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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.
61

Mapeamento geotécnico da bacia córrego da Barra, aplicação do penetrômetro de impacto em estudos de processos erosivos São Pedro - SP - escala 1:10.000 / Engineering geological mapping of the Barra stream basin using soil penetrometer in the study of erosive processes in São Pedro - SP - scale: 1:10.000

Crisley do Nascimento Guimarães 03 March 2008 (has links)
Este trabalho consiste em um mapeamento geotécnico da bacia do córrego da Barra, localizada no município São Pedro, no Estado de São Paulo, apresentando uma área aproximada de 56,5 \'KM POT.2\'. Para realização deste trabalho, efetuou-se um levantamento dos trabalhos anteriores realizados na área, fotointerpretação, e trabalhos de campo. Foram elaborados documentos cartográficos na escala 1:10.000: mapa de substrato rochoso, mapa de materiais inconsolidados, declividade e inventário das feições erosivas. Utilizou-se o penetrômetro de impacto (modelo IAA/Planalsucar-Stolf) para a determinação da resistência a penetração, entre as profundidades de 10 a 60 cm. Em seguida estes resultados foram correlacionados com a ocorrência de erosões na bacia, determinando assim qual o solo e qual o tipo de uso que favorecem a ocorrência e a evolução dos processos erosivos. / An engineering geological mapping was carried out in the basin of stream Barra, located in the São Pedro municipality in the state of São Paulo-Brasil. The area of 56,5 \'KM POT.2\' were mapped based on information of previous works, photointerpretation, and field works. The following cartographic documents were performed in 1:10.000 scale: rock substratum, unconsolidated materials, slope and inventory of erosive features. The penetrometer for soil (IAA/Planalsucar-Stolf) was utilized to determine the penetration resistance of the soil from 10 to 60 cm of depth. Soon afterwards the results of penetration resistance, soil type, use and occupation were correlated to establish the main factors in the erosion process.
62

Mapeamento geotécnico da bacia córrego da Barra, aplicação do penetrômetro de impacto em estudos de processos erosivos São Pedro - SP - escala 1:10.000 / Engineering geological mapping of the Barra stream basin using soil penetrometer in the study of erosive processes in São Pedro - SP - scale: 1:10.000

Guimarães, Crisley do Nascimento 03 March 2008 (has links)
Este trabalho consiste em um mapeamento geotécnico da bacia do córrego da Barra, localizada no município São Pedro, no Estado de São Paulo, apresentando uma área aproximada de 56,5 \'KM POT.2\'. Para realização deste trabalho, efetuou-se um levantamento dos trabalhos anteriores realizados na área, fotointerpretação, e trabalhos de campo. Foram elaborados documentos cartográficos na escala 1:10.000: mapa de substrato rochoso, mapa de materiais inconsolidados, declividade e inventário das feições erosivas. Utilizou-se o penetrômetro de impacto (modelo IAA/Planalsucar-Stolf) para a determinação da resistência a penetração, entre as profundidades de 10 a 60 cm. Em seguida estes resultados foram correlacionados com a ocorrência de erosões na bacia, determinando assim qual o solo e qual o tipo de uso que favorecem a ocorrência e a evolução dos processos erosivos. / An engineering geological mapping was carried out in the basin of stream Barra, located in the São Pedro municipality in the state of São Paulo-Brasil. The area of 56,5 \'KM POT.2\' were mapped based on information of previous works, photointerpretation, and field works. The following cartographic documents were performed in 1:10.000 scale: rock substratum, unconsolidated materials, slope and inventory of erosive features. The penetrometer for soil (IAA/Planalsucar-Stolf) was utilized to determine the penetration resistance of the soil from 10 to 60 cm of depth. Soon afterwards the results of penetration resistance, soil type, use and occupation were correlated to establish the main factors in the erosion process.
63

Reologie viskózních modifikovaných past na bázi portlandského cementu určených ke tváření extruzí / A rheology of high viscosity portland cement pastes applied on extrusion technology

