Static and dynamic interaction mechanism of the retained soil-compressible geofoam buffer and yielding retaining structures requires further investigation. The present study, initiated on this motive, discusses the results of 1-g physical model tests and numerical analyses of cantilever retaining walls with and without deformable geofoam buffers between the wall and cohesionless granular backfill. 0.7m high walls with various wall thicknesses were utilized in the physical modeling. Dynamic tests were carried out by using a laminar container placed on a uni-axial shaking table. Influence of buffer thickness, geofoam type and wall flexibility as well as base excitation characteristics on the lateral earth pressures and flexural wall deflections were under concern. Outcomes of the analyses performed with FLAC-2D (v6.0) finite difference code were validated against the results of the physical model tests. It was observed that the arching effect induced in the retained soil by the lateral compression of the lower half of the geofoam buffer has a positive effect, as this zone is able to absorb a portion of the total unbalanced lateral force exerted by the backfill thus causing a reduction in the static and seismic lateral wall pressures. Relative thickness and stiffness of the geofoam buffer appear to be the most dominant factors affecting the reduction in earth thrust. Lateral earth pressure coefficients determined from physical model tests were compared with those calculated using methods available in the literature. Good agreement was observed between the predictions. Graphs were provided to estimate the static and dynamic lateral earth pressure coefficients for various combinations of wall stiffness and buffer characteristics. Analysis of a 6m high prototype cantilever wall subjected to an excitation recorded in August 17, 1999 Kocaeli earthquake by finite difference method exhibited the contribution of geofoam buffers on seismic performance of cantilever earth retaining walls. It was observed that the presence of an EPS geofoam inclusion provides a reduction of the permanent flexural wall deflections as well as total seismic thrust likely to be experienced by the wall during an earthquake.

Η ΒΥΠ διαθέτει αντίτυπο της διατριβής σε έντυπη μορφή στο βιβλιοστάσιο διδακτορικών διατριβών που βρίσκεται στο ισόγειο του κτιρίου της. / Εκτελώντας δυναμικές αναλύσεις με χρήση πεπερασμένων στοιχείων, αναλύεται η σεισμική απόκριση τεσσάρων τοίχων αντιστήριξης οπλισμένου εδάφους στην Ταϊβάν με στοιχεία πρόσοψης κυβόλιθους. Οι τοίχοι, των οποίων τα ύψη κυμαίνονται από 3.20 m έως 5.60 m και έχουν ως οπλισμούς στρώσεις γεωπλέγματος, υποβλήθηκαν στο σεισμό Chi-Chi (1999) και η συμπεριφορά τους κρίθηκε από επιτυχής έως ανεπιτυχής: δύο από αυτούς κατέρρευσαν, ένας υπέστη μόνο ελαφρές βλάβες, ενώ ο τέταρτος τοίχος παρέμεινε πρακτικά ανέπαφος. Η μη-γραμμική ανάλυση βασίσθηκε στα γνωστά γεωμετρικά και μηχανικά χαρακτηριστικά του κάθε τοίχου, του γεωπλέγματος, των γεωτεχνικών συνθηκών σε κάθε θέση, του είδους και των ιδιοτήτων του υλικού επίχωσης. Η συμπεριφορά του εδαφικού υλικού προσομοιώθηκε κάνοντας χρήση του κριτηρίου Mohr-Coulomb, ενώ ως διέγερση βάσης στις δυναμικές αναλύσεις πεπερασμένων στοιχείων χρησιμοποιήθηκαν τα καταγεγραμμένα επιταχυνσιογραφήματα κοντά στις θέσεις των τοίχων. Τα αποτελέσματα των αναλύσεων (και ειδικά η εκτιμώμενη παραμορφωμένη μορφή των τοίχων) επαλήθευσαν την παρατηρούμενη συμπεριφορά των τοίχων. Βασιζόμενοι στα αποτελέσματα, βρέθηκαν οι λόγοι της ανεπιτυχούς συμπεριφοράς των δύο τοίχων που κατέρρευσαν, ενώ εξηγήθηκε η διαφοροποίηση της συμπεριφοράς των δύο τοίχων που δεν υπέστησαν βλάβες. Επιπροσθέτως, πραγματοποιήθηκαν παραμετρικές αναλύσεις για να ευρεθεί η επίδραση σημαντικών παραμέτρων σχεδιασμού, όπως το βάθος θεμελίωσης του τοίχου, η απόσταση και το μήκος των οπλισμών, η συνεισφορά των ράβδων σύνδεσης στην ευστάθεια των στοιχείων πρόσοψης και η συνεισφορά της ανώτατης στρώσης οπλισμού στην ευστάθεια του τοίχου. Επίσης αναλύθηκε η ευστάθεια των τοίχων χρησιμοποιώντας ένα εμπορικά διαθέσιμο λογισμικό οριακής ισορροπίας, το οποίο βρέθηκε ικανό να προβλέψει την παρατηρούμενη επιτυχή και ανεπιτυχή συμπεριφορά των τεσσάρων τοίχων. / The seismic response of four reinforced soil segmental retaining walls in Taiwan, is analyzed using