O comportamento de solos reforçados depende amplamente da interação entre o solo e o reforço, baseado nas solicitações que o conjunto experimentará ao longo da sua vida útil. Tal interação é comumente caracterizada através de ensaios normatizados como o de arrancamento, que buscam simular as solicitações a que o conjunto estará sujeito. Porém, algumas estruturas reforçadas experimentam ações cíclicas de cargas móveis consideráveis, que dificilmente tem seu comportamento representado nestes ensaios comuns. Diante disso, esta pesquisa buscou aperfeiçoar o equipamento de ensaios cíclicos da Escola de Engenharia de São Carlos EESC-USP, a fim de realizar ensaios cíclicos em diferentes tipos de solos (uma areia, um silte argiloso e uma brita graduada simples), reforçados com uma geogrelha de poliéster comumente utilizada para reforço de base de pavimentos. Após esta etapa se iniciaram os ensaios de arrancamento nos solos, fornecendo parâmetros para a realização dos ensaios cíclicos. No arrancamento a areia apresentou ganho de resistência com o aumento da tensão confinante, e os maiores deslocamentos, já o silte e a brita não sofreram influência deste aumento. O comportamento cíclico causou desconfinamento da areia e degradação do reforço na brita, apresentando o comportamento mais estável no silte. Durante os ensaios o reforço apresentou grandes deformações conforme solicitado, o que contribuiu para os valores de módulos de resiliência abaixo dos descritos na literatura, que utiliza corpos de prova curtos e diferentes níveis de tensões. Nos ensaios cíclicos a areia variou seu módulo relativamente pouco com as variações de tensão confinante e cisalhante, o silte foi mais sensível à variação da cisalhante e a brita variou igualmente com as duas. / The behavior of reinforced soils depends largely on the interaction between soil and reinforcement, based on requests that the group will experience throughout its service life. Such interaction is commonly characterized by standardized tests such as the pullout, which seek to simulate the stresses to which the group is subject. However, some reinforced structures experience cyclic loads by considerable moving loads, that their behavior is hardly represented in these common tests. Thus, this research sought to improve the equipment of cyclic tests of the School of Engineering of São Carlos EESC-USP, in order to perform cyclic tests on different types of soil (one sand, clayey silt and a simple graded gravel), reinforced with one polyester geogrid commonly used for reinforcing pavements base. After this step began the pullout tests on soils, providing parameters for the realization of the cyclic tests. In the pullout tests, the sand had resistance gain with confining tension increasing and greater displacements, already silt and gravel not affected by this increase. The cyclical behavior caused deconfinement of sand, and the gravel causes degradation of reinforcement, with the more stable behavior on silt. During the test, the reinforce presented large deformations as requested, which contributed to the values of resilience modules below in the literature, which uses specimens shorter and different tension levels. In the cyclic tests the sand modulus varied relatively little with confining pressure and shear variations, the silt was more sensitive to the variation of shear and gravel also varied with both.

Welded wire mesh has been used in the past as soil reinforcement in the construction of reinforced soil embankments. Involved in the design of these embankments is the external and internal stability. The internal stability has two failure mechanisms; tension failure and pullout failure of the welded wire mesh. This paper presents the results of laboratory tests on different sizes of welded wire mats embedded in different types of soils. These tests were performed on mats that are much larger than in previous tests. These tests measured the pullout resistance as a function of the number of embedded wires, the diameter of the wire, and the overburden pressure. This data is plotted to allow design of reinforced soil embankments in various types of soils and to compare the results with theoretical relationships.

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The enrollment of English as a Second Language (ESL) students from Pre-K through Grade 12 increased 65% over a 10-year period from the 1993-1994 to the 2003-2004 school year. The number of ESL students in 2003-2004 was 10.1% of the total public school enrollment. ESL students are placed in different educational programs. Pullout programs have served low readers including English language learners (ELL). In the last 10 years, inclusion programs have gradually replaced pullout programs in some states. Little research has been conducted on the effectiveness of ESL programs on reading achievement. This study compared the improvements in reading of Grades 1 and 2 ESL students over two consecutive school years (2004-2006) in pullout programs and inclusion programs in a Midwest inner-city school district with a large population of ESL students. Additionally, strengths and weaknesses of each program as described by teachers were compared. Furthermore, teachers? frustrations and struggles in each program were examined as well. The results of descriptive analysis and ANCOVA indicate that type of program (pullout or inclusion) did not result in a statistical difference in ESL students? reading achievement. Two models for each program were found to be used in the school district. The results indicate that the guided reading approach was used in both programs and ESL students were instructed in small group setting, but the inclusion programs used longer instruction time than the pullout program. Scheduling in inclusion programs was easier than in pullout program. Teachers did not feel overloaded in either program. Interviewed teachers report students did not feel bothered by being pulled out; instead, they felt honored. Paraprofessionals were used in the classrooms to lead small groups during the reading block in inclusion programs, but they were sent to the classrooms to work with ESL students during the time of math, science, or social study in pullout programs. Teachers in inclusion programs did not worry about students missing anything, and every student?s needs were met. Collaboration and communication between teachers and resource teachers were the key to successfully operating either program, but they did not happen effortlessly.