Tihlařík, Petr Unknown Date (has links)
The aim of this doctoral thesis is to verify a possibilities of fibercement extrusion. A mixture for extrusion is typical for its high toughness and high fiber content, as the fiber content may be several times higher than when utilizing other production methods. The technology of a twin shaft kneader makes it possible to produce homogenous mixture for extrusion with low water/cement ratio. With use of auger moulder a mixture of high toughness is formed to final shape. The extreme shear and pressure stress is applied in the process. Therefore high requirements are posed on the equipment.
64

Simple Techniques for the Implementation of the Mechanics of Unsaturated Soils into Engineering Practice

Oh, Won Taek January 2012 (has links)
Over the past 50 years, several advancements have been made in the research area of the mechanics of unsaturated soils. These advancements can be categorized into two groups; (i) development (or improvement) of testing techniques (or apparatus) to determine the mechanical properties of unsaturated soils and (ii) development of (numerical, empirical or semi-empirical) models to estimate the variation of mechanical properties of unsaturated soils with respect to suction based on the experimental results. Implementation of the mechanics of unsaturated soils in conventional geotechnical engineering practice, however, has been rather limited. The key reasons for the limited practical applications may be attributed to the lack of simple and reliable methods for (i) measuring soil suction in the field quickly and reliably and (ii) estimating the variation of mechanical properties of unsaturated soils with respect to suction. The main objective of this thesis research is to develop simple and reliable techniques, models or approaches that can be used in geotechnical engineering practice to estimate sol suction and the mechanical properties of unsaturated soils. This research can be categorized into three parts. In the First Part, simple techniques are proposed to estimate the suction values of as-compacted unsaturated fine-grained soils using a pocket penetrometer and a conventional tensiometer. The suction values less than 300 kPa can be estimated using a strong relationship between the compressive strength measured using a pocket penetrometer and matric suction value. The high suction values in the range of 1,200 kPa to 60,000 kPa can be estimated using the unique relationship between the initial tangent of conventional tensiometer response versus time behavior and suction value. In the Second Part, approaches or semi-empirical models are proposed to estimate the variation of mechanical properties of unsaturated soils with respect to suction, which include: - Bearing capacity of unsaturated fine-grained soils - Variation of bearing capacity of unsaturated fine-grained soils with respect to matric suction - Variation of initial tangent elastic modulus of unsaturated soils below shallow foundations with respect to matric suction - Variation of maximum shear modulus with respect to matric suction for unsaturated non-plastic sandy soils (i.e. plasticity index, Ip = 0 %) In the Third Part, approaches (or methodologies) are suggested to simulate the vertically applied stress versus surface settlement behavior of shallow foundations in unsaturated coarse-grained soils assuming elastic-perfectly plastic behavior. These methodologies are extended to simulate the stress versus settlement behavior of both model footings and in-situ plates in unsaturated coarse-grained soils. The results show that there is a reasonably good comparison between the measured values (i.e. soil suction, bearing capacity, elastic and shear modulus) and those estimated using the techniques or models proposed in this thesis research. The models (or methodologies) proposed in this thesis research are promising and encouraging for modeling studies and practicing engineers to estimate the variation of mechanical behavior of unsaturated soils with respect to matric suction.
65

Instrumentação avançada para tomada de decisão na avaliação da resistência do solo à penetração de raízes / not available