the dynamic finite element method. The walls – whose heights ranging from 3.20 m to 5.60 m and layers of geogrid reinforcement – were subjected to the Chi-Chi earthquake (1999) and their performance ranged from successful to unsuccessful: two of them were collapsed, one suffered only minor damage whereas the fourth wall remained practically intact. The non-linear analyses were based on the known geometrical and mechanical characteristics of each wall and of the geogrid reinforcement, the geotechnical conditions at each site and the type and properties of backfill material. The soil material behavior was modeled by using the Mohr-Coulomb failure criterion whereas recorded accelerograms in the vicinity of the sites of the walls were used as base excitation in the dynamic finite analyses. The results of the analyses (and especially the estimated deformed shape of the walls) showed a remarkable agreement with the observed performance of the walls. Based on these results the reasons for the unsuccessful performance of the two failed walls were identified whereas the differentiation of the behavior of the two undamaged walls was explained. Furthermore, parametric analyses were conducted to identify the effects of such important design parameters as the depth of the foundation of the wall, the spacing and length of reinforcement, the contribution of connecting pins to the stability of the facing elements as well as the contribution of the top layer of reinforcement to the stability of the wall. The stability of the walls were also analyzed by using a commercially available limit equilibrium software which was found to be able to predict the observed successful and unsuccessful performance of the four walls.

Made available in DSpace on 2014-12-17T14:48:12Z (GMT). No. of bitstreams: 1 JohnGBG_DISSERT.pdf: 5632038 bytes, checksum: eabbd6743af14f648742650469c3d48f (MD5) Previous issue date: 2012-07-02 / A numerical study on the behavior of tied-back retaining walls in sand, using the finite element method (FEM) is presented. The analyses were performed using the software Plaxis 2D, and were focused on the development of horizontal displacements, horizontal stresses, shear forces and bending moments in the structure during the construction process. Emphasis was placed on the evaluation of wall embedment, tie-back horizontal spacing, wall thickness, and free anchor length on wall behavior. A representative soil profile of a specific region at the City of Natal, Brazil, was used in the numerical analyses. New facilities built on this region often include retaining structures of the same type studied herein. Soil behavior was modeled using the Mohr-Coulomb constitutive model, whereas the structural elements were modeled using the linear elastic model. Shear strength parameters of the soil layers were obtained from direct shear test results conducted with samples collected at the studied site. Deformation parameters were obtained from empirical correlations from SPT test results carried out on the studied site. The results of the numerical analyses revealed that the effect of wall embedment on the investigated parameters is virtually negligible. Conversely, the tie-back horizontal spacing plays an important role on the investigated parameters. The results also demonstrated that the wall thickness significantly affects the wall horizontal displacements, and the shear forces and bending moments within the retaining structure. However, wall thickness was not found to influence horizontal stresses in the structure / O presente trabalho apresenta um estudo num?rico atrav?s do m?todo dos elementos finitos (MEF) utilizando-se o aplicativo computacional Plaxis 2D, com o objetivo de verificar aspectos do comportamento de estruturas de conten??o atirantadas em areia. As an?lises foram dirigidas ao desenvolvimento dos deslocamentos horizontais, das tens?es horizontais e dos esfor?os internos (esfor?o cortante e momento fletor) durante o processo construtivo da estrutura. As simula??es num?ricas inclu?ram avalia??es da influ?ncia do comprimento da ficha, do espa?amento horizontal entre os tirantes, da espessura da parede e do comprimento do trecho livre. O perfil de solo utilizado nas simula??es num?ricas ? representativo de uma determinada regi?o da Cidade de