Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xv, 150 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 137-140).

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 357-378).

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [268]-284).

Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 151-159).

Orientador: Paulo César Lodi / Coorientador: Sandra Regina Rissato / Banca: Larissa Quartarol / Banca: Ricardo Molto Pereira / Resumo: As geomembranas de polietileno de alta densidade (PEAD) têm grande aplicação em obras que necessitam de estanqueidade, nas quais predominam processos difusivos de fluxo de líquidos ou gases. Face a essa importância e considerando o pouco estudo destinado a esse processo na literatura, este trabalho objetivou a avaliar o processo difusivo em geomembranas de PEAD, utilizando um equipamento previamente projetado, conforme estudos anteriores sobre o assunto. Dessa forma, foi possível avaliar o processo difusivo a que se submetem geomembranas de PEAD de 1mm de espessura quando em contato com chorume, gasolina e óleo diesel, simulando o processo em obras reais. Na avaliação do processo difusivo, buscou-se a determinação da concentração de íons cloreto, sulfato, nitrito, concentração de DBO (demanda bioquímica de oxigênio) na contaminação pelo chorume, além da determinação da concentração dos compostos BTX (benzeno, tolueno e xileno) na contaminação por combustíveis. Para tanto, foram utilizados o método de Mohr, ensaios de espectrofotometria e espectrometria de emissão atômica por plasma acoplado indutivamente, o método respirométrico para avaliação da DBO e a cromatografia gasosa para determinação de BTX nas amostras de água destilada/deionizada (livres de qualquer substância) retiradas do ensaio. Os equipamentos utilizados no ensaio de difusão, bem como as técnicas de medição, foram capazes de avaliar o processo de difusão pela geomembrana de PEAD. Os principais resultados mostra... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: High density polyethylene (HDPE) geomembranes have great application in works that require waterproofing, in which diffusive processes of liquid and/or gas flow predominate. Considering this importance and considering the little study destined to this process in the literature, this work aimed at evaluating the diffusive process in HDPE geomembranes by using equipment previously designed in previous studies on the subject. This way, it has been possible to evaluate the diffusive process to which 1mm-HDPE geomembranes are exposed when in contact with slurry, gasoline, and diesel oil, simulating the process in real works. In the evaluation of the diffusive process, the concentration of chloride, sulphate, nitrite, BOD (biochemical oxygen demand) concentration in the slurry, and the concentration of BTX compounds (benzene, toluene, and xylene) in fuel contamination have been determined. For this purpose, the Mohr method, spectrophotometry and inductively coupled plasma atomic emission spectrometry, the Respirometric method for BOD evaluation, and Gas Chromatography have been used to determine BTX in the samples of distilled/deionized water (free of any substance) removed from the test. The equipment used in the diffusion test, as well as the measurement techniques, have been able to evaluate the process of diffusion by the HDPE geomembrane. The main results show that there has been no contamination by chloride, sulphate, and nitrite ions, since the respective concentrations foun... (Complete abstract click electronic access below) / Mestre

In June 1994, a 150-m-long secondary road pavement section was built as part of the realignment of route 616 and 757 in Bedford County, Virginia to evaluate the performance of geosynthetically stabilized flexible pavements. The California Bearing Ratio (CBR) of the subgrade after construction was approximately 8%. The pavement section is was divided into nine individual sections, each approximately 15 m long. Sections one through three have a 100-mm-thick limestone base course (VDOT 21-B), sections four through six have a 150-mm-thick base course, and sections seven through nine have a 200-mm-thick base course. Three sections were stabilized with geotextiles and three with geogrids at the base course-subgrade interface. The remaining three sections were kept as control sections. One of each stabilization category was included in each base course thickness group. The hot-mix asphalt (HMA), SM-2A, wearing surface thickness was 78-90 mm. The outside wheel path of the inner lane was instrumented with strain gages, pressure cells, piezoelectric sensors, thermocouples, and moisture sensors. Section performances based on the instrumentation response to control and normal vehicular loading indicated that geosynthetic stabilization provided significant improvement in pavement performance. Generally, the measured pressure at the base course-subgrade interface for the geotextile-stabilized sections was lower than the geogrid-stabilized and control sections, within a specific base course thickness group. This finding agreed with other measurements, such as rut depth, ground penetration radar survey, and falling weight deflectometer survey. The control section (100-mm-thick base course) exhibited rutting that was more severe than the geosynthetically stabilized sections. Falling weight deflectometer back-calculation revealed consistently weaker subgrade strength for the geogrid-stabilized and control sections than for the geotextile-stabilized sections over the three year evaluation period. To quantitatively assess the extent of contamination, excavation of the first three sections in October 1997 revealed that fines present in the base course were significantly greater in the control and geogrid-stabilized section than in the geotextile-stabilized section. These findings led to the conclusion that the subgrade fine movement into the base layer when a separator is absent jeopardizes its strength. Further analysis of the field data showed that geotextile-stabilization may increase the service life of flexible secondary road pavements by 1.5 to 2 times. Finally, a new mechanistic-empirical flexible pavement design method for pavements with and without geosynthetics has been developed. Elasto-viscoelastic material characterization is used to characterize the HMA layer. The field results from Bedford County, Virginia project have been used to calibrate and validate the final developed design procedure. The concept of transition layer formed at the interface of base course and subgrade is also incorporated into the design approach. Powerful axisymmetric linear elastic analysis is used to solve the system of equations for mechanical and thermal loading on the pavement structure. Elasto-viscoelastic correspondence principle (EVCP) and Boltzman superposition integral (BSI) are used to convert the elastic solution to its viscoelastic counterpart and also to introduce the dynamic nature of vehicular loading. Pseudo-elastoplasticity is introduced into the problem by determining the extent of plastic strain using laboratory experimentation results and estimating the failure mechanisms, based on accumulated strains as opposed to the total strain (recoverable and non-recoverable). The pavement design approach presented in this dissertation is a hybrid of already existing techniques, as well as new techniques developed to address the visco-plastic nature of HMA. / Ph. D.