Rabello, Ladislau Marcelino 27 November 2003 (has links)
Neste trabalho é apresentado um instrumento para auxílio à tomada de decisão em processos que envolvem avaliações da resistência do solo à penetração de raízes. Seu desenvolvimento fundamenta-se na concepção de uma nova ferramenta instrumental avançada, que viabiliza em tempo quase real informações para análise da variabilidade espacial da resistência do solo à penetração de raízes, tanto para área como para perfil, devido aos processos de compactação natural ou artificial do solo. Ensaios para a medida da resistência do solo à penetração de raízes podem ser realizados tanto em ambiente laboratorial como diretamente em campo agrícola. Para o desenvolvimento utilizou-se o enfoque da instrumentação inteligente, bem como uma microsonda (ângulo de cone de 30º, diâmetro de base de 1,6 mm e comprimento total de 30 mm) sensoriada por célula de carga. Resultados mostram que medidas de resistência do solo à penetração de raízes podem ser realizadas até um limite de (49,03 +/- 0,07) Kgf com resolução de 1,57 Kgf. Adicionalmente, a versatilidade do sistema é verificada para a coleta de dados e interpretação da resistência do solo à penetração de raízes, uma vez que podem ser apresentados na forma de tabelas, gráficos unidimensionais, mapas bidimensionais e mapas tridimensionais. Desta maneira, o sistema possibilita ao usuário uma rápida interpretação sobre o estado de agregação do solo em áreas de cultivo agrícolas. / This work is presented an instrument for decision-making in agricultural processes based on the measurements and mapping of soil resistance to the root penetration. Its development was based on a new and advance instrumentation tool, which enables in almost real-time to acquire the necessary information for spatial variability analysis of the resistance to root of plants penetration in soils, due to, either, natural or artificial compaction soil processes, i.e., not only for an area of soil but also to soil profile. The system allows soil resistance essays for both laboratory and agricultural field. Moreover, intelligent instrumentation concept was focused in the development, as well as a microprobe (30º for the spire angle, 1,6 mm for the base diameter, and 30 mm of total length), sensored by strain-gage transducers. Results have shown that measurements of soil resistance to root of plant penetration are allowed up to the limit of (49,03 +/- 0,07) Kgf, with 1,57 Kgf of resolution. Additionally, the suitability of the system is verified for soil resistance data collection and its interpretation to root plant penetration, since they can be presented in format of tables, one-dimensional graphics, two-dimensional maps and three-dimensional maps. Therefore, this system allows to the users a fast interpretation of soil aggregation state in agricultural areas.
66

Efeito de sistemas de preparo de solo e do uso de microrganismos eficazes nas propriedades físicas do solo, produtividade e qualidade de batata / Effects of soil preparation systems and Efficient Microorganisms (EM) on soil physical properties, and improvement of potato yield and quality

Mitsuiki, Cassio 15 December 2006 (has links)
As propriedades físicas do solo são preponderantes para a qualidade e produtividade da cultura da batata. Assim, o objetivo do presente trabalho foi avaliar algumas propriedades físicas do solo e a produtividade e qualidade dos tubérculos de batata. O experimento foi instalado em áreas de produção de batata na Chapada Diamantina (BA), de abril a agosto de 2005. O solo foi preparado pelo sistema convencional e pelo sistema alternativo MAFES, ambos associados ou não com a aplicação de Microrganismos Eficazes (EM). Foram avaliadas: a densidade do solo, a estabilidade de agregados, a resistência do solo à penetração, a taxa de infiltração de água e a retenção de água no solo. Também foi avaliada a alteração dessas propriedades do solo em relação à área antes do preparo, que estava sob pastagem de Brachiaria brizantha. A massa de torrões e touceiras colhidas juntamente com os tubérculos, bem como os danos mecânicos verificados durante a colheita mecanizada e a porcentagem de tubérculos com danos causados por larva alfinete, sarna e podridões foram quantificados. A produtividade nos diferentes tratamentos foi avaliada dentro da classificação comercial. Em relação ao pasto, os preparos convencional e MAFES alteraram a maioria das propriedades físicas avaliadas. Na área preparada pelo sistema MAFES foi observado, em relação ao preparo convencional, menor resistência à penetração em profundidades de 20 a 45 cm e entre os camalhões. A taxa de infiltração de água foi semelhante entre as áreas preparadas pelos dois sistemas, porém no sistema convencional a infiltração é mais superficial ocorrendo de forma lateral ao longo do perfil. No sistema MAFES a infiltração ocorreu verticalmente no perfil do solo. Menor porcentagem de tubérculos com danos mecânicos foi obtida na área preparada pelo sistema MAFES, devido, principalmente, a menor massa de torrões e touceiras colhidas juntamente com os tubérculos nessa área. A aplicação de EM teve pouca influência nas propriedades físicas do solo, mas propiciou condições que favoreceram o ataque de larva alfinete e sarna aos tubérculos. Apesar da utilização de EM ter reduzido a produção de tubérculos na área preparada pelo sistema MAFES, a produtividade e qualidade dos tubérculos nessa área foi superior a da área preparada pelo sistema convencional. / The physical soil properties have a relevant role on the yield and quality of potato crop. Thus, the purpose of the present research was to evaluate the effects on some soil physical properties on productivity and quality of potato tubers. The trial was set up in a commercial potato production field located in the Chapada Diamantina, BA, from April to August, 2000. Two distinct soil preparation systems (conventional and MAFES system), either associated or not with application of EM, have been trialed. The following soil properties were evaluated: bulk density, aggregate stability, soil penetration resistance, soil water retention and water infiltration rate. In addition, were evaluated the changes of such soil properties in comparison with the area cultivated with the grass Brachiaria brizantha, prior soil preparation. Other evaluations were performed such as the clod mass and clump of roots harvested together with potato tubers, the level of damage to the tubers caused by mechanical harvesting, and the amount of tubers affected by potato tuber moth, rots, and common scab. The yields of the different treatments were evaluated and tubers graded according to commercial patterns. Compared to the grass, both conventional and MAFES soil preparation systems have changed the physical soil properties studied. MAFES system outperformed the conventional preparation giving lesser resistance to penetration at 20 to 45 cm deep and between hills. The water infiltration rate was similar for both soil preparation systems; however for the conventional system the infiltration pattern is superficial occurring laterally in the soil profile. Regarding MAFES systems, the infiltration occurred vertically. The area prepared MAFES system also gave a fewer percentage of tubers exhibiting mechanical damage, due to smaller clod mass and clump of roots harvested together with potato tubers. EM application did not benefit physical soil properties, however influenced a higher attack of potato tuber moth and common scab. Although the yield decrease in the area prepared with MAFES system when the EM was applied, in this area the productivity and tuber quality outperformed the conventional system.
67