Natal RN, na qual s?o constru?das com frequ?ncia conten??es do tipo analisado no presente trabalho. Utilizou-se o modelo constitutivo de Mohr-Coulomb para simular o comportamento do solo e o modelo el?stico linear para simular o comportamento dos elementos estruturais. Os par?metros de resist?ncia do solo foram determinados por meio de ensaios de cisalhamento direto e os par?metros de deformabilidade foram estimados atrav?s de correla??es emp?ricas obtidas de resultados de ensaios SPT executados na regi?o em estudo. Os resultados obtidos mostraram que varia??es no comprimento da ficha praticamente n?o influenciam o comportamento da estrutura, no ?mbito dos par?metros avaliados, ao passo que o espa?amento horizontal entre os tirantes apresenta forte influ?ncia sobre essas grandezas. Verificou-se tamb?m que a espessura da parede apresenta consider?vel influ?ncia sobre os deslocamentos horizontais e sobre os esfor?os internos e pouca influ?ncia sobre as tens?es horizontais

Made available in DSpace on 2014-12-17T14:48:17Z (GMT). No. of bitstreams: 1 GilvanBSJ_DISSERT.pdf: 3763149 bytes, checksum: 74cfc52e8eaadf3e1722a2a37d52aca9 (MD5) Previous issue date: 2014-03-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Usually masonry structures has low tension strength, hence the design to flexural efforts can results in high reinforcement ratio, specification of high unit and prism strength, structural members with larger section dimensions and modification in structural arrangement to be possible to use masonry members. The main objective of this study is to evaluate the stiffness, the efforts distribution and the effect of horizontal elements (girders) and vertical elements (counterforts) distribution on the behavior of masonry blocks retaining walls. For this purpose, numerical modeling was performed on typical retaining wall arrangements by varying the amount and placement of horizontal and vertical elements, beyond includes elements simulating the reactions of the soil supporting the foundation of the wall. The numerical modeling also include the macro modeling strategy in which the units, mortar and grout are discretized by a standard volume that represents the masonry elastic behavior. Also, numerical model results were compared with those ones of simplified models usually adopted in bending design of masonry elements. The results show horizontal displacements, principal and shear stresses distribution, and bending moments diagrams. From the analysis it was concluded that quantity and manner of distribution of the girders are both important factors to the panel flexural behavior, the inclusion of the foundation changed significantly the behavior of the wall, especially the horizontal displacements, and has been proposed a new way of considering the flanges section of the counterforts / As estruturas de alvenaria solicitadas por elevados esfor?os de flex?o podem necessitar, dada a baixa resist?ncia ? tra??o, de elevadas taxas de armadura; de maior resist?ncia ? compress?o da alvenaria; de elementos estruturais com maiores dimens?es ou mesmo um rearranjo desses elementos para possibilitar o emprego da alvenaria. O estudo ora apresentado tem por objetivo avaliar a rigidez, a distribui??o de esfor?os e o efeito da distribui??o de cintas e de elementos verticais (contrafortes) no caso de muros de arrimo de alvenaria estrutural de blocos. Para tanto, foram realizadas modelagens num?ricas de arranjos t?picos de muro, variando a quantidade e o posicionamento de cintas horizontais, o espa?amento entre os contrafortes, al?m de incluir elementos simulando as rea??es do solo de apoio na funda??o do muro. A modelagem num?rica realizada empregou a estrat?gia de macromodelagem em que os blocos, a argamassa e o graute s?o discretizados pelo volume padr?o representativo do comportamento el?stico da alvenaria. Alternativamente, os resultados do modelo num?rico foram comparados com os de modelos simplificados comumente adotados nos projetos desse tipo de elemento estrutural. A an?lise dos resultados consistiu na verifica??o dos deslocamentos transversais, na distribui??o das tens?es principais (para balizar um futuro modelo de bielas e tirantes e os modos de ruptura), na distribui??o das tens?es de cisalhamento, e na obten??o de diagramas de momento fletor. A partir das an?lises foi poss?vel concluir que n?o apenas a quantidade, mas tamb?m a forma de distribui??o das cintas ? um fator relevante para a distribui??o dos esfor?os no painel fletido (pano de alvenaria), a inclus?o dos elementos de funda??o alterou significativamente o comportamento do muro, principalmente os deslocamentos transversais, al?m de ter sido proposta uma nova forma de considera??o de flanges na se??o resistente do contraforte

