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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Liaunų atraminių sienų analizė, taikant skirtingas projektines prielaidas / Structural analysis of flexible retaining wall using different design aproaches

Nenartavičienė, Lina 26 June 2008 (has links)
Baigiamajame magistro darbe analizuotos skirtingi liaunų atraminių sienų įrengimo variantai. Joms sumodeliuot ir paskaičiuot panaudota Prosheet ir GEO4 programos. Analizuojamos atraminės sienos, įrengtos smėliuose, kurių vidinės trinties kampas φ = 30 , sankabumas c = 0 kPa, ir moliuose, kurių vidinės trinties kampas φ = 26 , sankabumas c = 15 kPa. Skaičiavimų rezultatų lentelėse pateiktos įražų reikšmės ir skirtumai pavaizduoti grafiškai. Taip pat buvo išanalizuota, polių ilgiai, kuriuos suskaičiuoja kiekviena programa ir pavaizduota grafiškai. Išnagrinėjus, dėl ko gaunami skirtingi rezultatai, pateikiamos baigiamojo darbo išvados. Darbą sudaro 7 dalys: įvadas, 4 teorinės dalys, penktoji dalis - skaičiavimų rezultatai, išvados, literatūros sąrašas. Darbo apimtis – 63 p. teksto be priedų, 72 p. skaičiavimų rezultatų, 89 iliustr., 28 lent. Atskirai pridedami darbo priedai: 1 priedas 168 p. ir 2 priedas 168 p.. Priedai yra projektavimo programų atskirų variantų rezultatai, 3 priedas – paruoštas straipsnis vienuoliktai Lietuvos jaunųjų mokslininkų konferencijai bei pažyma apie straipsnio priėmimą spausdinimui. / In the master thesis it was analysed different method of retaining walls contruction. Prosheet and GEO4 programs werw used for calculation and design. Retaining walls were constructed in sandy soil or in clay. Properties of sand: angle of internal friction φ = 30 , cohesion c = 0 kPa. Properties of clayer soil: φ = 26 , c = 15 kPa. The stress values are given in the tables and differences showen graphically. Lengths of piles calculated are using each programme were analyzed and given graphically. After analysis of results, there were formulated an conclusion. Thesis consist of 7 chapters: introduction, 4 theoretical chapter, results of calculations, conclusions and references. Thesis consist of 63 text pages, 73 pages of calculations, including 89 illustrations and 28 tables. In addition 3 annexes are attached. Two of them are calculations and an article in the Young scientists conference.
82

Hidrotechnikos statinių gežbetoninių atraminių sienų ilgaamžiškumo įvertinimas / The Evaluation of Durability of Reinforced Concrete Retaining Walls of Hydraulic Structures

Čekanavičius, Tomas 03 June 2009 (has links)
Naudojamų hidrotechnikos statinių konstrukcijos veikiamos įvairių apkrovų ir neigiamo aplinkos poveikio nudėvimos, susiformuoja pažaidos. Pavojingiausios pažaidos, mažinančios pagrindinių laikančiųjų konstrukcijų (atraminių sienų) laikančiąją galią. Netekus laikomosios galios kyla grėsmė viso hidrotechnikos statinio patikimumui ir ilgaamžiškumui. Darbo tikslas – įvertinti hidromazgų atraminių sienų betono paviršinio sluoksnio ilgaamžiškumą apibrėžiančius rodiklius. Atlikus tyrimus nustatyta pagrindinė gelžbetoninių atraminių sienų charakteristika – betono gniuždomasis stipris. Pagal stiprio tyrimo rezultatus įvertintas Gailiušių hidromazgo atraminės sienos patikimumas ir nustatyta, kuris betono apsauginio sluoksnio ilgaamžiškumo rodiklis tiksliausiai atspindi atraminių sienų ilgaamžiškumo skaičiavimo rezultatus. Siūloma ilgaamžiškumo vertinimui naudoti 3.11 formulę. / Constructions of hydraulic structures are under the influence of different loads and negative environment impacts. Due to environmental impacts some deteriorations on the walls take place. The most dangerous kind of deteriorations reduces the bearing capacity of main constructions. The loss of the bearing capacity is very dangerous for the reliability and durability of the retaining wall. The purpose of this paper is to evaluate indicies defining the durability of the concrete covering layer of the retaining walls of hydroschemes. After the analysis it was found out the main characteristics of the reinforced concrete retaining walls – the compression strength of the concrete. The reliability of the retaining walls of Gailiušių hydroscheme was evaluated using the compression strength analysis. It was found out which indicator of the concrete covering layer durability gives the most correct counting results. It is suggested to use formula 3.11 for evaluation of durability.
83

NUMERICAL STUDY AND LOAD AND RESISTANCE FACTOR DESIGN (LRFD) CALIBRATION FOR REINFORCED SOIL RETAINING WALLS

HUANG, BING 29 January 2010 (has links)
Load and resistance factor design (LRFD) (often called limit states design (LSD)) has been mandated in the AASHTO Bridge Design Specifications and will be adopted in future editions of Canadian Highway Bridge Design Code for all transportation-related structures including reinforced soil retaining walls. The ultimate objective of this thesis work was to carry out reliability-based analysis for load and resistance factor design calibration for rupture and pullout limit states for steel and geosynthetic reinforced soil walls under self-weight and permanent surcharge loading conditions. In order to meet this objective it was necessary to generate large databases of measured load and resistance data from many sources and in some cases to propose new design models that improve the accuracy of underlying deterministic load and resistance models. Numerical models were also developed to model reinforced soil wall performance. These models were used to investigate load prediction accuracy of current analytical reinforcement load models. An important feature of the calibration method adopted in this study is the use of bias statistics to account for prediction accuracy of the underlying deterministic models for load and resistance calculations, random variability in input parameter values, spatial variation and quality of data. In this thesis, bias is defined as the ratio of measured to predicted value. The most important end product of the work described in this thesis is tabulated resistance factors for rupture and pullout limit states for the internal stability of steel and geosynthetic reinforced soil walls. These factors are developed for geosynthetic reinforced soil wall design using the current AASHTO Simplified Method, a new modified Simplified Method, and the recently proposed K-Stiffness Method. Useful quantitative comparisons are made between these three methods by introducing the concept of computed operational factors of safety. This allows designers to quantify the actual margin of safety using different design approaches. The thesis format is paper-based. Ten of the chapters are comprised of journal papers that have been published (2), are in press (2), in review (3) and the remaining (3) to be submitted once the earlier background papers are accepted. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2010-01-28 18:07:22.284
84

SEISMIC PERFORMANCE OF GEOSYNTHETIC-SOIL RETAINING WALL STRUCTURES

Zarnani, Saman 29 April 2011 (has links)
Vertical inclusions of expanded polystyrene (EPS) placed behind rigid retaining walls were investigated as geofoam seismic buffers to reduce earthquake-induced loads. A numerical model was developed using the program FLAC and the model validated against 1-g shaking table test results of EPS geofoam seismic buffer models. Two constitutive models for the component materials were examined: elastic-perfectly plastic with Mohr-Coulomb (M-C) failure criterion and non-linear hysteresis damping model with equivalent linear method (ELM) approach. It was judged that the M-C model was sufficiently accurate for practical purposes. The mechanical property of interest to attenuate dynamic loads using a seismic buffer was the buffer stiffness defined as K = E/t (E = buffer elastic modulus, t = buffer thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m3 was observed to be the practical range for the optimal design of these systems. Parametric numerical analyses were performed to generate design charts that can be used for the preliminary design of these systems. A new high capacity shaking table facility was constructed at RMC that can be used to study the seismic performance of earth structures. Reduced-scale models of geosynthetic reinforced soil (GRS) walls were built on this shaking table and then subjected to simulated earthquake loading conditions. In some shaking table tests, combined use of EPS geofoam and horizontal geosynthetic reinforcement layers was investigated. Numerical models were developed using program FLAC together with ELM and M-C constitutive models. Physical and numerical results were compared against predicted values using analysis methods found in the journal literature and in current North American design guidelines. The comparison shows that current Mononobe-Okabe (M-O) based analysis methods could not consistently satisfactorily predict measured reinforcement connection load distributions at all elevations under both static and dynamic loading conditions. The results from GRS model wall tests with combined EPS geofoam and geosynthetic reinforcement layers show that the inclusion of a EPS geofoam layer behind the GRS wall face can reduce earth loads acting on the wall facing to values well below those recorded for conventional GRS wall model configurations. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-28 16:56:57.084
85

Nutzung von Betriebsauslässen für die Hochwasserentlastung von Talsperren

Pohl, Reinhard, Martin, Helmut 10 March 2015 (has links) (PDF)
Während die güteorientierte Bewirtschaftung von Stauräumen in der Vergangenheit hauptsächlich bei der langfristigen Bewirtschaftung eine Rolle spielte, gewinnt sie in jüngerer Zeit immer mehr auch bei der kurzfristigen Abflusssteuerung als Vorentlastung und während der Hochwasserereignisse an Bedeutung. Dabei soll vor allem die Entlastung aus Horizonten mit geringerer Wasserqualität ermöglicht werden. Der vorliegende Beitrag beschäftigt sich mit den diesbezüglichen Möglichkeiten bei Nutzung vorhandener Entnahmeeinrichtungen und den Anforderungen an bauliche Ergänzungen. Es werden Grundsätze für die Planung, die Berechnung, den Betrieb und die Überwachung aus hydraulischer Sicht besprochen.
86

Dam break during the flood in Saxony/Germany in August 2002

Bornschein, Antje, Pohl, Reinhard 10 February 2015 (has links) (PDF)
The heavy rainfall event in August 2002 in Saxony/Germany caused the break of a flood retaining basin in a valley of the Erzgebirge Mountains. The rainfall event with ists hyrologic characteristics and dam break event were analysed and an outflow hydrograph was determing. The propagation of the dam break flood wave in the valleyas of the Briesnitz and Müglitz Rivers has been simulated. Calculated values were compared with some observed data.
87

Seismic response of retaining walls.

Hoque, Md. Zaydul. Carleton University. Dissertation. Engineering, Civil. January 1992 (has links)
Thesis (M. Eng.)--Carleton University, 1993. / Also available in electronic format on the Internet.
88

Avalia??o do desempenho de uma cortina de estacas espa?adas, atirantada, em areia / PERFORMANCE OF A SPACED PILES WALL, ANCHORED BY TIEBACKS, IN SAND

Santos, Fabiana Alves dos 16 December 2013 (has links)
Made available in DSpace on 2014-12-17T14:48:18Z (GMT). No. of bitstreams: 1 FabianaAS_DISSERT.pdf: 5525244 bytes, checksum: b567af14ad5856197ebf8368098dd7fb (MD5) Previous issue date: 2013-12-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / It is presented the analysis of a retaining wall designed for the basement of a residential building, located in Natal/RN, which consists in a spaced pile wall, anchored by tiebacks, in sand. This structure was instrumented in order to measure the wall s horizontal movements and the load distribution throughout the anchor fixed length. The horizontal movements were measured with an inclinometer, and the loads in the anchors were measured with strain gages, installed in three places throughout the anchor fixed length. Measurements for displacement were done right after the implementation of each stage of the building and right after the conclusion of the building, and the measurements for loads in the anchors were done during the performance test, at the moment of the locking off and, also, right after the conclusion of the building. From the data of displacement were obtained velocity and acceleration data of wall. It was found that the time elapsed on braced installation was decisive in the magnitude of the displacements. The maximum horizontal displacement of wall ranged between 0,18 and 0,66% of the final depth of excavation. The loads in the anchors strongly reduced to approximately half the anchor fixed length, followed an exponential distribution. Furthermore, it was found that there was a loss of load in the anchors over time, reaching 50% loss in one of them / O presente trabalho apresenta um estudo sobre uma estrutura de conten??o projetada para constru??o do subsolo de um edif?cio residencial multifamiliar, localizado na cidade de Natal/RN, que consiste em uma cortina de estacas escavadas ancorada por tirantes, em areia. Essa estrutura foi instrumentada a fim de se medirem os deslocamentos horizontais da cortina e a distribui??o de cargas ao longo do trecho ancorado dos tirantes. Os deslocamentos horizontais foram medidos atrav?s de inclin?metro, e as cargas nos tirantes foram obtidas com uso de extens?metros el?tricos de resist?ncia instalados em tr?s pontos ao longo do trecho ancorado. As medi??es de deslocamento foram feitas ap?s cada etapa de execu??o da cortina e ap?s a conclus?o da obra, enquanto as medi??es de carga nos tirantes foram feitas durante os ensaios de recebimento, no momento da incorpora??o e tamb?m ap?s a conclus?o da obra. A partir dos dados de deslocamento foram obtidos dados de velocidade e acelera??o da cortina. Constatou-se que o tempo gasto na instala??o do escoramento foi decisivo na magnitude dos deslocamentos. O deslocamento horizontal m?ximo final da cortina variou entre 0,18 e 0,66% da profundidade final de escava??o. As cargas nos tirantes sofrem uma redu??o muito acentuada at? aproximadamente a metade do trecho ancorado, seguindo uma distribui??o exponencial. Al?m disso, constatou-se que houve perda de carga nos tirantes ao longo do tempo, chegando a 50% de perda em um deles
89

Uso de inclinómetros para monitoreo de las deformaciones en un muro anclado para un proyecto en el conglomerado de Lima

Chávez Carmen, Fernando, Correa Izurieta, Luis Manuel January 2015 (has links)
El estudio consiste en un monitoreo de deformaciones con el uso de un inclinómetro instalado a trasdós de un muro de concreto armado con ocho niveles de anclajes en una excavación de 32 metros de profundidad en un proyecto de edificación en el distrito de San Isidro. Debido a que la metodología del muro anclado es muy utilizada en los últimos años en la ciudad de Lima, se considera necesario realizar un estudio del comportamiento de este tipo de estructura de retención, con el objetivo de conocer si la máxima deformación está dentro de los rangos permitidos por las normas internacionales, más aún en nuestro entorno, en donde no se tiene una normativa que regule este tipo de obras. La tesis se apoya en una revisión bibliográfica que ha permitido conocer estudios de deformaciones en estructuras de retención, analizar aspectos generales del comportamiento de los muros anclados, así como aspectos relacionados a la instrumentación geotécnica específicamente a los inclinómetros. La metodología adoptada seguirá un método cuantitativo, asimismo será de nivel descriptiva y también explicativa. Por otro lado, se considera que será de tipo aplicada siguiendo un diseño no experimental, además de ser prospectiva y transversal. Se ha logrado concluir que la deformación máxima del muro instrumentado está dentro de lo esperado, cumpliendo los rangos de las normas y de otras experiencias mencionadas en el marco teórico de esta tesis, además, tanto los resultados entregados por el inclinómetro como los presentados por el modelo en PLAXIS 2D, son similares, ya que muestra la tendencia hacia donde se dan las deformaciones. The study consists of a strain monitoring using an inclinometer installed to backfill of a retaining wall with eight anchors levels at a 32 meters deep excavation, in a building project in the district of San Isidro. The methodology of the retaining wall is widely used in recent years in the city of Lima, for that reason it is considered necessary to study the behavior of this type of retaining structure, in order to determine whether the maximum deformation is within the range allowed by international standards, even in our environment, where there is no legislation regulating this type of work. The thesis is based on a literature review, including studies of deformation of retaining structures, general aspects of the behavior of anchored walls and also issues related to geotechnical instrumentation specifically inclinometers. The methodology is based on a quantitative method, considering a descriptive level and an explanatory level as well. On the other hand, it is considered to be a rate applied contemplating a non-experimental design, as well as being prospective and transversal. The maximum deformation of the wall is within the expectations, satisfying the standards ranges and other experiences mentioned in the theoretical literature of this thesis and the results delivered by the inclinometer as the results presented by the PLAXIS 2D model are similar, because it shows the trend where the deformations are given.
90

Estruturas de contenção reforçadas com geossintéticos / Reinforced retaining structures with geosynthetics

Emerson Oliveira Pedroso 06 October 2000 (has links)
Este trabalho apresenta a construção e instrumentação de uma estrutura de contenção reforçada com geotêxtil, com 4,0 m de altura, construída na cidade de Nova Odessa-SP. A instrumentação consistiu em medir os deslocamentos horizontais e verticais com barras de aço e placas magnéticas, respectivamente. Além disso, foram realizadas simulações numéricas para comparar os resultados medidos e simulados do protótipo e avaliar o comportamento da estrutura para alguns tipos de solo, rigidez da inclusão e arranjos das inclusões. Pode-se concluir que os resultados medidos e simulados estão concordantes. Através das análises paramétricas concluiu-se que aumentando-se a rigidez do solo reduz-se os deslocamentos horizontais da estrutura. Com o aumento na rigidez da inclusão obtém-se menores deslocamentos, no entanto, em solos muito rígidos esta redução é pouco significativa. As estruturas com maior número de reforços reduzem as tensões em cada inclusão e diminuem os deslocamentos horizontais da estrutura. As forças de tração máximas, mobilizadas nas inclusões, são maiores para solos menos rígidos. Alguns resultados de obras instrumentadas, encontrados na literatura, são apresentados e comparados com os medidos e simulados. Destas comparações concluiu-se que o tipo de solo é o fator que mais influencia no desempenho de estruturas de contenção reforçadas com geossintéticos / This work presents the construction and instrumentation of a geotextile reinforced retaining structure, with 4,0 m height, built in the city of Nova Odessa-SP. The instrumentation consisted of measuring the horizontal and vertical displacements with steel bars and magnetic plates, respectively. Numeric simulations were accomplished to compare the measured and simulated results of the prototype and to evaluate the behavior of the structure for some soil types, reinforcement rigidity and different reinforcement layout. It was concluded that the measured and simulated results are in good agreement. The parametric analyses showed that the amount of horizontal displacements of the structure are reduced when the rigidity of the soil increases. Although smaller displacements are obtained when the rigidity of the inclusion is increased, in very rigid soils this reduction is not very significant. Structures with larger number of reinforcements reduce the stresses in each inclusion, decreasing the horizontal displacements of the structure. The maximum tensile forces mobilized in the inclusions, are larger for less rigid soils. Some case record results documented in the literature are presented and compared with the measured and simulated results obtained in this work. These comparisons allowed to conclude that the soil type is the most relevant factor in the performance of reinforced retaining structure with geosynthetics

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