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The soil-structure interaction models associated with laterally loaded deep foundations have typically been based on load tests involving relatively small diameter foundations. The lateral soil resistance for larger diameter foundations has been assumed to increase linearly with diameter; however, few, if any load tests have been performed to confirm this relationship. To better understand the lateral resistance of large diameter deep foundations in sand, a series of full scale, cyclic, lateral load tests were performed on two 1.2 m diameter drilled shafts and a 0.324 m diameter steel pipe pile in sand. Although the tests involve two different foundation types, the upper 2.4 m of the profile, which provides the majority of the lateral resistance, consists of sand compacted around both foundation types. Therefore, these test results make it possible to evaluate the effect of foundation diameter on lateral soil resistance. The drilled shafts were first loaded in one direction by reacting against a fifteen-pile group. Subsequently a load test was performed in the opposite direction by reacting against a 9-pile group. The soil profile below the 2.4 m-thick layer of compacted sand consisted of interbedded layers of sand and fine-grained soil. For the drilled shaft load tests, pile head deflection and applied load were measured by string potentiometers and load cells, respectively. Tilt was also measured as a function of depth with an inclinometer which was then used to calculate deflection and bending moment as a function of depth. For the pipe pile, deflection and applied load were also measured; however, bending moment was computed based on strain gauges readings along the length of the pile. The lateral response of the drilled shafts and pipe pile were modeled using the computer programs LPILE (Reese et al., 2000), SWM6.0 (Ashour et al., 2002), and FB-MultiPier Version 4.06 (Hoit et al., 2000). Comparisons were made between the measured and computed load-deflection curves as well as bending moment versus depth curves. Soil parameters in the computer programs were iteratively adjusted until a good match between measured and computed response of the 0.324 m pipe pile was obtained. This refined soil profile was then used to model the drilled shaft response. User-defined p-multipliers were selected to match the measured results with the calculated results. On average very good agreement was obtained between measured and computed response without resorting to p-multipliers greater than 1.0. These results suggest that a linear increase in lateral resistance with foundation diameter is appropriate. LPILE typically produced the best agreement with measured response although the other programs usually gave reasonable results as well. Cyclic loading generally reduced the lateral resistance of the drilled shafts and pile foundation by about 20%.

Deep foundations like auger-cast piles and drilled shafts frequently extend through liquefiable sand layers and bear on non-liquefiable layers at depth. When liquefaction occurs, the skin friction on the shaft decreases to zero, and then increases again as the pore water pressure dissipates and the layer begins to settle, or compact. As the effective stress increases and the liquefiable layer settles, along with the overlaying layers, negative skin from the soil acts on the shaft. To investigate the loss of skin friction and the development of negative skin friction, soil-induced load was measured in three instrumented, full-scale auger-cast piles after blast-induced liquefaction at a site near Christchurch, New Zealand. The test piles were installed to depths of 8.5 m, 12 m, and 14 m to investigate the influence of pile depth on response to liquefaction. The 8.5 m pile terminated within the liquefied layer while the 12 m and 14 m piles penetrated the liquefied sand and were supported on denser sands. Following the first blast, where no load was applied to the piles, liquefaction developed throughout a 9-m thick layer. As the liquefied sand reconsolidated, the sand settled about 30 mm (0.3% volumetric strain) while pile settlements were limited to a range of 14 to 21 mm (0.54 to 0.84 in). Because the ground settled relative to the piles, negative skin friction developed with a magnitude equal to about 50% of the positive skin friction measured in a static pile load test. Following the second blast, where significant load was applied to the piles, liquefaction developed throughout a 6-m thick layer. During reconsolidation, the liquefied sand settled a maximum of 80 mm (1.1% volumetric strain) while pile settlements ranged from 71 to 104 mm (2.8 to 4.1 in). The reduced side friction in the liquefied sand led to full mobilization of side friction and end-bearing resistance for all test piles below the liquefied layer and significant pile settlement. Because the piles generally settled relative to the surrounding ground, positive skin friction developed as the liquefied sand reconsolidated. Once again, skin friction during reconsolidation of the liquefied sand was equal to about 50% of the positive skin friction obtained from a static load test before liquefaction.