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Cordia trichotoma species (louro-pardo) is widely distributed in tropical and subtropical forests at South America. Its wood has high economic value and it is considered one of the priority tree species for planting destined to reestablishment altered area and for commercial purposes. However, researches related to morphological, physiological and biochemistry performance are incipient, mainly associated to the use of water-retaining polymers as well as the fertilization for suitable growing in the field. In this sense, the present study was shared in two chapters: Chapter I aimed to verify the behavior of C. trichotoma seedling submitted over four phosphor applications (0, 120, 240 e 360 Kg of P2O5 ha-1), with presence and absence of water-retaining polymers (5 g L-1 per seedling-1). In the Chapter II was studied the influence of different types of fertilizers (cattle manure, poultry manure and mineral fertilizer) in the C. trichotoma, with and without the presence of water-retaining polymers. The planting was conducted on a Sandy Typic Hapludalf, at Central region of Rio Grande do Sul State, Brazil. For seedlings evaluation, was measured morphological (height and stem diameter, leaf area and dry matter of shoot and root), physiological (chlorophyll a fluorescence), biochemistry parameters (photosynthetic pigments and phosphatase acid enzyme activity) and nutrients content in the leaf. In general, it was evident the occurrence of high rainfall index after planting phase and, there was no influence of the use of water-retaining polymers in the survival and seedlings growth. In the Chapter I, was noticed that C. trichotoma species require soil fertility, demanding phosphatase fertilization. It is recommended the use of near 220 Kg P2O5 ha-1 for seedling achieve high growth in the shoot, stem diameter and dry matter of shoot and root. This fertilizer content is recommended for more exploitation of luminous energy and less loss of fluorescence energy. In the Chapter II, was showed for this species that fertilization with cattle manure can be considered alternative option, replacing mineral fertilization originated from scare sources and with high purchase cost. The use of 10 liters of cattle manure per seedling provide suitable growth and photosynthetic activity. In the present study, we noticed that the evaluation of emission fluoresce of chlorophyll a and phosphatase acid enzyme activity can be used to identified alteration in plants metabolism caused by low nutrients availability as well as to control the demand of seedling fertilization of this species. / A espécie Cordia trichotoma (louro-pardo) é amplamente distribuída em florestas tropicais e subtropicais na América do Sul, possuindo madeira de alto valor econômico agregado, sendo considerada uma das arbóreas prioritárias para plantios destinados ao restabelecimento de áreas alteradas e fins comerciais. No entanto, pesquisas relacionadas ao seu desempenho morfológico, fisiológico e bioquímico são incipientes, principalmente no que diz respeito a influência do uso de polímeros hidroretentores, assim como à fertilização para o adequado crescimento em plantios. Nesse sentido, o presente estudo foi dividido em dois capítulos, sendo que no Capítulo I objetivou-se verificar o comportamento das plantas de C. trichotoma submetidas a aplicação de quatro doses de fósforo (0, 120, 240 e 360 kg de P2O5 ha-1), na presença e ausência de polímero hidroretentor (5 g L-1 por muda-1). No Capítulo II foi determinada a influência de diferentes tipos de adubações (dejeto bovino, dejeto de aves e fertilizante mineral) em mudas C. trichotoma, na presença e ausência de polímeros hidroretentores. Os plantios foram conduzidos em Argissolo Vermelho distrófico arênico, na região Central do Rio Grande do Sul, Brasil. Na avaliação das mudas, foram determinados os atributos morfológicos (altura e diâmetro do coleto, área foliar, matéria seca aérea e radicular), fisiológicos (fluorescência da clorofila a), bioquímicos (pigmentos fotossintéticos, atividade da enzima fosfatase ácida e teor de nutrientes nas folhas). De forma geral, evidenciou-se que com a ocorrência de elevados índices pluviométricos na fase pós plantio, o uso de polímeros hidroretentores não influenciou a sobrevivência e o crescimento das mudas. No Capítulo I, percebeu-se que a espécie C. trichotoma é exigente em relação a fertilidade do solo, sendo responsiva à adubação fosfatada. Recomenda-se a utilização de cerca de 220 kg de P2O5 ha-1 para as mudas obterem maior crescimento em altura, diâmetro do coleto e produção de matéria seca aérea e radicular. Essa dose também é indicada para maior aproveitamento da energia luminosa e menor índice de perda de energia por fluorescência. No Capítulo II, evidenciou-se que para essa espécie a adubação com dejeto bovino pode ser considerada uma alternativa em substituição à fertilização mineral, oriundos de fontes escassas e de maior custo de aquisição. O uso de 10 litros de dejeto bovino curtido por muda proporciona adequado crescimento e atividade fotossintética. Com o presente estudo percebeu-se que a avaliação da emissão de fluorescência da clorofila a e da atividade da enzima fosfatase ácida pode ser utilizada para identificar alterações no metabolismo das plantas, causadas pela baixa disponibilidade de nutrientes e monitorar a necessidade de adubação nas mudas dessa espécie

Flera forskare skriver om vikten av att vara en attraktiv arbetsgivare, som idag är viktigare än någonsin, speciellt när konkurrensen om personal ökar. Genom att skapa ett attraktivt arbetsgivarvarumärke ökar chanserna att attrahera och behålla kompetent personal (Ehrenborg & Höglund, 2016). Tidigare forskning visar att flera olika faktorer är viktiga att ta hänsyn till i arbetet mot att skapa ett starkt arbetsgivarvarumärke, faktorer som bland annat motivation och intern marknadsföring (Grönroos, 1996; Lievens, 2007). I följande studie undersöks Högskolan Dalarnas attraktivitet som arbetsgivare utifrån ett medarbetarperspektiv, med syfte att finna attraktiva erbjudanden för att behålla och attrahera medarbetare. Studien är en metodkombination som i huvudsak bygger på en kvalitativ metod med kvantitativa inslag och har genomförts i form av intervjuer och en enkätundersökning med adjunkter på Högskolan Dalarna. I studien framkommer attraktiva attribut som flexibel arbetstid, möjlighet till utveckling och trygga relationer samt mindre attraktiva attribut som lön och förtroligt ledarskap. Vidare i studien diskuteras utvald teori och framtagen empiri som slutligen mynnar ut i ett antal förslag till hur Högskolan Dalarna kan fortsätta sitt arbete med arbetsgivarvarumärket i bemärkelsen att vara en attraktiv arbetsgivare. / Several researchers write about the importance of being an attractive employer, which today is more important than ever, especially when the competition for staff increases. By creating an attractive employer brand, the chances of attracting and retaining competent staff increase (Ehrenborg & Höglund, 2016). Previous research shows that several factors are important to consider in the work towards creating a strong employer brand, factors such as motivation and internal marketing (Grönroos, 1996; Lievens, 2007). In the following study, the University of Dalarna's attractiveness as an employer is examined from an employee perspective, with the aim of finding attractive offers for retaining and attracting employees. The study is a method combination based mainly on a qualitative method with quantitative elements and has been conducted in the form of interviews and a questionnaire survey with adjuncts at Dalarna University. The study reveals attractive attributes such as flexible working hours, opportunity for development and safe relationships, as well as less attractive attributes such as payroll and trustworthy leadership. In addition, the study discusses selected theory and empirical evidence that ultimately emerges in several proposals for how the Dalarna University can continue their work with the employer brand in the sense of being an attractive employer.