Efeito de sistemas de preparo de solo e do uso de microrganismos eficazes nas propriedades físicas do solo, produtividade e qualidade de batata / Effects of soil preparation systems and Efficient Microorganisms (EM) on soil physical properties, and improvement of potato yield and quality

Cassio Mitsuiki 15 December 2006 (has links)
As propriedades físicas do solo são preponderantes para a qualidade e produtividade da cultura da batata. Assim, o objetivo do presente trabalho foi avaliar algumas propriedades físicas do solo e a produtividade e qualidade dos tubérculos de batata. O experimento foi instalado em áreas de produção de batata na Chapada Diamantina (BA), de abril a agosto de 2005. O solo foi preparado pelo sistema convencional e pelo sistema alternativo MAFES, ambos associados ou não com a aplicação de Microrganismos Eficazes (EM). Foram avaliadas: a densidade do solo, a estabilidade de agregados, a resistência do solo à penetração, a taxa de infiltração de água e a retenção de água no solo. Também foi avaliada a alteração dessas propriedades do solo em relação à área antes do preparo, que estava sob pastagem de Brachiaria brizantha. A massa de torrões e touceiras colhidas juntamente com os tubérculos, bem como os danos mecânicos verificados durante a colheita mecanizada e a porcentagem de tubérculos com danos causados por larva alfinete, sarna e podridões foram quantificados. A produtividade nos diferentes tratamentos foi avaliada dentro da classificação comercial. Em relação ao pasto, os preparos convencional e MAFES alteraram a maioria das propriedades físicas avaliadas. Na área preparada pelo sistema MAFES foi observado, em relação ao preparo convencional, menor resistência à penetração em profundidades de 20 a 45 cm e entre os camalhões. A taxa de infiltração de água foi semelhante entre as áreas preparadas pelos dois sistemas, porém no sistema convencional a infiltração é mais superficial ocorrendo de forma lateral ao longo do perfil. No sistema MAFES a infiltração ocorreu verticalmente no perfil do solo. Menor porcentagem de tubérculos com danos mecânicos foi obtida na área preparada pelo sistema MAFES, devido, principalmente, a menor massa de torrões e touceiras colhidas juntamente com os tubérculos nessa área. A aplicação de EM teve pouca influência nas propriedades físicas do solo, mas propiciou condições que favoreceram o ataque de larva alfinete e sarna aos tubérculos. Apesar da utilização de EM ter reduzido a produção de tubérculos na área preparada pelo sistema MAFES, a produtividade e qualidade dos tubérculos nessa área foi superior a da área preparada pelo sistema convencional. / The physical soil properties have a relevant role on the yield and quality of potato crop. Thus, the purpose of the present research was to evaluate the effects on some soil physical properties on productivity and quality of potato tubers. The trial was set up in a commercial potato production field located in the Chapada Diamantina, BA, from April to August, 2000. Two distinct soil preparation systems (conventional and MAFES system), either associated or not with application of EM, have been trialed. The following soil properties were evaluated: bulk density, aggregate stability, soil penetration resistance, soil water retention and water infiltration rate. In addition, were evaluated the changes of such soil properties in comparison with the area cultivated with the grass Brachiaria brizantha, prior soil preparation. Other evaluations were performed such as the clod mass and clump of roots harvested together with potato tubers, the level of damage to the tubers caused by mechanical harvesting, and the amount of tubers affected by potato tuber moth, rots, and common scab. The yields of the different treatments were evaluated and tubers graded according to commercial patterns. Compared to the grass, both conventional and MAFES soil preparation systems have changed the physical soil properties studied. MAFES system outperformed the conventional preparation giving lesser resistance to penetration at 20 to 45 cm deep and between hills. The water infiltration rate was similar for both soil preparation systems; however for the conventional system the infiltration pattern is superficial occurring laterally in the soil profile. Regarding MAFES systems, the infiltration occurred vertically. The area prepared MAFES system also gave a fewer percentage of tubers exhibiting mechanical damage, due to smaller clod mass and clump of roots harvested together with potato tubers. EM application did not benefit physical soil properties, however influenced a higher attack of potato tuber moth and common scab. Although the yield decrease in the area prepared with MAFES system when the EM was applied, in this area the productivity and tuber quality outperformed the conventional system.
68