Experimental and analytical investigations were performed to evaluate the comparative performance of pavements with and without geosynthetic stabilization. This was accomplished by the testing of a total of 18 pavement sections which could be classified into four different types: one which was constructed without geosynthetics and which served as a control, and three which were stabilized with one of two geotextiles or a geogrid. The pavement sections were constructed to model a typical secondary road in Virginia which is constructed over a silty sand subgrade material. Loading of the pavement sections was accomplished through the use of a computer-controlled pneumatic system which delivered 80 lb/in2 (552 kPa) through a rigid plate at a frequency of approximately one-half Hertz. The resulting displacement of the pavement surface was monitored by an array of linear variable displacement transducers (LVDTs). The performance of each pavement section was evaluated using the American Association of State Highway and Transportation Officials (AASHTO) flexible pavement design method. Models based on empirical and mechanistic relationships were considered. A theoretical pavement section was also analyzed to assess the influence of the stiffness of a wearing course layer. An economic study was performed to assess the potential cost benefit of geosynthetic stabilization and recommendations have been made for additional research. / Master of Science

O uso de geossintéticos em vias permanentes tem tido grande aplicação em diversos países nas últimas décadas, principalmente em regiões onde o subleito não possui capacidade de suporte suficiente e/ou contamina a camada de lastro, acelerando a degradação da via. A Baixada Santista, região de grande importância nacional no que se refere ao escoamento de produtos de importação e exportação, é caracterizada por subleitos com grandes espessuras de solos orgânicos, saturados e com pouca resistência que elevam o número de intervenções na via e resultam em paralisações, reduções de velocidade e perda de produtividade. Este estudo tem como objetivo principal avaliar o comportamento estrutural e geométrico em vias permanentes contendo geocomposto, estando este posicionado em diferentes interfaces da estrutura (lastro-sublastro, lastro-plataforma e sublastro-plataforma). Para tanto, foram acompanhados dois trechos experimentais executados com e sem tal tecnologia, desde a construção, na linha 1 do Terminal Integrador Portuário Luiz Antonio Mesquita (TIPLAM), localizado em Santos (SP), e na linha 2 da via Piaçaguera - Raiz da Serra, também na Baixada Santista. Em ambos os trechos, foram realizadas avaliações geométricas, pelo monitoramento de recalques e variações quanto ao alinhamento. No segundo trecho, foi efetuada avaliação do comportamento estrutural por meio de ensaios in situ para levantamento de dados como deflexões (para cálculo do módulo de via). De maneira geral, as condições de plataforma e executivas dos trechos experimentais com geocomposto, além do curto período de monitoramento após a construção, foram desfavoráveis para verificar seu potencial de aplicação para reforço da via permanente. Em Piaçaguera, a utilização do geocomposto não indicou melhorias estruturais nem geométricas no período avaliado. Desta forma, para vias com baixo acúmulo de MTBTs, o geocomposto pode se constituir uma solução para longo prazo (ainda a se avaliar mais precisamente). Em relação ao TIPLAM, concluiu-se que a aplicação da geogrelha poderá não ocasionar redução no recalque total, independentemente da posição de instalação. Em contrapartida, utilizar o geocomposto na interface lastro/sublastro pode gerar melhorias geométricas no parâmetro de superelevação. Posicionando-se este em camadas mais profundas (sublastro/plataforma), podem ser gerados menores recalques diferenciais, entretanto essa conclusão ficou dificultada pelo comportamento da plataforma. De forma geral, essa pesquisa contribuiu para o conhecimento do uso de geocomposto em via permanente em diferentes condições de velocidade de operação, cargas transportadas e características geotécnicas. O estudo também abordou avaliações geométricas além das estruturais, que são alvo de poucos estudos de campo em nível nacional (sabendo-se da importância da geometria no intervalo entre manutenções e nível de segurança da via). / The use of geosynthetics in permanent ways has been widely applied in several countries in the last decades, mainly in regions where it can be witnessed the loss of subgrade bearing capacity during and after construction and/or the pumping of fines effect, which accelerates the degradation of the track. The soft