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Orientador: Mauro Augusto Demarzo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-07T08:31:00Z (GMT). No. of bitstreams: 1 Tacitano_Marcelo_D.pdf: 8426940 bytes, checksum: 2052cac2233a599ef85b5133ca5ceec4 (MD5) Previous issue date: 2006 / Resumo: As estruturas de contenção de valas, normalmente de madeira, aço ou concreto, podem ser constituídas por estacas-prancha, estacas com pranchões, estacões, paredes-diafragma entre outras e precisam ser dimensionadas, de que maneira que atinjam adequadamente os requisitos de funcionalidade, exeqüibilidade, segurança e economia a que se propõem. Dentre os métodos para o seu dimensionamento é possível enquadrá-los em três grandes grupos. Os Métodos Empíricos que se baseiam em resultados de medidas experimentais, os Métodos Semi-Empíricos que admitem como carregamento um diagrama de pressões para ambos os lados da parede, em cada fase de escavação, pressupondo o tipo de grandeza dos deslocamentos e considerando as estroncas e tirantes como apoios fixos e, finalmente, os Métodos Analíticos, que levam em conta as características de resistência e rigidez da estrutura e do maciço e possibilitam o cálculo evolutivo em que os esforços e deslocamentos das fases anteriores são efetivamente levados em conta nos cálculos das fases seguintes. Inicialmente uma ampla revisão bibliográfica sobre os métodos de cálculo de paredes de contenções é apresentada. Após, este trabalho adota como foco de estudo o Modelo de Winkler, através de Método Analítico Unidimensional, que tem sua aplicação prática pela construção do programa CEDEVE (Cálculo Evolutivo de Deslocamentos e Esforços em Valas Escoradas). Este método assimila a parede como uma viga de largura unitária, sendo o solo modelado como molas de comportamento elasto-plástico perfeito incluindo histerese. Estroncas e tirantes, de comportamento elástico, com ou sem esforços iniciais, podem ser introduzidos na estrutura. As ações sobre a estrutura advêm dos empuxos de solo, de água e das eventuais sobrecargas presentes na superfície. Os cálculos são conduzidos de acordo com as fases de escavação, retirando-se as ações (empuxos) e molas correspondentes ao solo escavado e introduzindo-se as estroncas e/ou tirantes a serem instalados, sendo que os esforços e deslocamentos ocorridos nas fases anteriores são devidamente considerados nos cálculos das fases seguintes. O reaterro, quando existir, também é considerado. Um diferencial importante do método de cálculo proposto com relação a outros similares é a possibilidade da inclusão dos efeitos de temperatura nos cálculos dos deslocamentos e esforços, sendo que tais efeitos térmicos podem ser considerados sobre as estroncas, o que promove a tendência de seu alongamento, que sendo parcialmente impedido, gera conseqüentes esforços de compressão e também na própria parede de contenção através de gradientes que induzem flexão, e, portanto também influindo nos esforços sobre o sistema de estroncas. Um estudo prático e numérico é conduzido com o intuito de se validar e verificar o programa CEDEVE, primeiramente testando seus resultados com o programa SAP 2000 e, após, comparando os resultados por ele gerados com vários outros programas disponíveis (SPW2003, DEEP e ESTWIN). O efeito da temperatura sobre as estroncas, calculado pelo CEDEVE, é comparado com alguns resultados de instrumentações disponíveis na bibliografia consultada. Além disso, um estudo comparativo com alguns Métodos Empíricos e Semi-Empíricos é conduzido. De uma forma geral, é possível concluir que o Modelo de Winkler utilizado na modelagem do problema gera resultados satisfatórios e sua relação custo benefício é bastante atraente na análise de paredes de contenção / Abstract: The retaining structures, usually of wood, steel or concrete, can be constituted by sheet pile wall, piles with lagging, ¿in cast¿ pile walls and diaphragm walls among others and need to be designed, so that they reach the requirements about functionality, execution, safety and economy an appropriate way. It is possible divide the design methods in three great groups. The Empirical Methods that has been based on results of experimental measures, the Semi-Empirical Methods that admit as loading a diagram of earth pressures for both sides of the wall, in each excavation phase, presupposing the displacements and considering the struts and anchorage as fixed supports and, finally, the Analytical Methods that take into account the characteristics of strength and stiffness of the structure and soil and they make possible the evolutionary calculation of internal efforts (strut forces, bending moments and shear forces) as well as the displacements, so the previous phases are taken indeed into account in the calculations of the following phases. Initially a wide bibliographical revision on the methods of calculation of retaining structures is presented. After that, this work adopts as focus the Winkler¿s Model, through One-Dimensional Analytical Method that bases the development of the CEDEVE program (Evolutionary Calculation of Displacements and Efforts in Braced Trenches). This program assimilates the wall as a beam of unitary width, being the soil modeled as springs with linear perfectly elastic-plastic behavior including histeresis. Struts and anchorages, of elastic behavior, with or without initials forces, can be introduced in the structure. The actions on the structure occur by the soil pressures, water pressures and eventually overloads in the soil surface. The calculations are performed in agreement with the excavation phases, leaving the actions (soil pressures) and springs corresponding to the dug soil as well as introducing the struts/anchorages, so that the efforts and displacements happened in the previous phases are properly considered in the calculations of the following phases. The