[pt] O projeto de estruturas de contenção de solos submetidas a carregamentos dinâmicos é um importante tema da engenharia geotécnica, principalmente nos países andinos. A abordagem mais comum consiste no emprego de métodos de equilíbrio limite (pseudo-estáticos) ou de técnicas baseadas na formulação de Newmark (1965) para cálculo de deslocamentos permanentes da estrutura. Um método pseudo-estático clássico é o apresentado por Mononobe-Okabe (1929) como uma extensão da teoria de Coulomb (1773), enquanto que Richards e Elms (1979) sugeriram um método de projeto baseado em deslocamentos permanentes. Nesta dissertação os resultados da aplicação do método dos elementos finitos na análise dinâmica do comportamento de um muro de gravidade são comparados com aqueles previstos por diversos outros métodos analíticos propostos na literatura, tanto em termos do cálculo de empuxos quanto de deslocamentos permanentes. As vantagens e limitações destes métodos são discutidas, bem como são discutidos vários aspectos da modelagem numérica que devem ser cuidadosamente considerados pelo engenheiro geotécnico para obter uma simulação representativa do problema dinâmico. / [en] The design of earth retaining structures during earthquakes is an important subject of the geotechnical engineering, mainly in the Andesian countries of South America. The most common approach consists in the use of some quasi-static method or technique based on Newmark s (1965) model to estimate inelastic displacements of the structure. The classical quasi-static method is the one proposed by Mononobe -Okabe (1926, 1929), as an extension of the Coulomb s (1773) theory to a dynamic context, while Richards and Elms (1979) suggested a design method based on inelastic displacements. In this thesis the dynamic response of a gravity retaining wall obtained through the finite element method are compared with those predicted by several other analytical formulation proposed in the literature, concerning both the resultant of the earth pressures and the wall displacements experienced during the earthquake. The advantages and shortcomings in the application of all these methods are discussed herein, as well as several modeling aspects are discussed that must be carefully considered by the geotechnical engineer in order to obtain a representative simulation of the dynamical problem.

Master of Science / Department of Civil Engineering / Stacey Kulesza / In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 (“Standard Method of Test for Determining Minimum Laboratory Soil Resistivity”). AASHTO T 288-12 is designed to test a soil sample’s electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate. In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material’s bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.

Orientador: Pérsio Leister de Almeida Barros / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-16T16:58:48Z (GMT). No. of bitstreams: 1 SantosJunior_PetrucioJosedos_M.pdf: 1818015 bytes, checksum: 92ab0f753dc226315fad2785fd0cd0bc (MD5) Previous issue date: 2010 / Resumo: A determinação do empuxo ativo através de métodos de equilíbrio limite, para análise de muros de contenção é prática comum na engenharia geotécnica, principalmente pela simplicidade analítica de sua obtenção. Porém, havendo a presença de uma superfície freática no solo arrimado tal determinação não apresenta resultado analítico, sendo então requerido um estudo numérico para obter um valor que auxilie com certa precisão nessa análise. Poucos trabalhos foram feitos sobre esse tema e ainda assim sua importância não deixa de ser relevante para a verificação das condições de estabilidade de estruturas de arrimo drenantes. Nesse trabalho é feita uma abordagem numérica através do Método dos Elementos de Contorno (MEC) para determinação da posição da superfície freática e posterior cálculo do empuxo ativo pelo Método de Coulomb considerando a influência dessa superfície. É implementado um programa de computador, cujo algoritmo de cálculo, baseado em MEC, apresenta a posição da freática, o valor da vazão total que chega ao sistema de drenagem e o empuxo ativo atuante sobre a estrutura de contenção / Abstract: The determination of active thrust in retaining wall analysis through limit equilibrium is a routine in geotechnical engineering, mostly due to analytic simplicity. However, when there is a phreatic surface in the retained soil, such determination does not present an analytic result. Then a numerical study is necessary to obtain a representative value of prore water pressures in the soil for the analysis. There are few technical publications about this theme, but its importance is recognized in drained retaining wall stability calculation. This work proposes a numerical approach using Boundary Element Method (BEM) to evaluate the position of phreatic surface and calculation of active thrust coefficient through Coulomb's method considering the influence of this position. A computer program, which calculation algorithm based on BEM is developed. It presents the results of the phreatic surface position, the total flow volume that arrives to the drainage system and the active thrust value / Mestrado / Geotecnia / Mestre em Engenharia Civil

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