soil foundation of Santos, a region of great national importance in terms of economics, is characterized by large deposits of saturated and low resistance soil layers that, once settled, increase the number of interventions on the railway and result in stoppages, speed control and loss of productivity. The main objective of this paper is to evaluate the structural and geometric behavior in permanent ways containing geocomposite, at different interfaces of the structure (ballast-sublast, ballast-platform and sub-platform). In order to do so, two experimental sections were carried out with and without such technology: line 1 of the Terminal Integrador Portuário Luiz Antonio Mesquita (TIPLAM), located in Santos (SP), and line 2 of the Piaçaguera - Raiz da Serra railway, also in the region of Santos. In both sections, geometric evaluations were carried out by monitoring settlements and variations in alignment. In the latter section, the structural behavior was evaluated through in situ tests to collect data such as deflections (for the calculation of the track modulus). In general, due to executive issues and platform characteristics of the experimental sections with geocomposite, alongside the short period of monitoring, it became adverse to verify the potential of such technology in means of reinforcing the track. In Piaçaguera, the use of the geocomposite did not indicate structural or geometric improvements during the evaluated period. Thus, for permanent ways with low MTBTs accumulation, the geocomposite can be a long-term solution (still to be evaluated more precisely). In relation to TIPLAM, it was concluded that the application of the geogrid may not cause reduction in total settlement, regardless of the installed position. In contrast, using the geocomposite at the ballast/sub-ballast interface can generate geometric improvements in the superelevation parameter. By positioning this in deeper layers (sub-ballast/platform), smaller differential settlements can be generated, however this conclusion was made difficult by the behavior of the platform. In general, this research contributed to the knowledge of the use of geocomposite in different railway conditions such as operation speed, transported loads and geotechnical characteristics. The study also addressed structural and geometric evaluations, which has not been addressed commonly oftenly in national studies, even though it is known the importance of geometry to dictate maintenance intervals and safety levels of railways.

The changing climate and damaging effects of CO2 on the environment has led to awareness throughout the construction industry of the need to deliver more sustainable solutions. The use of geosynthetics as a sustainable construction solution was demonstrated by the Waste and Resources Action Programme (WRAP) in a report entitled Sustainable Geosystems in Civil Engineering Applications (WRAP, 2010). The WRAP report presented a series of case studies in which geosynthetic solutions provided both cost and CO2 savings in comparison to non-geosynthetic solutions. However, in what is a huge field the report concentrated on specific areas relative to the calculation methods or on the potential construction applications. This EngD research built on this work by WRAP and aimed to establish a rigorous framework for the comparison of CO2 emissions between geosynthetic and non-geosynthetic solutions. This EngD research reviewed CO2 calculation methodologies and techniques to produce a rigorous framework that could be adopted in comparative CO2 studies between geosynthetic and non-geosynthetic solutions. It was demonstrated on three case studies looking at geosynthetics in the function of containment, drainage, and reinforcement, highlighting the possible CO2 benefits of employing geosynthetics. The development of the case studies and framework highlighted the need for accurate embodied carbon data. There was an absence of geosynthetic specific embodied carbon values in the commonly employed databases. The EngD research sought to address this and through some experimental work in collaboration with geosynthetic manufacturers calculated embodied carbon values for four types of geosynthetics.

The coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in both the short-term condition with its' undrained shear strength parameters, and the long-term drained condition. Results indicate that the combination of the techniques was found to have a possible increase of about 40% in the short-term condition and about 60% in the long-term condition of the factor safety associated with the slope. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection