirements for its quality control, dosage and even application, different from conventional concrete. In view of this, it can be stated that the application possibilities of the material are amplified, since the reinforced concrete with fibers presented technological advantages in relation to the conventional one, as it showed a more ductile behavior, absorbing na equal load capacity for a longer period of time.
Acesso aberto (Open Access)
Avaliação da sensibilidade de uma argila mole do Amapá por meio da correlação entre ensaios de CPTU e de laboratório
(Universidade Federal do Pará, 2022-11-03) GONÇALVES, Andrey da Costa; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The identification and mapping of sensitive soft clayey soils are of great interest for planning, design and protection purposes, as these materials can exhibit fragility, loss of strength and softening by deformation, in addition to being more prone to landslides. The occurrence of sensitive clays in the port region of the municipality of Santana, state of Amapá, region of the mouth of the Amazon River, motivated the study about the geological and geotechnical characteristics of the local soil. In this context, this research aims to evaluate the sensitivity of clays from a fluviomarine sedimentary deposit. The geotechnical investigation was divided into three areas, called investigation islands. On each island, piezocone tests (CPTU) were performed and undisturbed samples of high quality soil were collected for laboratory tests. Soil behavioral type abacuses (SBT), which use CPTU data, indirectly identified layers (lenses) of sensitive soft clays. Through the relationship between the undrained soil shear strengths (𝑆𝑢 and 𝑆𝑢𝑟), obtained by the unconfined simple compression test, the sensitivity values were directly obtained. The Atterberg limit tests, total granulometric analysis and moisture content, served to characterize the region's soil. The results showed that the sedimentary deposit is constituted mainly by silt and clay, of low resistance and high plasticity and compressibility, with moisture content close to 50%. The methods of Robertson (1990) and (2016) and Schneider et al. (2008) identified sensitive thin material. The clay showed 𝐵𝑞 values lower than 1.0. The results for 𝑆𝑢 were between 33.67 and 103.53 kPa, while for 𝑆𝑢𝑟 between 4.44 and 16.29 kPa. According to Skempton and Nortey's (1952) classification, 83.33% of the samples were classified as medium to extrasensitive clays, with a sensitivity range of 3.3 to 12.7 and an average of 7.06. Thus, the results were consistent with similar ones in the literature, evidencing the applicability of the geological geotechnical investigation for identifying and mapping sensitive soils in the Amazon region.
Acesso aberto (Open Access)
Confiabilidade aplicada à análise da estabilidade de taludes: um estudo de caso de uma encosta fluvial no norte amazônico
(Universidade Federal do Pará, 2021-04-02) NASCIMENTO, Rafael Silva do; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
Among the geotechnical structures, the river slopes stand out for the uncertainties in their properties. In addition, the use of coupled reliability methods in the analysis of slopes has grown, in contrast to deterministic methods that do not consider uncertainties. In this context, the present work presents the study of the reliability of a fluvial slope in the Amazon region that suffered a rupture. For this, three reliability methodologies were used (Monte Carlo, FOSM and PEM), using the limit equilibrium method and finite elements. The properties of the hillside soft clays were treated as random variables and the reliability indicators for each methodology were obtained. In addition, sensitivity analyzes of these parameters were carried out. The results of the slice models were compared to the numerical results. Finally, it was concluded that the uncertainties in the properties of soft soils were not sufficient to cause the rupture of the slope, therefore, another factor(s) must have triggered the rupture.
Acesso aberto (Open Access)
Eletroquímica coloidal e sua relação com a sensibilidade de um solo argiloso na foz do rio Amazonas
(Universidade Federal do Pará, 2023-06-29) SOUSA, Flaviany Luise Nogueira de; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
Clays have always played an important role in the history of civilizations, mainly because they are a mineral resource with varied technological applications. Among the several existing types, sensitive clays (quick clays), for example, are very complex soft soils that are considered real challenges for engineers due to the difficulty in obtaining their geotechnical parameters. In this sense, the aim of the present study was to analyze the sensitivity of a clay soil found in a region of the city of Santana, in the state of Amapá, Brazil. To this end, physical and chemical tests were carried out, including the SPT (Standard Penetration Test), X-Ray Diffraction (XRD), Zeta Potential (ζ), pH, Cation Exchange Capacity (CEC), as well as resistance assays (Vane Test and Fall Cone Test – FCT). The analyzed area is located in the Macapá Fluvio-marine Plain, which is composed of sediments that were deposited both by rivers and by the sea as a result of the region’s proximity to the mouth of the Amazon River. The geological profile obtained through geotechnical investigation indicated that the soil is constituted of mottled sandy-clay sediments, sandy-silty sediments with plant remains, and sandy- silty sediments with pebbles. As for the mineralogy of the samples, they were essentially composed of quartz and three clay minerals: kaolinite, mica/illite, and chlorite. Regarding sensitivity, all samples were classified as quick clays, with medium or high amounts of organic matter (O.M.); greater organic matter content was associated with increased sensitivity. In addition, it was understood that the intensity of clay sensitivity was higher with the increase in monovalent cations and the decrease in divalent cations such as Ca2+ and Mg2+, which must have been removed by the O.M. The soil pH reading ranged from high to very high acidity, an expected classification due to the increase in H+ concentration due to the O.M. All samples showed similar ζ values, with the lowest being 31.3 mV and 33.2 mV, which are still considered high, indicating that the soil colloids repel each other, forming a dispersed structure. Our results were consistent with similar reports in the literature; however, regionalized studies are necessary for a better understanding of the local peculiarities capable of influencing the profile of this soil.
Acesso aberto (Open Access)
Estudo da potencialidade da cinza da casca do murumuru, um resíduo agro industrial amazônico como filler ao concreto estrutural
(Universidade Federal do Pará, 2022-11-17) SOUZA, Milleno Ramos de; CORDEIRO, Luciana de Nazaré Pinheiro; http://lattes.cnpq.br/9126233381230999; https://orcid.org/0000-0001-7931-4042; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The use of agro-industrial waste in the partial replacement of cement in concrete has been the subject of research that analyzes the possible improvements in mechanical and physical properties and durability of the concrete, in addition to providing the use of mineral additions of natural origin or partial replacement in relation to the constituent materials of the composite, waste that would have inappropriate disposal, such as open-air landfills and burning. With this scenario, the study aims to research the use of murumuru husk ash (MHA), an agro-industrial waste generated specifically in the Amazon region as partial replacement of cement in structural concrete and evaluate the physical, chemical and mineralogical characteristics of the ash to act as filler in concrete, and its properties in the fresh and hardened state in concrete. With this purpose, the MHA underwent the physical-mechanical characterization tests such as specific mass, pozzolanic activity with Portland cement, pozzolanic activity with lime and BET test, also performing the mineralogical and chemical analysis of the ash. For concreting, a mix 1:1.6:2.4 (by mass) with water/cement ratio of 0.43 was considered, with replacement levels of 0%, 6%, 9% and 13% of the cement mass by MHA. After the dosage, the tests were performed on the concrete in its fresh and hardened state: slump test, specific mass, compressive strength (28 days), tensile strength in diametrical compression, water absorption by capillarities, specific mass in the hardened state, modulus of elasticity and morphological evaluation, through the Scanning Electron Microscope (SEM). Checking first the properties of concrete in the fresh state, it is evaluated that the insertion of the waste decreased the consistency and decreases the specific mass, except the concrete for the content of 6% that there was a 10% increase in the specific mass in relation to the concrete reference. Regarding the properties in the hardened state, the replacement by CCM showed an increase specifically in compressive and tensile strength in the 6% content at 28 days around 1% and 9% respectively, occurring a decrease in the contents of 9% and 13%. The results showed that there is a technical feasibility with partial replacement of 6% of MHA in cement, using plasticizer additive to improve workability
Acesso aberto (Open Access)
Gestão de resíduos da construção civil: um estudo de caso em Tucuruí-PA
(Universidade Federal do Pará, 2022-11-17) SOUSA, Fernanda dos Santos; CORDEIRO, Luciana de Nazaré Pinheiro; http://lattes.cnpq.br/9126233381230999; https://orcid.org/0000-0001-7931-4042; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The Civil Construction Industry (CCI) is guilty of impacts on the environment being one of the main sources of pollution today, especially with regard to the generation and disposal of waste in urban centres, this research was developed to diagnose and propose improvements in the management of Construction and Civil Construction Waste (CCW) in a small town, the case study was conducted in the city of Tucuruí-PA, a hub city in the Amazon region. To this end an investigation was conducted through online questionnaires with questions about management and management of CCW and was also performed identification of Irregular Disposal Points (IDP) through georeferencing using the Global Positioning System (GPS) and Qgis 3.16.6 software. After the analysis, we sought to suggest what would be the best improvement strategies for the management of waste from civil construction, through the current diagnosis of the management of CCW in the city. Through this research it was possible to perceive the most relevant points of management difficulty on the part of the Tucuruí Municipal Government (PMT), which are: absence of specific legislation for CCW, lack of environmental education on the subject, absence of supervision, in addition to the lack of management carried out by construction companies operating on construction sites, it was also possible to locate the IDPs and know the destination given to the CCW, in a market practically non-existent and without stimulus. The analyses contained in this diagnosis of the current situation of Civil Construction Waste management will enable actions to be recommended to improve it through public policies in the municipality of Tucuruí-PA, as well as in the region.
Acesso aberto (Open Access)
Metodologia de seleção de rotas de evacuação de emergência para caso de rompimento da UHE-Tucuruí
(Universidade Federal do Pará, 2019-01-30) GOTO, Raphaela Sobreira; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
Dams play an important role in Brazilian social and economic development. Although even when considered low risk, incidents involving dams can cause significant damage, and despite several potential costs resulting from material damages, the loss of a human life is the most meaningful in damage scale. Evacuation in case of disruption is a complex process that is the aggregated result of many factors, such as evacuation mode and characteristics of evacuation routes. In this context, the present work aims to determine a methodology for selecting emergency evacuation routes for the urban area of Tucuruí municipality located downstream of Tucuruí Hydroelectric Power Plant (UHE-Tucuruí), regarding the condition of a dam failure only. The methodology adopted is based on the optimization of evacuation routes, minimizing and/or excluding intersections along the way, this proposal follows an adaptation of route selection method developed by Zhang et al. (2016). The methodology was applied in four stages, the first was the division of the municipality into manageable zones according to the socioeconomic characteristics and road distribution, the second was the creation of the intersection table (adjacency) between the roads, the third was the determination of the exit routes, responsible for the displacement of the population to another municipalities and the fourth was the development of route selection method that has as a final product, a table of evacuation routes considering all possible exits of high risk area. The method establishes as the best route choice the one with the fewest intersections in the evacuation path. As a result, the methodology proved to be effective when applied in Tucuruí, generating possible evacuation routes within the entire urban perimeter of the municipality, providing affordability since it does not use software that requires a license and high application cost, being showed as a method of easy acceptability and communication among the population to be evacuated, providing time travel reduction, safer evacuation and traffic load balance between different exits.
Acesso aberto (Open Access)
Simulação numérica de derramamento de óleo na foz do rio Amazonas
(Universidade Federal do Pará, 2023-01-30) DEMONER, Sarana Castro; ABREU, Carlos Henrique Medeiros de; http://lattes.cnpq.br/9009261156099636; https://orcid.org/0000-0003-0904-8791; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The dynamics of rivers in the Amazon is predominantly linked to threats or natural events that may or may not trigger environmental damage. In March 2013 a large portion of soil slid into the interior of the Santana channel in Amapá, this abrupt mass movement took with it the Port of Santana and its respective facilities. The forensics findings identified a sensitive soil that had not previously been identified in Brazil. Due to the unusual behavior of the material on the shores of the Port of Santana, the new soil characteristics identified and because it is a port area, which houses several materials of great polluting potential, including bulk terminals, pipelines, the need arises to evaluate the behavior of a possible oil spill through hydrodynamic modeling. The software SisBaHiA® - Base System of Environmental Hydrodynamics was chosen to be used in the development of the models because it has a friendly interface and is already widespread in related lines of research. With the models and simulated scenarios, we identified the proportions of a new landslide accident involving these fuel reserves, the areas of the Santana channel that would be directly affected by the oil and what is the response time that the responsible institutions would have to trigger actions for mediation and containment of an accident of this proportion. Thus, the study seeks to obtain timely management mechanisms and decision-making about a possible accident.
Acesso aberto (Open Access)
O uso de Veículos Aéreos Não Tripulados (VANTs) para inspenções de segurança em barragens: estudo exploratório UHE Tucuruí
(Universidade Federal do Pará, 2021-05-28) EL BANNA, Kamila Dias Bernardes; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The main objective of this research is to verify the applicability of remote sensing by Unmanned Aerial Vehicles (UAVs), or popularly known as (drones) to aid in the safety of security in hydroelectric dams. It highlights the role and importance of technology as a means of innovation, for this application, as an exploratory study of the UHE Tucuruí. Some signs of deterioration or cracking, for example, can only be identified with visual inspections. For this reason, they are irreplaceable in dam safety control. In this context, the use of the UAV is very useful in these inspections, since its use makes this activity faster and safer, as it allows the verification of regions of the dam that are difficult to access, thus enabling full documentation of the dam's conservation status, in addition to the possibility of adapting sensors of different types and applicability, thus helping to provide more detailed information. The UAV, used for this research, satisfactory results for the evaluations to which it was exposed. Images with adequate quality and sequences were generated, so you can easily observe all the characteristics of the dam surface, thus providing a good support in the operation activities. In addition to supporting the dam safety assessment, the images generated can be gathered and used as a basis for other photographic surveys.