Early Age Assessment of Cement Treated Materials

Young, Tyler B. 21 March 2007 (has links)
In order to avoid the occurrence of early-age damage, cement-treated base (CTB) materials must be allowed to cure for a period of time before the pavement can be opened to traffic. The purpose of this research was to evaluate the utility of the soil stiffness gauge (SSG), heavy Clegg impact soil tester (CIST), portable falling-weight deflectometer (PFWD), dynamic cone penetrometer, and falling-weight deflectometer for assessing early-age strength gain of cement-stabilized materials. Experimentation was performed at four sites on a pavement reconstruction project along Interstate 84 near Morgan, Utah, and three sites along Highway 91 near Richmond, Utah; cement stabilization was used to construct CTB layers at both locations. Each site was stationed to facilitate repeated measurements at the same locations with different devices and at different curing times. Because of the considerable attention they have received in the pavement construction industry for routine quality control and quality assurance programs, the SSG, CIST, and PFWD were the primary focus of the research. Statistical techniques were utilized to evaluate the sensitivity to curing time, repeatability, and efficiency of these devices. In addition, the ruggedness and ease of use of each device were evaluated. The test results indicate that the CIST data were more sensitive to curing time than the SSG and PFWD data at the majority of the cement-treated sites during the first 72 hours after construction. Furthermore, the results indicate that the CIST is superior to the other instruments with respect to repeatability, efficiency, ruggedness, and ease of use. Because the CIST is less expensive than the SSG and PFWD, it is more likely to be purchased by pavement engineers and contractors involved with construction of CTBs. For these reasons, this research suggests that the CIST offers greater overall utility than the SSG or PFWD for monitoring early-age strength gain of CTB. Further research is needed to identify appropriate threshold CIST values at which CTB layers develop sufficient strength to resist permanent deformation or marring under different types of trafficking.
69

