No / It is important to consider the potential instability of the seabed due to the accumulation of wave-induced pore pressure in the design of a composite breakwater as the pore pressure within the seabed can considerably build-up under waves loading and eventually leads to a sharp decrease of the effective stress. Due to the importance in practical engineering, many theoretical models have been developed to evaluate the magnitude and distribution of the residual pore pressure. However, most of these studies treat the soil skeleton as an invariant medium, which ignores the damping of the soil strength due to the reduction of the effective stress. In this study, a two-dimensional poro-elastoplastic model, in which the influence of the reduction of the effective stress on the soil strength has been considered, is proposed to investigate the accumulation of pore water pressure around a composite breakwater and its effect on the soil characteristics. The simulation results show that the liquefaction is likely to occur around the toe of the breakwater due to the accumulation of pore water pressure there. The liquefaction leads to the decrease of soil resistance, which has great effect on the development of the residual pore pressure. Analysis shows that the development of residual pore pressure is also greatly affected by both the wave height and soil permeability. The simulation demonstrates that if the decrease of soil resistance is not considered, the soil liquefaction depth will be overestimated. / National Natural Science Foundation of China (Grant No. 51479053), the 111 Project (Grant No. B12032), the marine renewable energy research project of State Oceanic Administration (GHME2015GC01), the Natural Science Foundation of Jiangsu province (Grant No. BK20150804), Colleges and Universities in Jiangsu Province Plans for Graduate Research and Innovation Projects (Grant No. B1504708) and the Distinguished Visiting Fellowship from the Royal Academy of Engineering

Virtual Reality (VR) simulators have become popular because of two distinctive merits. One is the capability to transfer data and information to users in an intuitive way by means of 3-D high-quality graphics output and real input devices. The other is the capability to represent physical systems in mathematical models so that meaningful responses of the systems can be predicted. Previous efforts in VR excavating machine simulator development, however, showed a lack of balance between the fidelity of the model of the physics and the visual representation of the simulated equipment. In order to ensure that a VR construction excavator simulator provides convincing operating results to users, the focus of simulator development needs to be shifted to interaction of physically valid soil and the excavator machine. This research aims to contribute to the development of a VR construction excavator simulator system by proposing a mathematical model of excavator digging and a calculation methodology. The mathematical model of excavator digging provides physically meaningful soil-bucket interaction information to a simulator. The calculation methodology provides systematic and efficient computation methods to ensure the seamless integration of the excavator digging model with a VR simulator system as well as adequate system speed. As a result, the simulator is realized as an engineering process tool equipped with real-time interactivity. / Ph. D.

The trenchless technology known as pipe ramming for construction of culverts and buried pipes under roadways or other infrastructure has gained significant popularity due to its cost-effectiveness and ability to alleviate surface disruptions associated with open-cut trenching. Although the experience with pipe ramming is increasing, there has been remarkably little technical guidance available for engineers to appropriately specify aspects of a pipeline or culvert installation, including the planning of feasible layouts, rates of penetration, pipe diameters, and hammers. This research provides a comprehensive engineering framework for evaluation of culvert installations at the planning phase to address the gaps in knowledge associated with pipe ramming. Presently there are no existing and proven techniques for prediction of settlement, vibration, driving stresses, soil resistance to ramming, and drivability for pipe ramming installations. This study has adopted existing drivability, soil resistance, settlement, and vibration prediction models from pipe jacking, microtunneling, and pile driving models and examined their applicability in pipe ramming installations, resulting in new and technology-specific design guidance. The development of this comprehensive engineering guidance is based on engineering calculations empirically tuned using a database of actual performance measurements. Field observations of five production installations and a full-scale experiment were conducted to form the performance database employed to understand the mechanics associated with pipe ramming installations, ranging from vertical ground movements, ground vibrations, and installation performance. Settlement prediction was evaluated using the inverted normal probability distribution based models, and these methods over-estimated the observed settlements close to the center of the pipes and under-estimated settlements at radial distances away from the pipe. A pipe-ramming-specific hyperbolic model was developed for better prediction of the vertical settlement induced by pipe ramming in granular soils. Attenuation of observed pipe ramming-induced vibrations was modeled using a simple semi-empirical approach, and the calibrated model resulted in reasonable predictions of the ground vibrations for granular soils. The static soil resistance to ramming was evaluated using the traditional quasi-static pipe jacking models and the models resulted in inaccurate predictions for instrumented pipe ramming installations. Therefore pipe ramming-specific static soil resistance models were developed for both the face and casing resistance in granular soils. Principles of stress wave theory routinely applied in the drivability analyses for pile foundations were adopted for the evaluation of the dynamic response pipes during ramming. Reliable estimates of the static soil resistance and dynamic soil parameters were obtained through signal matching processes. Data-informed drivability analysis were performed to simulate the magnitude of driving stresses and develop drivability curves which relate the penetration resistance of a given pipe and hammer to the range of static soil resistances. The study culminates in the first comprehensive framework and recommendations for the installation of pipes by ramming, and should help owners, consultants, and contractors to appropriately plan pipe ramming installations. / Graduation date: 2013

Made available in DSpace on 2014-06-11T19:33:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-21Bitstream added on 2014-06-13T19:04:48Z : No. of bitstreams: 1 almeida_cx_dr_jabo.pdf: 641425 bytes, checksum: 8ee6de028f930932e687bf840fa7cec8 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O estudo de indicadores de qualidade dos solos é fundamental para avaliar o nível de degradação imposta pelo uso agrícola e para estabelecer estratégias de manejo sustentáveis. O objetivo geral deste trabalho foi avaliar a qualidade de um Latossolo Vermelho distrófico típico sob cultivo convencional (CC) e sistema de semeadura direta (PD), por meio de indicadores físicos e da avaliação da produção das culturas da soja e do milho. Os objetivos específicos foram: i) comparar a eficiência de funções de pedotransferência para a curva de resistência do solo à penetração presentes na literatura, por meio do ajuste de dados obtidos com o penetrômetro de impacto e também com o penetrômetro eletrônico; ii) determinar a resistência do solo à penetração (RP) durante o ciclo das culturas relacionando-a ao conteúdo de água no solo (Ug); e, iii) determinar alguns indicadores de qualidade física do solo, relacionando-os com as características agronômicas das culturas. Os sistemas de uso e manejo do solo foram: CC e PD por sete e oito anos consecutivos (solo de textura média) e CC e PD por nove e dez anos consecutivos (solo de textura argilosa). Foram determinadas a RP, a porosidade total, a macroporosidade, a microporosidade, a retenção de água no solo, o índice S, a densidade, a densidade do solo máxima e também a densidade do solo relativa. Nas culturas da soja e do milho foram avaliadas: massa seca das raízes, altura das plantas, altura de inserção da primeira vagem/espiga, número de vagens por planta de soja, massa seca da parte aérea do milho e produtividade. As Equações ; ; e não diferiram e foram as mais precisas e acuradas na predição da RP. Dentre os sistemas de manejo, embora o CC tenha apresentado melhores resultados em relação aos indicadores de qualidade física do solo, o PD foi o que proporcionou maior produção de milho / The study of indicators of soil quality is essential to assess the level of degradation imposed by agricultural use and to establish sustainable management strategies. The aim of this study was to evaluate the quality of an Oxisol under conventional (CC) and no-tillage (NT), through soil physical indicators and assessing the soybeans and corn crops yield. The specific objectives were: i) compare the efficiency of pedotransfer functions due to soil resistance to penetration curve in the literature, by adjusting the data obtained with the impact penetrometer and also with the electronic penetrometer), ii) monitoring the soil resistance to penetration (PR) during the crop cycle relating it to the soil water content (Wc), and iii) determine some soil physical indicators, relating them to the agronomic characteristics of crops. The management systems were: CC and NT to seven and eight years consecutives (sandy loam soil) and CC and NT to nine and ten years consecutives (clayey soil). The PR, total porosity, macroporosity and microporosity, soil water retention, index S, soil bulk density, maximum dry bulk density, and also the relative bulk density were determined. The agronomic characteristics of soybean and corn crops have been evaluated: roots dry mass, height plant, insertion of the first spike height/pod, pods per soybean plant number, corn shoot dry mass and yield. The equations ; ; e did not differ and were the most precise and accurate in prediction of soil resistance to penetration. Among the management systems, although the CC has shown better results in relation to soil physical indicators, the NT was that the highest corn yield

Made available in DSpace on 2014-06-11T19:28:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-06Bitstream added on 2014-06-13T18:48:29Z : No. of bitstreams: 1 andre_ja_me_jabo.pdf: 439702 bytes, checksum: 6ebd97c9b9dd43dde1a634877f8ec886 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O preparo de solo é a etapa mais importante na instalação de um canavial, pois proporciona melhores condições para o desenvolvimento da cultura. Assim, o objetivo deste trabalho foi avaliar os efeitos de quatro sistemas de preparo de solo, utilizados na cultura do amendoim, sobre o desenvolvimento da cultura da cana-de-açúcar em sucessão, e sobre a qualidade física de um Latossolo Vermelho Distrófico. Os sistemas de preparo foram: plantio direto (PD), cultivo mínimo (CM), cultivo mínimo + gradagem (CM+G) e preparo convencional (PC). As subparcelas consistiram na presença ou ausência de palhada de cana-de-açúcar antes do preparo. A presença ou ausência de palhada não interferiu na produtividade, nem nos atributos físicos do solo em estudo. A maior produtividade de cana-de-açúcar foi obtida no PC (101,6 TCH). O CM teve os melhores resultados com relação aos atributos físicos do solo, porém teve a menor produtividade (61,4 TCH) / The tillage system is the most important stage in the sugarcane crop, because provide bests conditions to the crop development. In this way, the objective of this work, was evaluate the effects of four tillage systems , used in a peanut crop, in a sugarcane crop development in sucession, and in an Oxisol. The tillage systems were: No tillage (PD), minimum tillage (CM), minimum tillage + leveling disc (CM+G) and conventional tillage (PC). The subplots made up of presence or absence of sugarcane straw before the tillage. The presence or absence of sugarcane straw not interfered in productivity e in the soil physical attributes in study. The bigger productivity was got in the conventional tillage (101,6 HTC). The CM had the best results in the soil physical attributes, but had a smaller productivity (61.4 HTC)

Orientador: José Frederico Centurion / Banca: Elias Nascentes Borges / Banca: Ednaldo Carvalho Guimarães / Banca: Teresa Cristina Tarle Pissarra / Banca: Renato de Mello Prado / Resumo: O estudo de indicadores de qualidade dos solos é fundamental para avaliar o nível de degradação imposta pelo uso agrícola e para estabelecer estratégias de manejo sustentáveis. O objetivo geral deste trabalho foi avaliar a qualidade de um Latossolo Vermelho distrófico típico sob cultivo convencional (CC) e sistema de semeadura direta (PD), por meio de indicadores físicos e da avaliação da produção das culturas da soja e do milho. Os objetivos específicos foram: i) comparar a eficiência de funções de pedotransferência para a curva de resistência do solo à penetração presentes na literatura, por meio do ajuste de dados obtidos com o penetrômetro de impacto e também com o penetrômetro eletrônico; ii) determinar a resistência do solo à penetração (RP) durante o ciclo das culturas relacionando-a ao conteúdo de água no solo (Ug); e, iii) determinar alguns indicadores de qualidade física do solo, relacionando-os com as características agronômicas das culturas. Os sistemas de uso e manejo do solo foram: CC e PD por sete e oito anos consecutivos (solo de textura média) e CC e PD por nove e dez anos consecutivos (solo de textura argilosa). Foram determinadas a RP, a porosidade total, a macroporosidade, a microporosidade, a retenção de água no solo, o índice S, a densidade, a densidade do solo máxima e também a densidade do solo relativa. Nas culturas da soja e do milho foram avaliadas: massa seca das raízes, altura das plantas, altura de inserção da primeira vagem/espiga, número de vagens por planta de soja, massa seca da parte aérea do milho e produtividade. As Equações ; ; e não diferiram e foram as mais precisas e acuradas na predição da RP. Dentre os sistemas de manejo, embora o CC tenha apresentado melhores resultados em relação aos indicadores de qualidade física do solo, o PD foi o que proporcionou maior produção de milho / Abstract: The study of indicators of soil quality is essential to assess the level of degradation imposed by agricultural use and to establish sustainable management strategies. The aim of this study was to evaluate the quality of an Oxisol under conventional (CC) and no-tillage (NT), through soil physical indicators and assessing the soybeans and corn crops yield. The specific objectives were: i) compare the efficiency of pedotransfer functions due to soil resistance to penetration curve in the literature, by adjusting the data obtained with the impact penetrometer and also with the electronic penetrometer), ii) monitoring the soil resistance to penetration (PR) during the crop cycle relating it to the soil water content (Wc), and iii) determine some soil physical indicators, relating them to the agronomic characteristics of crops. The management systems were: CC and NT to seven and eight years consecutives (sandy loam soil) and CC and NT to nine and ten years consecutives (clayey soil). The PR, total porosity, macroporosity and microporosity, soil water retention, index S, soil bulk density, maximum dry bulk density, and also the relative bulk density were determined. The agronomic characteristics of soybean and corn crops have been evaluated: roots dry mass, height plant, insertion of the first spike height/pod, pods per soybean plant number, corn shoot dry mass and yield. The equations ; ; e did not differ and were the most precise and accurate in prediction of soil resistance to penetration. Among the management systems, although the CC has shown better results in relation to soil physical indicators, the NT was that the highest corn yield / Doutor

Orientador: José Frederico Centurion / Banca: Itamar Andrioli / Banca: José Ricardo Mantovani / Resumo: O preparo de solo é a etapa mais importante na instalação de um canavial, pois proporciona melhores condições para o desenvolvimento da cultura. Assim, o objetivo deste trabalho foi avaliar os efeitos de quatro sistemas de preparo de solo, utilizados na cultura do amendoim, sobre o desenvolvimento da cultura da cana-de-açúcar em sucessão, e sobre a qualidade física de um Latossolo Vermelho Distrófico. Os sistemas de preparo foram: plantio direto (PD), cultivo mínimo (CM), cultivo mínimo + gradagem (CM+G) e preparo convencional (PC). As subparcelas consistiram na presença ou ausência de palhada de cana-de-açúcar antes do preparo. A presença ou ausência de palhada não interferiu na produtividade, nem nos atributos físicos do solo em estudo. A maior produtividade de cana-de-açúcar foi obtida no PC (101,6 TCH). O CM teve os melhores resultados com relação aos atributos físicos do solo, porém teve a menor produtividade (61,4 TCH) / Abstract: The tillage system is the most important stage in the sugarcane crop, because provide bests conditions to the crop development. In this way, the objective of this work, was evaluate the effects of four tillage systems , used in a peanut crop, in a sugarcane crop development in sucession, and in an Oxisol. The tillage systems were: No tillage (PD), minimum tillage (CM), minimum tillage + leveling disc (CM+G) and conventional tillage (PC). The subplots made up of presence or absence of sugarcane straw before the tillage. The presence or absence of sugarcane straw not interfered in productivity e in the soil physical attributes in study. The bigger productivity was got in the conventional tillage (101,6 HTC). The CM had the best results in the soil physical attributes, but had a smaller productivity (61.4 HTC) / Mestre

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A prÃtica da agricultura tradicional pode degradar a qualidade dos recursos naturais e por isso se tornar insustentÃvel, o que leva a necessidade de uma abordagem ecolÃgica, possibilita a escolha de manejos agrÃcolas que associem a produÃÃo de alimentos e a conservaÃÃo dos recursos naturais, como acontece nos sistemas agroflorestais. A simplificaÃÃo do agroecossistema reduz a diversidade, afetando a biota e a qualidade do solo. Assim, objetivou-se: i) avaliar indicadores da qualidade e Ãndices da qualidade, resistÃncia e resiliÃncia do solo, ii) avaliar a diversidade da pedofauna dos agroecossistemas e iii) identificar as relaÃÃes entre a flora nos perÃodos seco e chuvoso com a riqueza da pedofauna. Foram estudados os sistemas agroflorestais do tipo agrossilvipastoril, silvipastoril e o tradicional, atualmente em uso e apÃs diferentes perÃodos de pousio; alÃm de um sistema menos impactado (MATA). A qualidade do solo (QS) foi avaliada por indicadores quÃmicos e fÃsicos de solo e calculados os Ãndices de qualidade, resistÃncia e resiliÃncia. A pedofauna foi coletada, nos perÃodos seco e chuvoso, usando armadilhas de queda, identificando-se os grupos taxonÃmicos e posterior determinaÃÃo da riqueza, densidade, diversidade e uniformidade. As Ãreas sob sistemas agroflorestais mantiveram a QS, o pousio recuperou e o tradicional a reduziu, sendo menos resiliente e resistente. No perÃodo seco, os sistemas agroflorestais apresentaram baixas diversidade e uniformidade, porÃm riquezas semelhante à MATA, enquanto que as Ãreas em pousio apresentaram altas diversidade e uniformidade. Houve semelhanÃas de diversidade e uniformidade entre as Ãreas sob cultivo tradicional e MATA. No perÃodo chuvoso, os sistemas agroflorestais apresentaram densidade e riqueza semelhantes à MATA. As Ãreas tradicionais em pousio apresentaram densidade, riqueza, diversidade e uniformidade semelhantes à MATA. Conclui-se que os sistemas agroflorestais sÃo sustentÃveis, seis e nove anos de pousio sÃo suficientes para retomar a condiÃÃo do sistema menos impactado e manejo tradicional reduz a qualidade, resistÃncia e resiliÃncia do solo. Os sistemas agroflorestais apresentam diversidade e uniformidade da pedofauna semelhantes ao ambiente menos impactado quando hà disponibilidade hÃdrica. A riqueza das espÃcies arbÃreas e a sazonalidade climÃtica determinam a riqueza da pedofauna. / Traditional agriculture can degrade natural resources becoming unsustainable. Hence, ecological approaches on agriculture enable the choice of agricultural management,which associates food production and the maintenance of natural resources, as agroforestry systems. The simplified agroecosystem reduces diversity, causing deleterious effects on soil biota and on soil quality,. Thus, the aim of this work was: i) to assess quality indicators and soil quality, resistance and resilience indexes, ii) to evaluate the diversity of edaphic fauna of agroecosystems and iii) to identify flora and dry and rainy seasons to edaphic fauna abundance. Agrosilvopastoral, silvopastoral, and traditional agroecosystems were studied, under use and under different periods of fallow, besides the natural vegetation (MATA). Soil quality (QS) was analyzed according to some indicators and from them quality, resistance and resilience indexes were calculated. Edaphic fauna was collected under dry and rainy seasons, using PITFALL TRAPS. The fauna was identified under taxonomic groups and the indexes: abundance, density, diversity, and uniformity here determined. The relation between fauna and flora and the seasons was analyzed using general linear models. Agroforestries maintained QS, traditional system under fallow recovered it, and the traditional system reduced it and it was less resilient and resistant. In the dry season, agroforestries showed low diversity and uniformity, therefore presenting similar abundance to MATA, while areas under fallow showed high diversity and uniformity. There were similarities in diversity and uniformity between traditional system and MATA. In the rainy season, agroforestries showed density and abundance similar to MATA,. Traditional systems under fallow showed density, abundance, diversity, and uniformity similar to MATA. It is possible to conclude that agroforestry systems are sustainable. Six and nine years of fallow are enough to recover the condition of natural vegetation. Traditional management reduces quality, resistance and resilience of soil. Agroforestries show diversity and uniformity of pedofauna similar to the natural vegetation when water is available. The abundance of trees and weather seasonality determine the abundance of pedofauna.

Although it has been established that in-situ soil mixing has improved the bearing capacity of soils, additional research is needed to better understand the effect of soil mixing on lateral resistance of pile caps. To do this, in-situ soil mixing was used to strengthen weak clay adjacent to a pile cap of a driven pile foundation. The mass stabilization method or mass mixing was used to treat an 11 ft wide, 4 ft thick, and 10 ft deep zone consisting of an average 475 psf clay that was adjacent to a 9-pile group in 3x3 pile configuration capped with a 9 ft x 9 ft x 2.5 ft, 5000 psi concrete cap. The mass mixing involved 220 cubic ft of in-situ soil and was mixed with an additional 220 cubic ft of jet grout spoils producing a mixing ratio of 1 to 1. All of the mass mixing took place after construction of the pile caps. Laboratory testing of the mass mix slurry showed an unconfined compressive strength of 20,160 psf or 140 psi. Lateral load testing of the pile foundation was then undertaken. The results of this testing were compared with similar testing performed on the same foundation with native soil conditions. The lateral resistance of the native soil was 282 kips at a pile cap displacement of 1.5 inches, and the total lateral resistance of the pile foundation treated with mass mixing was increased by 62% or 170 kips. Of the 170 kips, 90% to 100% can be attributed to the increased passive force on the face of the mass mixed zone and shear on the sides and bottom denoting that the mass mixed zone behaved as a rigid block.

No description available.