With the extension of the Nchwaning Mine shaft complex in the Northern Cape Province, various geological and geotechnical complications needed to be identified in order to ensure correct use of tunnelling methods and support techniques. An understanding of the geological history of the area and the resulting geotechnical nature was important in defining the rock mass quality ahead of shaft development. A total of 12 geotechnical boreholes were drilled, and an additional 18 old boreholes revisited to accurately detennine the stratigraphy, geological structure and associated weathering effects. Various soils and rock testing helped quantify the materials encountered. Sands of the Gordonia Fonnation form the surface cover of this area, and together with the weathered calcrete, calc-arenite, conglomerate and clay, they form part of the Cenozoic Kalahari Group. The 30m thick basal unit of red clay is common throughout this region. This silty clay material is problematic in that it is expansive and hygroscopic. The clay unit rests unconformably on folded, faulted and highly weathered shale of the Proterozoic Lucknow and Mapedi Formations of the Olifantshoek Supergroup. Unconformably below this sequence lies the manganiferous ore deposits of the Hotazel Member, which is contained within the Voelwater Formation of the Griqualand West Supergroup. For the development of the decline shaft through the Gordonia Formation a box cut was excavated to a depth of 25m. The anticipated poor geotechnical conditions for a further 125m below the Gordonia sands called for high quality permanent tunnel support in the upper weathered horizons. Barton's Q-analysis was adopted as a recognized tunnelling quality index to predict and quantify the rock mass characteristics ahead of the shaft. The highly variable and generally low Q-values from borehole core analysis indicated that precast tunnel lining be used for 800m (at 11.5°) through the entire weathered Cenozoic sequence and into the weathered shales immediately below the Red Clay. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

Construction of heavily loaded shallow foundations adjacent to deep foundation is generally avoided in common geotechnical engineering practice to minimize additional loads on deep foundations. However, with the growing trend of urbanization leading to a demand of new construction, it is not always possible to avoid such situation where a heavily loaded shallow foundation will be right next to the infrastructure resting on deep foundations. When this situation cannot be avoided, influence of soil pressures and deformations in soil, created by shallow foundation on adjacent deep foundation, must be evaluated. The study of interaction between deep foundations has been carried out by several researchers in terms of pile-soil-pile interaction. Similarly, there are many published studies on interaction between closely spaced shallow foundations in terms of bearing capacity and settlement. However, not much published literature is available for practicing engineers to analyze and design deep and shallow foundations when they are constructed adjacent to each other. Construction of heavily loaded mat adjacent to drilled shafts would cause complex interaction between the foundations. However, lateral stress and drag forces on the shafts resulting from the heavy load on the mat foundation are the two major factors that would affect the design and performance of shafts. Since there is not much literature and guidance available to analyze and design such kind of situation, a preliminary investigation was first carried out where magnitude of the drag forces and lateral forces on drilled shafts were estimated using simple geotechnical engineering principles. The limitations of preliminary analysis led to the need of more sophisticated analysis using finite element techniques. As a part of this research, a detailed parametric study using finite element techniques has been performed to better understand stress and deformation distributions, and develop simplified methods to analyze this type of problems. A stress bulb for lateral stresses under a uniformly loaded square foundation, similar to the pressure bulb for vertical stresses which is widely used in the geotechnical engineering practice, has been proposed, which provides a significant tool for practicing engineers to understand lateral stress distribution below a uniformly loaded square area and estimate lateral stresses on nearby deep foundations. Similarly, a deformation bulb under a uniformly loaded square foundation is proposed. A new term “Isodefers” has been proposed to refer the lines of equal deformation. Isodefers are also a significant tool for practicing engineers to understand vertical deformation distribution below a uniformly loaded square area and estimate drag forces on nearby deep foundations. A case study emerging from similar real life scenario has also been analyzed and results are discussed with suitable recommendations.

No description available.

No description available.

Möjligheter att förbättra Hofpartner ABs beräkningsmall för rullaxlar har undersökts. Undersökningen har fokuserat på användarvänlighet, ekonomi samt hållfasthet. Målet var att göra mallen mer lättanvänd. Nuvarande mall undersöks med resultat att den är väldigt svår att följa samt att dess värden inte överensstämmer särskilt bra med verkligheten i de flesta avseenden. Arbetet koncentreras därmed på att identifiera de existerande problemen och att åtgärda dem. Mallens funktioner utvärderas och beslut fattas om att reducera mallen till att endast hantera information som regelbundet används av företaget. Genom att minska mängden data ses möjligheter att göra mallen enklare att följa och mer lättanvänd med mindre krav på förkunskaper. Nya formler för hållfasthetsberäkningar framställs och implementeras i en nyskapad mall. Formlerna kontrolleras med analyser i FEM. Analyserna visar att de nya beräkningarna ger resultat närmare verkligheten. Kostnadsberäkningarna har konstruerats som en grund till Hofpartner att bygga vidare på. Formler är implementerade men en undersökning av företagets produktion krävs för att uppnå korrekta resultat. Undersökningen behöver utföras för att kartlägga tidsåtgång för företagets produktion, arbetet har endast lett till uppskattningar. Om undersökningen utförs har Hofpartner möjlighet att åstadkomma mycket rimliga resultat i mallen. / In this project the possibilities to improve Hofpartner AB's calculation model for reel shafts has been investigated. The investigation has focused on user friendliness, economy and strength calculations. The goal was to make the model easier to use. An investigation of the current model shows that it is difficult to follow the calculations and that the results in most cases are not particularly accurate. Thus the work is focused on identifying the existing problems and improving on them. Several of the functions in the model are removed and the model now only handles information that are used with some regularity. By reducing the amount of data covered by the model possibilities is seen to simplify usage and to reduce the amount of necessary prior knowledge. New formulas for the strength calculations are presented and implemented in a new model. The formulas are verified by analysis with FEM. The analysis shows that the model is providing results close to the real values. The economical calculations are constructed as a basis for Hofpartner to continue developing. The necessary formulas are implemented but an investigation of the company's production process is necessary to achieve correct results. The newly constructed model mostly contains estimates of costs related to production time and material. If these estimates are updated with correct values Hofpartner has the possibility to achieve very reasonable results in their model.

Este trabalho foi desenvolvido como parte das atividades relacionadas ao projeto de cooperação internacional Brasil-Alemanha intitulado "Bulk metal formed parts for power plants" pertencente ao BRAGECRIM (Iniciativa Brasil-Alemanha para Pesquisa Colaborativa em Tecnologia de Manufatura), realizado em parceria entre o Laboratório de Transformação Mecânica (LdTM) da Universidade Federal do Rio Grande do Sul e o Instituto de Conformação Mecânica (IBF) da Universidade Técnica de Aachen (RWTH), Alemanha. Este projeto visa o desenvolvimento do processo de forjamento a quente em matriz aberta para a produção de um eixo vazado para aplicação em aerogeradores de energia, em substituição à eixos maciços usualmente obtidos por fundição, visando aumento de desempenho mecânico e redução de peso da estrutura. Neste trabalho buscou-se analisar, por meio de simulação numérica computacional empregando o método de elementos finitos, diferentes parâmetros de forjamento, de modo a indicar a configuração operacional que se mostra mais adequada para a produção de um eixo vazado para a aplicação pretendida. Para isto, foram realizados cinco experimentos numéricos, avaliando a influência de parâmetros de forjamento na qualidade do produto forjado. Alguns parâmetros analisados foram: a sequência operacional de forjamento, geometrias e combinações de matrizes utilizadas industrialmente, razão de mordida, etc. Para as simulações termomecânicas foi utilizado o software de Elementos Finitos PEP/Larstran acoplado ao módulo de simulação de microestrutura Strucsim. O material utilizado nas simulações foi o aço DIN 42CrMo4 (AISI 4140). Os resultados mostraram que, dentre as diferentes combinações e geometrias de matrizes analisadas, o emprego de um par de matrizes côncavas, aplicando a sequência operacional-A analisada, tende a propiciar um produto de mais alta qualidade, promovendo maior uniformidade de deformação e microestrutura mais homogênea. Também, a razão de mordida influencia diretamente na qualidade do produto, sendo que uma razão de mordida na ordem de 0,6 induz graus de deformação maiores e mais profundos na peça forjada, ao mesmo tempo em que exige maiores cargas de conformação. Comparativos entre resultados da simulação e resultados experimentais de ensaios de compressão a quente de corpos de prova cilíndricos foram realizados para validação do software de simulação numérica. Os resultados experimentais mostraram que o software de simulação numérica pode prever com boa aproximação o fluxo de material e a evolução microestrutural durante o forjamento a quente do aço DIN 42CrMo4. / This work was developed as a part of the activities related to the international cooperation project between Brazil and Germany titled "Bulk formed metal parts for power plants" belonging to BRAGECRIM (Brazil-Germany Initiative for Collaborative Research in Manufacturing Technology). This project is in partnership between the Metal Forming Laboratory (LdTM) from the Federal University of Rio Grande do Sul (UFRGS) and the Institute of Metal Forming (IBF), from Technical University of Aachen (RWTH), Germany. The project aims the development of an open die forging process to produce a hollow shaft for application in wind turbines, replacing the solid shafts usually obtained by casting, in order to increase the mechanical performance and providing weight reduction to wind turbines. The present work aimed to analyze different forging parameters, using Finite Element Method, in order to indicate most suitable forging configuration to the production of a hollow shaft. Five numerical experiments were performed, evaluating the influence of various forging parameters on the quality of the forged product, such as the forging sequence, tool geometries and tool combinations and bite ratio. For thermomechanical simulations the Finite Element software PEP/Larstran was used, coupled to the microstructure simulation module Strucsim. The material used for the numerical simulations was the DIN 42CrMo4 steel (AISI 4140). The results showed that, among the different parameters analyzed, the use of concave dies, applying the operational sequence-A, tends to provide a forged with higher quality, promoting uniform strain distribution and homogeneous microstructure. Also, results showed that a bite ratio around 0,6 provides higher and deeper strain degrees, but requires higher forming loads. Hot compression tests using cylindrical specimens were performed to validate the numerical simulation software, including microstructure evolution. Comparison between simulation and experimental results showed that the numerical simulation software can predict with good approximation the material flow and microstructure evolution during hot forging for DIN 42CrMo4 steel.

Este trabalho foi desenvolvido como parte das atividades relacionadas ao projeto de cooperação internacional Brasil-Alemanha intitulado "Bulk metal formed parts for power plants" pertencente ao BRAGECRIM (Iniciativa Brasil-Alemanha para Pesquisa Colaborativa em Tecnologia de Manufatura), realizado em parceria entre o Laboratório de Transformação Mecânica (LdTM) da Universidade Federal do Rio Grande do Sul e o Instituto de Conformação Mecânica (IBF) da Universidade Técnica de Aachen (RWTH), Alemanha. Este projeto visa o desenvolvimento do processo de forjamento a quente em matriz aberta para a produção de um eixo vazado para aplicação em aerogeradores de energia, em substituição à eixos maciços usualmente obtidos por fundição, visando aumento de desempenho mecânico e redução de peso da estrutura. Neste trabalho buscou-se analisar, por meio de simulação numérica computacional empregando o método de elementos finitos, diferentes parâmetros de forjamento, de modo a indicar a configuração operacional que se mostra mais adequada para a produção de um eixo vazado para a aplicação pretendida. Para isto, foram realizados cinco experimentos numéricos, avaliando a influência de parâmetros de forjamento na qualidade do produto forjado. Alguns parâmetros analisados foram: a sequência operacional de forjamento, geometrias e combinações de matrizes utilizadas industrialmente, razão de mordida, etc. Para as simulações termomecânicas foi utilizado o software de Elementos Finitos PEP/Larstran acoplado ao módulo de simulação de microestrutura Strucsim. O material utilizado nas simulações foi o aço DIN 42CrMo4 (AISI 4140). Os resultados mostraram que, dentre as diferentes combinações e geometrias de matrizes analisadas, o emprego de um par de matrizes côncavas, aplicando a sequência operacional-A analisada, tende a propiciar um produto de mais alta qualidade, promovendo maior uniformidade de deformação e microestrutura mais homogênea. Também, a razão de mordida influencia diretamente na qualidade do produto, sendo que uma razão de mordida na ordem de 0,6 induz graus de deformação maiores e mais profundos na peça forjada, ao mesmo tempo em que exige maiores cargas de conformação. Comparativos entre resultados da simulação e resultados experimentais de ensaios de compressão a quente de corpos de prova cilíndricos foram realizados para validação do software de simulação numérica. Os resultados experimentais mostraram que o software de simulação numérica pode prever com boa aproximação o fluxo de material e a evolução microestrutural durante o forjamento a quente do aço DIN 42CrMo4. / This work was developed as a part of the activities related to the international cooperation project between Brazil and Germany titled "Bulk formed metal parts for power plants" belonging to BRAGECRIM (Brazil-Germany Initiative for Collaborative Research in Manufacturing Technology). This project is in partnership between the Metal Forming Laboratory (LdTM) from the Federal University of Rio Grande do Sul (UFRGS) and the Institute of Metal Forming (IBF), from Technical University of Aachen (RWTH), Germany. The project aims the development of an open die forging process to produce a hollow shaft for application in wind turbines, replacing the solid shafts usually obtained by casting, in order to increase the mechanical performance and providing weight reduction to wind turbines. The present work aimed to analyze different forging parameters, using Finite Element Method, in order to indicate most suitable forging configuration to the production of a hollow shaft. Five numerical experiments were performed, evaluating the influence of various forging parameters on the quality of the forged product, such as the forging sequence, tool geometries and tool combinations and bite ratio. For thermomechanical simulations the Finite Element software PEP/Larstran was used, coupled to the microstructure simulation module Strucsim. The material used for the numerical simulations was the DIN 42CrMo4 steel (AISI 4140). The results showed that, among the different parameters analyzed, the use of concave dies, applying the operational sequence-A, tends to provide a forged with higher quality, promoting uniform strain distribution and homogeneous microstructure. Also, results showed that a bite ratio around 0,6 provides higher and deeper strain degrees, but requires higher forming loads. Hot compression tests using cylindrical specimens were performed to validate the numerical simulation software, including microstructure evolution. Comparison between simulation and experimental results showed that the numerical simulation software can predict with good approximation the material flow and microstructure evolution during hot forging for DIN 42CrMo4 steel.