This thesis presents results of an experimental investigation to characterize single straight steel fiber pullout in Ultra-High Performance Concrete (UHPC). Several parameters were explored including the distance of fibers to the edge of specimen, distance between fibers, and fiber volume in the matrix. The pullout load versus slip curve was recorded, from which the pullout work and maximum pullout load for each series of parameters were obtained. The curves were fitted to an existing fiber pullout model considering bond-fracture energy, Gd, bond frictional stress, 𝛕0, and slip hardening-softening coefficient, 𝜷. The representative load-slip curve characterizing the fiber pullout behavior will be implemented into a computational modeling protocol, for concrete structures, based on Lattice Discrete Particle Modeling (LDPM). The parametric study showed that distances over 12.7 mm from the edge of the specimen have no significant effect on the maximum pullout load and work. Edge distances of 3.2 mm decreased the average pullout work by 26% and the maximum pullout load by 24% for mixes with 0% fiber volume. The distance between fibers did not have a significant effect on the pullout behavior within this study. Slight differences in pullout behavior between the 2% and 4% fiber volumes were observed including slight increase in the maximum pullout load when increasing fiber volume. The suggested fitted parameters for modeling with 2% and 4% fiber volumes are a bond-fracture energy value of zero, a bond friction coefficient of 2.6 N/mm² and 2.9 N/mm² and a slip-hardening coefficient of 0.21 and 0.18 respectively. / Master of Science

objetivo principal do trabalho é determinar a capacidade última de tração (arrancamento) de uma fundação com solo tratado no topo a partir de uma modelagem numérica com o programa computacional Abaqus a partir dos ensaios feitos em solos tratados. Os modelos numéricos foram feitas a partir dos ensaios ao arrancamento em solos tratados por Ruver, 2011 e Girardello, 2014 para um aterro de areia (proveniente da cidade de Osório/RS) e areia com fibra (monofilamentos de polipropileno). Foi feito um modelo numérico inicial com as propriedades geotécnicas de ensaios feitos em laboratório e campo para depois fazer um ajuste do modelo com os ensaios ao arrancamento. Foi avaliado o modelo numérico de areia e areia-fibra para as tensões iniciais, deslocamentos inciais e a etapa geostatic porque não só é ter bons resultados nas figuras do ajuste, mas se ter um modelo numérico bem feito que apresente um comportamento próximo da realidade numericamente. Foram avaliados os benefícios gerados pelo aumento da capacidade de carga de fundações escavadas e reaterradas com areia fina e homogênea, areia-fibra, avaliando sua influência geotécnica (coesão, ângulo de atrito e módulo de elasticidade) a partir de uma análise paramétrica. Foi feito um método de dimensionamento e estimativa da capacidade ao arrancamento para um aterro com areia e areia-fibra a partir das metodologias internacionais e os modelos numéricos. / The main objective of the work is to determine the ultimate traction (pullout) capacity of a foundation with treated soil at the top from a numerical modeling with the Abaqus computational program from the tests on treated soils. The numerical models were made from the pullout tests on soils treated by Ruver, 2011 and Girardello, 2014 for a sand dump (from the city of Osório / RS) and sand with fiber (polypropylene monofilaments). An initial numerical model was made with the geotechnical properties of laboratory and field tests to later calibrate the model with the pullout tests. It was evaluated the numerical model of sand and sand-fiber for the initial stresses, displacements and the geostatic step because not only is it to have good results in the figures of the calibration, but it is necessary to have a well-designed numerical model that presents behavior close to reality numerically. It was evaluated the benefits generated by the increase of the load capacity of excavated foundations and recovered with fine sand and homogeneous, sand-fiber, evaluating its geotechnical influence (cohesion, friction angle and modulus of elasticity) from a parametric analysis. A method of dimensioning and estimation of the pullout capacity for a backfill with sand and sand-fiber was done from the international methodologies and the numerical models.

objetivo principal do trabalho é determinar a capacidade última de tração (arrancamento) de uma fundação com solo tratado no topo a partir de uma modelagem numérica com o programa computacional Abaqus a partir dos ensaios feitos em solos tratados. Os modelos numéricos foram feitas a partir dos ensaios ao arrancamento em solos tratados por Ruver, 2011 e Girardello, 2014 para um aterro de areia (proveniente da cidade de Osório/RS) e areia com fibra (monofilamentos de polipropileno). Foi feito um modelo numérico inicial com as propriedades geotécnicas de ensaios feitos em laboratório e campo para depois fazer um ajuste do modelo com os ensaios ao arrancamento. Foi avaliado o modelo numérico de areia e areia-fibra para as tensões iniciais, deslocamentos inciais e a etapa geostatic porque não só é ter bons resultados nas figuras do ajuste, mas se ter um modelo numérico bem feito que apresente um comportamento próximo da realidade numericamente. Foram avaliados os benefícios gerados pelo aumento da capacidade de carga de fundações escavadas e reaterradas com areia fina e homogênea, areia-fibra, avaliando sua influência geotécnica (coesão, ângulo de atrito e módulo de elasticidade) a partir de uma análise paramétrica. Foi feito um método de dimensionamento e estimativa da capacidade ao arrancamento para um aterro com areia e areia-fibra a partir das metodologias internacionais e os modelos numéricos. / The main objective of the work is to determine the ultimate traction (pullout) capacity of a foundation with treated soil at the top from a numerical modeling with the Abaqus computational program from the tests on treated soils. The numerical models were made from the pullout tests on soils treated by Ruver, 2011 and Girardello, 2014 for a sand dump (from the city of Osório / RS) and sand with fiber (polypropylene monofilaments). An initial numerical model was made with the geotechnical properties of laboratory and field tests to later calibrate the model with the pullout tests. It was evaluated the numerical model of sand and sand-fiber for the initial stresses, displacements and the geostatic step because not only is it to have good results in the figures of the calibration, but it is necessary to have a well-designed numerical model that presents behavior close to reality numerically. It was evaluated the benefits generated by the increase of the load capacity of excavated foundations and recovered with fine sand and homogeneous, sand-fiber, evaluating its geotechnical influence (cohesion, friction angle and modulus of elasticity) from a parametric analysis. A method of dimensioning and estimation of the pullout capacity for a backfill with sand and sand-fiber was done from the international methodologies and the numerical models.