DEAMB - Artigos publicados em periódicos

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Blending Linz–Donawitz and Blast Furnace slags with the Kambara reactor byproduct to improve their reuse in roadworks.
(2022) Schumacher, Aécio Guilherme; Gomes, Guilherme José Cunha; Schneider, Denise S. G.; Pires, Patrício José Moreira; Gomes, Ruan Gonçalves de Souza
The use of industrial byproducts as replacement of natural aggregates has been extensively investigated to design eco-friendly roads. One of the most examined byproducts for this purpose is steel slag. However, existing studies do not explore the blending of different slags to enhance the engineering performance of base layers. The applicability of Linz–Donawitz (LD), Blast Furnace (BF) and Kambara Reactor (KR) steel byproducts is evaluated as a single base layer for rural (unsurfaced) roads in Brazil. A series of laboratory experiments were performed to assess the characteristics of eight soil-byproduct mixtures with 50% and 75% byproduct contents, including new blends of LD/KR and BF/KR slags. Additionally, the most suitable mixture was proposed considering different performance indicators. Results demonstrate the coarse-grained, nonplastic and non-expansive nature of the byproducts, with CBR values higher than 100%. The more byproduct added to soil, the larger is the strength and the lower the expansion. The mixture with 75% of the proposed LD/KR blend and 25% of a clayey soil was considered as optimum, based on a trade-off between engineering properties, environmental impacts, and material costs. Findings and discussions are relevant to reduce waste stockpiles of steel companies, helping engineers and policy makers reuse blended slag byproducts.
A hybrid multi-step sensitivity-driven evolutionary polynomial regression enables robust model structure selection.
(2022) Gomes, Ruan Gonçalves de Souza; Gomes, Guilherme José Cunha; Vrugt, Jasper A.
Evolutionary Polynomial Regression (EPR) has found widespread application and use for model structure development in engineering and science. This hybrid evolutionary approach merges real world data and explanatory variables to generate well-structured models in the form of polynomial equations. The simple and transparent models produced by this technique enable us to explore, via sensitivity analysis, the robustness of the derived models. Yet, existing EPR frameworks do not make explicit use of sensitivity analysis in the selection of robust and high-fidelity model structures. In this paper, we develop a multi-step sensitivity-driven method which combines the strengths of differential evolution and model selection via Monte Carlo simulation to explore the input–output relationships of model structures. In the first step, our hybrid approach automatically determines the optimum number of terms of the polynomial equations. In a subsequent step, our algorithm explores the mean parametric response of each explanatory variable used in the mathematical formulation to select a final model structure. Finally, in our selection of the most robust mathematical structure, we take explicit consideration of the prediction uncertainty of the simulated output. We illustrate and evaluate our EPR method for different engineering problems involving modeling and prediction of the moisture content and creep index of soils. Altogether, our results demonstrate that the use of sensitivity analysis as an integral part of model structure search and selection will lead to robust models with high predictive ability.
Ferronickel slag as free‐draining rockfll dike material : a novel waste solution for mining regions.
(2022) Costa, João Paulo R.; Gomes, Guilherme José Cunha; Fernandes, Gilberto; Magarinos, Dario Mozzer; Fonseca, Alberto de Freitas Castro; Pires, Patrício José Moreira
Mining sites are vulnerable to erosion and siltation of rivers. While the construction of rockfill dikes can mitigate siltation, existing rockfill dikes are typically constructed with natural aggregates, whose mining, beneficiation, and transportation entail additional adverse impacts. In this paper, ferronickel slag (FNS) was investigated as a free-draining rockfill dike material to be used in nearby mining sites. A series of laboratory tests, including physical, environmental, durability, chemical and mineralogical analyzes, was executed to evaluate the engineering characteristics of this byproduct and its potential use in dikes. Results demonstrate that FNS is non-uniform with relatively low Los Angeles abrasion. Leaching and dissolution tests have not shown harm to the environment since the average concentrations of chemical elements existing in FNS were below the standard requirements. Accelerated weathering cycling tests with ethylene glycol further highlighted that the byproduct does not suffer premature disaggregation in the presence of water, thereby revealing that the material can be employed adequately under saturated condition. Findings suggest that the use of FNS in rockfill dikes represents a technically and environmentally feasible solution, while reducing the use of natural aggregates, avoiding the formation of stockpiles, preventing siltation in downstream fluvial networks and other adverse impacts.
Understanding the environmental impact of a mine dam rupture in Brazil : prospects for remediation.
(2019) Santos, O. S. H.; Avellar, F. C.; Alves, M.; Trindade, R. C.; Menezes, M. B.; Ferreira, M. C.; França, G. S.; Cordeiro, J.; Sobreira, Frederico Garcia; Yoshida, Maria Irene; Moura, P. M.; Scotti, M. R.
The rupture of the Fundão mine dam in Mariana municipality, Minas Gerais State, Brazil, spilled the tailings across the Doce River basin. These tailings, composed of residues discarded from the beneficiation of iron ore, are rich in SiO2 and Al2O3, as well as some ether amine compounds and NaOH. The aim of this study was to assess the distribution of these sediments, as well as their effect on the riparian zones reached, as compared with preserved sites. Sediment deposition in the river resulted in a morphological change from a meandering profile to a braided aspect. The nutrient and mineral content (P, K, Ca, Mg, Cu, Fe, Mn, Zn, and NO3−) and soil organic matter of the sediments were depleted, whereas NH4+, Na, and pH increased. A random presence of ether amines in the sediments was confirmed by quantitative and chromatographic analyses, with concentrations ranging from 0 to 57.8 mg kg−1; Na reached values as high as 150 mg kg−1. The impact of the dam tailings on biota was assessed by estimating total microbial biomass (phospholipid fatty acids), which were depleted in sediments relative to soils from preserved sites. Overall plant mortality, as well as a low resilience capacity, were also observed. Ether amines and Na present in the sediments had a strong toxic effect in the environment. Identification of these substances as the main impact factors will help guide future remediation efforts.
Effects of Psidium guajava L. leaves extract on blood pressure control and IL-10 production in salt-dependent hypertensive rats.
(2022) Braga, Daiane Cristina de Assis; Gomes, Paula Magalhães; Batista, Marcos Adriano Carlos; Souza, Jaqueline Aparecida de; Bastos, Juliana Cristina Santos Almeida; Dôres, Rosana Gonçalves Rodrigues das; Alzamora, Andréia Carvalho; Souza, Gustavo Henrique Bianco de; Moura, Sandra Aparecida Lima de; Silva, André Talvani Pedrosa da; Antunes, Vagner Roberto; Cardoso, Leonardo Máximo
Psidium guajava (guava) leaves extract displays anti-hypertensive properties by mechanisms not yet fully un- derstood. Here, we investigated whether sympathetic drive and immune signaling mechanisms are involved with the antihypertensive effect of the guava extract in a model of salt-dependent hypertension. Raw guava extract (rPsE) was characterized by colorimetric and UPLC-MS techniques. Two doses of rPsE (100 and 200 mg/kg) were evaluated for anti-hypertensive effect using a suspension system (PsE). Weaned male Wistar rats were put on a high-salt diet (HSD, 0.90 % Na+) for 16 weeks and received gavages of PsE for the last 4 weeks. Blood pressure (BP) was measured at the end of treatment in conscious rats. The neurogenic pressor effect was assessed by ganglionic blockade with hexamethonium. Autonomic modulation of heart rate was evaluated by spectral analysis. The effects of orally administered PsE on lumbar sympathetic nerve activity (LSNA) were assessed in anesthetized rats. Blood IL-10, IL-17A, and TNF were measured. The increased neurogenic pressor effect of HSD rats was reduced by PsE 100 mg/kg, but not by 200 mg/kg. PsE (200 mg/kg) administration in anesthetized rats produced a greater fall in BP of HSD rats compared to standard salt diet (SSD) rats. PsE hypotensive response elicited an unproportionable increase in LSNA of HSD rats compared to SSD rats. PsE (200 mg/kg) increased plasma concentrations of IL-10 but had no effect on TNF or IL-17A. Our data indicate that the antihypertensive effects of PsE may involve autonomic mechanisms and immunomodulation by overexpression of IL-10 in salt- dependent hypertensive rats.
Field-scale assessment of the unsaturated hydraulic properties of residual soils in southeastern Brazil.
(2022) Gomes, Ruan Gonçalves de Souza; Gomes, Guilherme José Cunha; Vargas Júnior, Eurípedes do Amaral; Genuchten, Martinus Theodorus van; Pinto, João T. M. G.; Rosa, Felipe A.
Field tests were carried out to estimate effective unsaturated soil hydraulic properties of layered residual soilsin Rio de Janeiro, southeastern Brazil. Data of this type are important for understanding the initiation of rainstorm-induced soil landslides, which often occur in the state of Rio de Janeiro as well as other areas having similar geologicsettings and climate conditions. Tests were carried out using a simplified field approach, referred to as the MonitoredInfiltration Test, which requires only a tensiometer to measure pressure heads below the wetting front, triggered by flowfrom a Mariotte bottle which maintains a constant pressure at the top edge of the soil profile. The data can then beanalyzed by numerical inversion using the HYDRUS-2D software package. The test is relatively fast since no steady-state flow conditions are needed, and versatile since the test can be carried out quickly on steep slopes with the help of amanual auger. Soil water retention and the unsaturated hydraulic conductivity functions were obtained for a range ofyoung, mature and saprolitic residual soils. The effective hydraulic properties of the distinct residual soil layers can bequite large, reflecting a need to provide a careful analysis of field-scale hydraulic heterogeneity in geotechnical analyses.
Influence of non-thermal plasma reactor geometry and plasma gas on the inactivation of Escherichia coli in water.
(2021) Cubas, Anelise Leal Vieira; Ferreira, Franciele Mendonça; Gonçalves, Daniela Borges; Machado, Marina de Medeiros; Debacher, Nito Angelo; Moecke, Elisa Helena Siegel
The inactivation of bacteria Escherichia coli (E. coli) by non-thermal plasma (NTP) was investigated using argon, air and 1:1 mixture of air/Ar as plasma gas on five different reactors. The experiments were carried out in triplicate in each reactor, using 60 mL of distilled water pre-inoculated with E.coli. The physical- chemical analysis of pH, conductivity, nitrite, nitrate and temperature were performed soon after of 10 min of NTP treatment. The microbiological analysis of E. coli inactivation was performed using 100 mL samples withdrawn from the plasma reactor after 10 min and compared with the positive and negative control test results. The best performance were achieved whit the NTP reactors working with the upper electrode in the gas phase using 1:1 air/Ar and air as plasma gas. The results are linked with the E. coli inactivation due to membrane rupture by the NTP discharge followed by the attack of the reactive species produced in the solution. The E. coli inactivation was only partial using argon as plasma gas and the direct barrier discharge reactors showed partial inactivation even when air was used as plasma gas.
Mobile science project : promoting active methodologies through environmental workshop in schools.
(2020) Cubas, Anelise Leal Vieira; Dutra, Ana Regina de Aguiar; Moecke, Elisa Helena Siegel; Magnago, Rachel Faverzani; Bianchet, Ritanara Tayane; Pilarski, Karina Suldovski; Machado, Marina de Medeiros
The main objective of this project is to investigate how active methodologies, based on workshops with environmental themes, can help high school students to learn subject matter in the area of the chemistry, physics and mathematics sciences and enhance their awareness of the importance of the preservation of the planet. In this study, 13 schools were visited in 4 years. During this time they participated in workshops that involved the use of residues to produce new materials, to provide environmental education regarding the reuse of waste and concepts embedded in the chemistry, physics and mathematics sciences. The results highlight that most of the students (98%) found the Mobile Science project interesting, 97% enjoyed participating in the workshops. Regarding the content of the workshops, 92% of the students answered positively; that is, the workshops were related and helped to understand the exact sciences. The Mobile Science project is part of the Unisul ́s actions aligned to sustainable development goals (SDGs), UN 2030 Agenda.
Oil extraction from spent coffee grounds assisted by non-thermal plasma.
(2020) Cubas, Anelise Leal Vieira; Machado, Marina de Medeiros; Bianchet, Ritanara Tayane; Hermann, Kênia Alexandra da Costa; Bork, Jonathan Alexsander; Debacher, Nito Angelo; Lins, Elisa Flores; Maraschin, Marcelo; Coelho, Daniela Sousa; Moecke, Elisa Helena Siegel
Coffee is one of the most popular beverages in the world and around 50% of the processed coffee beans becomes waste as spent coffee grounds (SCG). These SCG contain up to 20% of oil, which can be recovered and used in many different processes, such as biodiesel production, cosmetics and pharmaceuticals. The extracted oil contains large amounts of antioxidants, anti-inflammatory agents and immunomodulators, in addition to fatty acids that have excellent emollient and moist- urizing properties. It is therefore of interest to improve the oil extraction technique, to enhance the efficiency, reduce the extraction time and improve the quality of the oil extracted. Thus, in this study, a new technique for SCG oil extraction, using a non-thermal plasma technology as a pre-extraction procedure prior to Soxhlet extraction, was investigated, aiming to improve the extraction efficiency and oil quality. For comparison purposes, experiments were also carried out using an ultrasound pre-extraction procedure prior to Soxhlet extraction. It was observed that the use of pre-extraction with the plasma more than double the extraction yield compared with the Soxhlet extraction alone. Also, it increased the yield by around 30% compared with the use of ultrasound as the pre-extraction procedure. Analysis of the oil extracted by GC–MS showed that the quality of the oil composition was maintained. Also shows an increase in the antioxidant potential, which can prevent the harmful effects of ultraviolet (UV) radiation on the skin, due to their antioxidant, anti-inflammatory and immunomodulatory properties. The SEM images showed significant changes in the walls of the polyhedral cells of the spent coffee grounds after non-thermal plasma pre-treatment.
Applicability of bacterial cellulose in cosmetics : bibliometric review.
(2020) Bianchet, Ritanara Tayane; Cubas, Anelise Leal Vieira; Machado, Marina de Medeiros; Moecke, Elisa Helena Siegel
The search for innovation and new approaches to mitigate environmental impact encourages the cosmetic industry to explore new methodologies and materials. Bacterial cellulose has been the focus of research because it has high biocompatibility, skin adhesion, and water retention, in addition to being a sustainable alternative material. This review paper explored the perspectives emerging in the scientific literature on the use of bacterial cellulose in cosmetics. This bibliometric review was performed using four databases along with three software programs to obtain a more complete analysis. The search identified 18 articles related to the topic. Because the highest number of articles was published in the year 2019, it was estimated that more publications will appear in the near future. Studies have demonstrated the potential for the use of bacterial cellulose in face masks for the delivery of active compounds and increased skin hydration, and it can also act as an emulsion stabilizer.
Gestão empresarial de emergências : uma análise dos Planos de Ação Emergencial de barragens de alto dano potencial associado instaladas no município de Ouro Preto/MG.
(2020) Paiva, Camilla Adriane de; Prado Filho, José Francisco do
O presente trabalho analisou o conteúdo dos Planos de Ação Emergencial (PAE), documento exigido pela Lei Federal no 12.334/10, a Política Nacional de Segurança de Barragens, das barragens de alto Dano Potencial Associado (DPA) instaladas município de Ouro Preto, MG. Para tanto utilizou-se o como método de estudo a análise de conteúdo documental dos PAE arquivados nos órgãos responsáveis. Após acesso aos PAEs, verificou-se na época que das onze barragens de DPA instaladas em Ouro Preto, apenas sete possuíam planos protocolizados na Defesa Civil do município. Ao se analisar o conteúdo dos Planos (PAE), viu-se que, de modo geral, todos apresentam os itens mínimos exigidos por lei, mas a maioria deles apresenta estudo deficiente de cenários hipotéticos em eventual ruptura da estrutura de contenção, problema que que se espera ser melhor estudado com o lançamento da Portaria DNPM no 70.389 de 2017. Por fim, viu-se que após grandes desastres como o da barragem de Fundão da Samarco Mineração, há uma tendência de maior concretização, valorização e efetivação do PAE como principal instrumento para adoção de medidas emergenciais por parte dos proprietários de barragens em eventuais situações de risco e desastres.
Incentivos financeiros municipais visando a proteção ambiental : análise da experiência em Ouro Preto, MG.
(2020) Gomes, Amanda Aparecida; Prado Filho, José Francisco do
Um importante instrumento de gestão ambiental, na categoria de instrumentos econômicos, se concretiza nos denominados incentivos financeiros municipais. Eles objetivam estimular a população a reduzir o consumo dos recursos naturais e energia, visando minimizar os impactos ambientais locais, concedendo, dentre outros benefícios, descontos no Imposto Predial e Territorial Urbano (IPTU) para proprietários de imóveis que adotam ações de sustentabilidade ambiental. Neste contexto, este estudo avaliou a participação da população no programa “Quem preserva paga menos”, estabelecido pela Lei Complementar No 113, de 27 de dezembro de 2011, do município de Ouro Preto – MG. O trabalho avaliou por meio de entrevistas semi-estruturadas o conhecimento de tal incentivo pela população ouropretana. Para tanto, foram aplicados 200 questionários e estudados requerimentos de solicitação para participação no Programa arquivados na Secretaria Municipal de Meio Ambiente da Prefeitura (SEMMA-OP). Os resultados da pesquisa mostraram que, apesar do programa já ter mais de sete anos de funcionamento, cerca de 69% dos entrevistados não conhecem esse tipo de incentivo financeiro- ambiental local, enquanto que, da parcela que conhece o instrumento (31%), apenas 27% participam. Os dados revelam falta de conhecimento do programa principalmente devido as fragilidades de divulgação do mesmo no âmbito da população de Ouro Preto.
Construção da equação do Indicador de Salubridade Ambiental (ISA/OP) da cidade de Ouro Preto (MG) para o gerenciamento do saneamento municipal urbano.
(2020) Teixeira, Diogo Araújo; Prado Filho, José Francisco do; Santiago, Aníbal da Fonseca
O Indicador de Salubridade Ambiental (ISA) foi criado em 1999 objetivando medir o nível de salubridade ambiental dos municípios paulistas e usá-lo como ferramenta para o gerenciamento do saneamento ambiental municipal. Para avaliar outros locais, os pesos e indicadores que estão na formulação original do ISA podem ser adaptados às características da localidade a ser avaliada – o que é sugerido no manual de criação. Todavia, escolher e a atribuir os pesos dos indicadores que compõe o ISA é um desafio. Há estudos que arbitram indicadores e pesos conforme o julgamento do autor. Em outros, as escolhas são baseadas na revisão bibliográfica e literatura. Outros optam pelo método Delphi – apenas citam a metodologia, sem apresentar detalhes da utilização. O método Delphi baseia-se em repetidas consultas (rodadas) a um grupo de especialistas buscando obter consenso entre eles sobre determinado tema, obtendo uma opinião consolidada do grupo como resposta. O objetivo deste estudo foi utilizar o referido método como ferramenta para a construção da fórmula do ISA para a cidade de Ouro Preto - Minas Gerais (ISA/OP) e detalhar a aplicação da metodologia. Duas rodadas de perguntas foram feitas via e-mail para um grupo contendo 40 especialistas em salubridade ambiental urbana. O consenso foi obtido estatisticamente ao final da segunda rodada. Considera-se o emprego dessa metodologia adequado para a criação do ISA/OP, tornando-o um importante instrumento de planejamento e gestão ambiental, capaz de subsidiar tomadores de decisões da administração municipal no que tange à avaliação dos componentes socioambientais analisados na formulação do ISA/OP.
Restrição do uso das águas da bacia hidrográfica do rio Matipó devido à contaminação microbiológica.
(2020) Reis, Deyse Almeida dos; Nascimento, Laura Pereira do; Marques, Lilian de Souza; Oliveira, Edilson Gonçalves de; Ferreira, Clovis de Souza; Chagas, Igor Aparecido Santana das; Roeser, Hubert Mathias Peter; Santiago, Aníbal da Fonseca
O presente estudo foi realizado na bacia hidrográfica do Rio Matipó, um afluente do Rio Doce, em Minas Gerais – Brasil. O principal objetivo foi avaliar a contaminação microbiológica das águas da bacia devido à influência da atividade humana. Para tal, foram realizadas amostragens de água em 25 estações de monitoramento situadas ao longo do curso hídrico em períodos sazonais distintos. Essas amostragens possibilitaram mensurar variáveis químicas e microbiológicas das águas. A análise dos dados obtidos permitiu observar a limitação dos usos da água da bacia hidrográfica pelo fato de estar contaminada com microrganismos, alguns potencialmente patogênicos. Os impactos ambientais verificados na bacia hidrográfica, como criação de animais nas margens e, principalmente, lançamento de esgoto sanitário sem tratamento, foram os principais fatores que interferiram na limitação dos usos da água para balneabilidade e para o abastecimento público.
A dual search‐based EPR with self‐adaptive ofspring creation and compromise programming model selection.
(2021) Gomes, Guilherme José Cunha; Gomes, Ruan Gonçalves de Souza; Vargas Júnior, Eurípedes do Amaral
Evolutionary polynomial regression (EPR) is extensively used in engineering for soil properties modeling. This grey-box technique uses evolutionary computing to produce simple, transparent and well-structured models in the form of polynomial equations that best explain the observed data. A key task is then to determine mathematical structures for modeling physical phenomena and to select the optimal EPR model. This requires an algorithm to search through the model structure space and successfully produce feasible solutions that honor a set of statistical metrics. The complexity of EPR models increases greatly, however, with the number of polynomial terms used to tune these models. In this paper, we propose an alternative EPR for modeling complex soil properties. We implement a dual search-based EPR with self-adaptive ofspring creation as model structure search strategy and couple a compromise programming tool to select a model that is preferred statistically relative to models with diferent polynomial terms. We illustrate our method using real-world data to improve predictions of optimal moisture content and creep index for soils. Our results demonstrate that the models derived using the proposed methodology can predict soil properties with adequate accuracy, physical meaning and lower number of parameters and input variables.
Bayesian inference of rock strength anisotropy : uncertainty analysis of the Hoek–Brown failure criterion.
(2021) Gomes, Guilherme José Cunha; Gaona, John Harry Forero; Vargas Júnior, Eurípedes do Amaral; Vrugt, Jasper A.
Strength properties of most sedimentary and metamorphic rocks are known to vary with direction. Knowledge of this so-called rock anisotropy is of utmost importance for reliability analysis and engineering design. The purpose of this paper is twofold. First, we propose a formulation of the Hoek–Brown (HB) failure criterion, which calculates strength anisotropy using a non-uniform scaling of the stress tensor. We use two scaling factors, CN and CS , to link the orientation of the anisotropy planes with the loading direction. As we assume isotropic parameters for intact rock, our HB model formulation is relatively easy to use and has the additional advantage that it does not demand any modifications to the HB failure criterion. Second, we embed our HB model formulation in a Bayesian framework and illustrate its power and usefulness using experimental data of anisotropic rock samples published in the literature. Results demonstrate that our HB model formulation predicts accurately measured peak strengths of rocks with different degrees of anisotropy, confining stresses and anisotropy orientations. The uncertainty in peak strength of anisotropic rocks can be quite large, reiterating the need for an explicit treatment of strength anisotropy uncertainty in rock mechanics studies. The Bayesian methodology is general-purpose, and, as such, can help better inform geotechnical engineers, contractors and other professionals about rock conditions and design reliability and assist decision makers in determining the overall risks of engineering structures.
A cross-anisotropic elastoplastic model applied to sedimentary rocks.
(2020) Gaona, John Harry Forero; Gomes, Guilherme José Cunha; Vargas Júnior, Eurípedes do Amaral; Falcão, Flávia de Oliveira Lima; Velloso, Raquel Quadros
Strength and deformability properties of sedimentary rocks are difficult to characterize as these geomaterials show anisotropic mechanical behavior, which cannot be adequately evaluated by an isotropic constitutive model. This essay proposes a cross-anisotropic elastoplastic model to evaluate stress–strain relationships of sedimentary rocks. The approach couples the twelve-parameter Lade–Kim isotropic model with a non-uniform scaling of the stress tensor and includes two scaling parameters that link the orientation of the bedding planes with the loading direction. The anisotropic model parameters can be conveniently determined using Bayesian analysis. We illustrate our method using triaxial tests on a variety of confining stresses and bedding plane orientations for a travertine and a Tournemire shale. Our results demonstrate that the predicted maximum deviatoric stresses and the simulated stress–strain curves are shown to be in good agreement with the measured data.
Toward improved performance of unpaved roads : laboratory tests and field investigation of a soil-byproduct base layer.
(2020) Magalhães, Adair José de; Gomes, Guilherme José Cunha; Pires, Patrício José Moreira
In this study, the performance of two steel slag byproducts is investigated to produce mixtures for base layers of unpaved roads. The basic physical properties including Atterberg limits, grain size distribution, California bear- ing ratio and expansion tests of eight different mixtures of soil-byproduct are investigated in laboratory to understand the engineering properties of the mixtures. The byproducts are mixed in different proportions from 50% to 80% by weight with a local (clayey) subgrade soil. Subsequently, two selected mixtures are used to build an experimental road section along an unsurfaced road. Results demonstrate that the gradation and strength of the samples satisfy the requirements for base layers. Furthermore, the mix- tures are shown to be of low-plasticity at higher byproduct content and non-expansive. Field investigations show that 12 roller passes at the stan- dard Proctor and 14 at the intermediate Proctor are enough to reach 100% of the degree of compaction.
Modelagem da susceptibilidade de escorregamentos utilizando o método de pesos de evidência em uma região montanhosa de clima tropical.
(2021) Araújo, João Paulo de Carvalho; Barella, Cesar Falcão; Fernandes, Nelson Ferreira
Escorregamentos são fenômenos naturais que ocorrem em regiões montanhosas e podem causar grandes catástrofes socioeconômicas. A identificação das áreas susceptíveis a escorregamentos é uma etapa essencial da gestão de riscos e auxilia a implementação de projetos que visam mitigar, ou mesmo evitar os danos causados por estes eventos. Este trabalho avalia a susceptibilidade a escorregamentos translacionais pelo método estatístico bivariado de Pesos de Evidência, assim como o controle individual de oito fatores predisponentes em duas bacias piloto no maciço da Tijuca, na cidade do Rio de Janeiro (RJ). Cinco modelos de susceptibilidade foram produzidos pela combinação dos fatores predisponentes e tiveram sua capacidade preditiva testada pelo cálculo da área abaixo da curva (AAC). A maior parte dos escorregamentos mapeados ocorreram nas cabeceiras de drenagem das bacias piloto, nas encostas com ângulo entre 34° e 51°, sustentadas principalmente por intrusões graníticas e coberta por floresta preservada. O mapa final possui cinco classes de susceptibilidade e demonstrou ser eficaz na previsão dos escorregamentos. O método é robusto e evita subjetividades, ao mesmo tempo que é bastante versátil. Apesar de pouco utilizado no Brasil, o método é apropriado ao contexto de complexa geodiversidade e carência de dados geotécnicos, em escala regional e local.
Discriminant analysis as an efcient method for landslide susceptibility assessment in cities with the scarcity of predisposition data.
(2021) Eiras, Cahio Guimarães Seabra; Souza, Juliana Ribeiro Gonçalves de; Freitas, Renata Delicio Andrade de; Barella, Cesar Falcão; Pereira, Tiago Martins
The city of Ouro Preto, which is located in the state of Minas Gerais, Brazil, has a long history of mass movements infuenced by the regional geology, geomorphology, and anthropic activities, which have resulted in harmful consequences to the population. How- ever, most of the studies conducted in the region are qualitative and are directly dependent on the experience specialists. The aim of this study was to analyse the landslide suscepti- bility in the urban region of Ouro Preto quantitatively by using discriminant analysis. The landslide inventory was obtained by using unmanned aerial vehicle images and feldwork. ArcGIS 10.6 and R 3.5.1 software were used, and the following landslide predisposing fac- tors were considered: slope angle, slope aspect, profle curvature, and topographic wetness index (TWI). As geological and geotechnical data are still scarce in the interior of Brazil, we only used data derived from topography to determine the efectiveness of these factors for analysing landslide susceptibility. The slope angle proved to be the factor that most diferentiated unstable from stable terrain, followed by TWI. The other parameters were not as efective in diferentiating the stability conditions. The model efciency was 88.6%, the specifcity was 93.3%, and the sensitivity was 85.0%. Also, the prediction and success curve were used to evaluate the accuracy of the proposed landslides model, by using the area under the curve (AUC) criteria. It was shown that the AUC values 0.851 for testing and 0.838 for training indicate that the developed model provides an excellent prediction. The main contribution of this work is the demonstration of the efectiveness of using easily accessible data (derived from topography) for analysing landslide susceptibility with amultivariate statistical method. This method can contribute valuable information to urban planning eforts in cities without the need for robust data.

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