process of cover the trench with earth, when it exists, is also considered. A important differential of the CEDEVE program regarding other similar ones is the possibility of the inclusion of the temperature effects in the calculations of the displacements and efforts, and such thermal effects can be considered on the struts, what promotes the tendency of its stretch, that being impeded partially, generates consequent compression and also in the own retaining wall through gradients that induce bending and, therefore, also influencing on the loads on the struts system. A practical and numerical study is done with the intention of validate and verify the CEDEVE program, firstly testing their results with the program SAP 2000 and, after that, comparing the results generated with several other available programs (SPW2003, DEEP and ESTWIN). The effect of the temperature on the struts, calculated by CEDEVE, is compared with some results of available instrumentations in the consulted bibliography. Besides this, a comparative study with some Empirical and Semi-Empirical Methods was done. In general, it is possible to conclude that the Winkler¿s Model used in the modeling of the problem generates satisfactory results and its relationship cost benefit is quite attractive in the analysis of retaining structures / Doutorado / Estruturas / Mestre em Engenharia Civil

Design of retaining structures depends upon the load which is transferred from backfill soil as well as external loads and also the resisting capacity of the structure. The traditional safety factor approach of the design of retaining structures does not address the variability of soils and loads. The properties of backfill soil are inherently variable and influence the design decisions considerably. A rational procedure for the design of retaining structures needs to explicitly consider variability, as they may cause significant changes in the performance and stability assessment. Reliability based design enables identification and separation of different variabilities in loading and resistance and recommends reliability indices to ensure the margin of safety based on probability theory. Detailed studies in this area are limited and the work presented in the dissertation on the Optimum design of retaining structures under static and seismic conditions: A reliability based approach is an attempt in this direction. This thesis contains ten chapters including Chapter 1 which provides a general introduction regarding the contents of the thesis and Chapter 2 presents a detailed review of literature regarding static and seismic design of retaining structures and highlights the importance of consideration of variability in the optimum design and leads to scope of the investigation. Targeted stability is formulated as optimization problem in the framework of target reliability based design optimization (TRBDO) and presented in Chapter 3. In Chapter 4, TRBDO approach for cantilever sheet pile walls and anchored cantilever sheet pile walls penetrating sandy and clayey soils is developed. Design penetration depth and section modulus for the various anchor pulls are obtained considering the failure criteria (rotational, sliding, and flexural failure modes) as well as variability in the back fill soil properties, soil-steel pile interface friction angle, depth of the water table, total depth of embedment, yield strength of steel, section modulus of sheet pile and anchor pull. The stability of reinforced concrete gravity, cantilever and L-shaped retaining walls in static conditions is examined in the context of reliability based design optimization and results are presented in Chapter 5 considering failure modes viz. overturning, sliding, eccentricity, bearing, shear and moment failures in the base slab and stem of wall. Optimum wall proportions are proposed for different coefficients of variation of friction angle of the backfill soil and cohesion of the foundation soil corresponding to different values of component as well as lower bounds of system reliability indices. Chapter 6 presents an approach to obtain seismic passive resistance behind gravity walls using composite curved rupture surface considering limit equilibrium method of analysis with the pseudo-dynamic approach. The study is extended to obtain the rotational and sliding displacements of gravity retaining walls under passive condition when subjected to sinusoidal nature of earthquake loading. Chapter 7 focuses on the reliability based design of gravity retaining wall when subjected to passive condition during earthquakes. Reliability analysis is performed for two modes of failure namely rotation of the wall about its heel and sliding of the wall on its base are considering variabilities associated with characteristics of earthquake ground motions, geometric proportions of wall, backfill soil and foundation soil properties. The studies reported in Chapter 8 and Chapter 9 present a method to evaluate reliability for external as well as internal stability of reinforced soil structures (RSS) using reliability based design optimization in the framework of pseudo static and pseudo dynamic methods respectively. The optimum length of reinforcement needed to maintain the stability against four modes of failure (sliding, overturning, eccentricity and bearing) by taking into account the variabilities associated with the properties of reinforced backfill, retained backfill, foundation soil, tensile strength and length of the geosynthetic reinforcement by targeting various component and system reliability indices is computed. Finally, Chapter 10 contains the important conclusions, along with scope for further work in the area. It is hoped that the methodology and conclusions presented in this study will be beneficial to the geotechnical engineering community in particular and society as a whole.