Numerical study of geotechnical penetration problems for offshore applications

Zhou, Hongjie January 2008 (has links)
The research carried out in this thesis has concentrated on the application of numerical solutions to geotechnical penetration problems in offshore engineering. Several important issues closely relevant to deep-water oil and gas developments were investigated, covering installation of suction caisson foundations, interpretation of fullflow penetrometers and shallow penetration of a cylindrical object (submarine pipeline or T-bar), all in clayey sediments such as are often encountered in deep-water sites. These problems are commonly characterised by large vertical movements of structural elements relative to the seabed. A large deformation finite element method was adopted and further developed to simulate these challenging problems, referred to as Remeshing and Interpolation Technique with Small Strain. In this approach, a sequence of small strain Lagrangian increments, remeshing and interpolation of stresses and material properties are repeated until the required displacement has been reached. This technique is able to model relative motion between the penetrating objects and the soil, which is critical for evaluating soil heave inside the caissons, the effect of penetration-induced remoulding on the resistance of full-flow penetrometers, and influence of soil surface heave on the embedment of pipelines. '...' Simple expressions were presented allowing the resistance factors for the T-bar and ball penetrometers to be expressed as a function of the rate and strain-softening parameters. By considering average strength conditions during penetration and extraction of these full-flow penetrometers, an approximate expression was derived that allowed estimation of the hypothetical resistance factor with no strain-softening, and hence an initial estimate of the stain-rate dependency of the soil. Further simulations of cyclic penetration tests showed that a cyclic range of three diameters of the penetrometers was sufficient to avoid overlap of the failure mechanism at the extremes and mid-point of the cyclic range. The ball had higher resistance factors compared with the T-bar, but with similar cyclic resistance degradation curves, which could be fitted accurately by simple expressions consistent with the strain-softening soil model adopted. Based on the curve fitting, more accurate equations were proposed to deduce the resistance factor with no strain-softening, compared with that suggested previously based on the resistances measured in the first cycle of penetration and extraction. The strain-rate dependency was similar in intact or post-cyclic soil for a given rate parameter. The resistance factor for the post-cyclic condition was higher than that for the initial conditions, to some degree depending upon soil sensitivity and brittleness parameter. For the shallow penetration of a cylindrical object, the penetration resistance profile observed from centrifuge model tests was very well captured by the numerical simulation. The mechanism of shear band shedding was reproduced by the numerical technique, although the frequency of the shear band generation and the exact shape of the heave profile were not correctly captured, which were limited by the simple strainsoftening soil model adopted.
70

Resistance analysis of axially loaded drilled shafts socketed in shale

Burkett, Terry Bryce 05 November 2013 (has links)
An investigation into the load-settlement behavior of two drilled shafts, founded in shale, is presented. The motivation for this research is to advance the understanding on how drilled shafts react under loading in stiff clays and shales. The objectives of the study are to measure the strengths within the subsurface material at the test site, estimate the unit side shear and unit end bearing of the shale-shaft interaction by running two axial load tests, and compare the results to the current design methods that are used to predict the axial capacity of drilled shafts. A comprehensive field investigation, performed by Fugro Consultants, provided strength profiles of the subsurface material at the test site. Through the cooperation of the Texas Department of Transportation (TxDOT), the Association of Drilled Shaft Contractors, and McKinney Drilling Company, two drilled shafts were installed at a highway construction site in Austin, Texas. The load tests were performed by Loadtest, Inc.; using the patented Osterberg-Cell™ loading technique to axially displace the shafts. Ensoft, Inc. installed strain gauges at multiple levels within the shafts, making it possible to analyze the shaft mobilization during loading. Ultimate end bearing values of about 100- and 120-ksf were measured for Test Shafts #1 and #2, respectively. The current methods for estimating unit end bearing, developed by TxDOT and the Federal Highway Administration, provide fairly accurate predictions when compared to the measured information. The ultimate side resistance obtained near the O-Cell™ in each test was about 20-ksf, however, the measured ultimate side resistance steadily decreased nearing the tip of the shaft. For the zones where the side resistance was believed to be fully mobilized, the TxDOT design method accurately predicts the side resistance. A limited amount of information is currently available for load tests performed in soils with TCP values harder than 2-in per 100 blows. Additional load test information should allow for a stronger correlation between TCP tests and unit resistances for very hard clay-shales, as well as, allowing for further evaluation of the shale-shaft interaction near the shaft tip. The results presented herein demonstrate the effectiveness of the current design methods for drilled shafts and the non-uniformity of side resistance within one- to two-diameters of the shaft tip. / text

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