No description available.

No description available.

[Truncated abstract] This research has studied the penetration and extraction resistance profiles of different types of penetrometers in soft clay. The penetrometers of interest include the cone, T–bar, ball and plate. Effects of the surface roughness and aspect ratio of the T–bar penetrometer on its resistance have also been investigated. Undrained shear strength, Su, profiles derived from the penetration tests are compared with the shear strengths measured from field vane shear tests and laboratory (triaxial and simple shear) tests. Both in situ and centrifuge model penetration tests were undertaken for the research. In addition, ‘undisturbed’? tube samples were retrieved from both the field and the centrifuge strongbox samples (after completion of the centrifuge tests) for laboratory testing. The in situ testing was carried out in Western Australia, at the Burswood site near Perth, with tests including cone, T–bar, ball and plate penetrometer tests, and vane shear tests. Interestingly, the T–bar, ball and plate (‘full-flow’) penetrometers showed a narrow band of resistance profiles both during penetration and extraction, with a range of around 15 % between the highest and lowest profiles and standard deviation of 15 %. However, the cone penetrometer gave similar resistance at shallow depths but increasingly higher penetration resistance at depths greater than 7 m – a phenomenon that is also common in offshore results. During extraction, the cone penetrometer gave a higher resistance profile than the full–flow penetrometers for much of the depth of interest. The Su profile measured directly from the vane shear tests falls within the Su profiles derived from the penetration resistances of the full–flow penetrometers, using a single bearing factor, N = 10.5 (the value originally suggested in the literature for a T–bar penetration test). Again, the cone penetrometer demonstrated diverging results, requiring two separate values for the cone factor, Nkt (10.5 initially increasing to 13 for depths below 10 m) in order to give Su similar to the vane shear tests. This highlights the possible variability of the cone factor with depth. Cyclic penetration and extraction tests were performed at specific depths for each fullflow penetrometer. These tests comprised displacement cycles of ±0.5 m about the relevant depth, recording the penetration and extraction resistances over five full cycles. The results may be used to derive the remoulded strength and sensitivity of the soil. Laboratory tests such as triaxial and simple shear tests were performed on ‘undisturbed’ tube samples retrieved from the same site to evaluate the in situ shear strengths in the laboratory. However, the resulting Su data were rather scattered, much of which may be attributed to variable sample quality due to the presence of frequent shell fragments and occasional silt lenses within the test samples. In general, N factors for the full–low penetrometers, back–calculated using Su values measured from the simple shear tests, fell mainly in a range between 9.7 and 12.8 (between 10.4 and 12.2 for the standard size T–bar (250 mm x 40 mm))

Thesis (M.Eng.) -- Memorial University of Newfoundland. / Bibliography : leaves 118-122. Also available online.

Orientador: Carlos Eduardo Angeli Furlani / Coorientador: David Luciano Rosalen / Banca: Rouverson Pereira da Silva / Banca: Denizart Bolonhezi / Resumo: Considerando a importância da cultura de cana-de-açúcar e a intensificação do tráfego de máquinas, o objetivo deste trabalho foi avaliar a resistência mecânica do solo à penetração (RMSP) para comparar o nível de compactação do solo em relação ao número de corte do talhão. As medições de RMSP foram realizadas após a colheita mecanizada e repetidas por quatro anos em três talhões cultivados com a variedade SP 87-365, localizados na fazenda Santa Izabel, região de Jaboticabal, São Paulo. Foi utilizado o penetrômetro eletrônico acoplado a um quadriciclo para medir a RMSP até 50 cm de profundidade em duas regiões, uma próxima à soqueira ou fileira de cana (FC) e outra no centro da entrefileira ou faixa dos rodados (FR). A partir dos dados georreferenciados foram gerados mapas de espacialização da RMSP média das camadas de 1-10, 11-20, 21-30, 31-40 e 41-50 cm de profundidade que permitiram visualizar a distribuição espacial dos valores de RMSP e estimar os níveis de compactação de cada tratamento e de cada camada do perfil do solo amostrado. Os valores médios de RMSP obtidos variaram entre os tratamentos sem seguir uma ordem definida pelo número de cortes, podendo ter sido influenciado pelo teor de água do solo. Ocorreu predominância de valores médios entre 2 e 3 MPa. Quanto à distribuição vertical no perfil do solo, os valores de RMSP foram menores na camada superficial em ambas regiões, aumentando conforme a profundidade em FC, com maiores níveis na camada de 41-50 cm. Em FR os valores maiores ficaram na camada de 11-20 cm. Pôdese concluir que o tráfego de máquinas causou alterações na RMSP / Abstract: Considering the importance of sugarcane production and the intensification of machinery traffic, the aim of this study was evaluate soil mechanical resistance to penetration (SMRP) to compare the level of soil compaction in relation to ratoon cycle. The assessments of RMSP were performed after mechanical harvesting and repeated for four years in three areas cultivated with variety SP 87-365, located at Santa Izabel farm, Jaboticabal, São Paulo. An electronic penetrometer coupled to an ATV was used to measure SMRP up to 50 cm depth in two regions, near ratoon or crop row (FC) and at center of inter-row or traffic track (FR). From georeferenced data it was generated maps of spatial variability of SMRP to layers 1-10, 11-20, 21-30, 31-40 and 41-50 cm of depth that allowed visualization of the spatial distribution of SMRP values and estimate levels of compaction of each treatment and each layer in the soil profile sampled. The average SMRP values obtained varied between treatments without following a defined order according to harvest cycle and may have been influenced by the water content of the soil. There was a predominance of average values between 2 and 3 MPa. Regarding the vertical distribution in soil profile, the values of SMRP were lower in the surface layer in both regions, increasing with depth in FC, with higher levels in the 41-50 cm layer. At FR, values were higher in the 11-20 cm layer. It could be concluded that the traffic of machines caused changes in the MRSP / Mestre

Made available in DSpace on 2015-01-26T13:21:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-08Bitstream added on 2015-01-26T13:30:59Z : No. of bitstreams: 1 000800564.pdf: 2654481 bytes, checksum: 5c8e0ef8280754468760bf32646a4d46 (MD5) / Considerando a importância da cultura de cana-de-açúcar e a intensificação do tráfego de máquinas, o objetivo deste trabalho foi avaliar a resistência mecânica do solo à penetração (RMSP) para comparar o nível de compactação do solo em relação ao número de corte do talhão. As medições de RMSP foram realizadas após a colheita mecanizada e repetidas por quatro anos em três talhões cultivados com a variedade SP 87-365, localizados na fazenda Santa Izabel, região de Jaboticabal, São Paulo. Foi utilizado o penetrômetro eletrônico acoplado a um quadriciclo para medir a RMSP até 50 cm de profundidade em duas regiões, uma próxima à soqueira ou fileira de cana (FC) e outra no centro da entrefileira ou faixa dos rodados (FR). A partir dos dados georreferenciados foram gerados mapas de espacialização da RMSP média das camadas de 1-10, 11-20, 21-30, 31-40 e 41-50 cm de profundidade que permitiram visualizar a distribuição espacial dos valores de RMSP e estimar os níveis de compactação de cada tratamento e de cada camada do perfil do solo amostrado. Os valores médios de RMSP obtidos variaram entre os tratamentos sem seguir uma ordem definida pelo número de cortes, podendo ter sido influenciado pelo teor de água do solo. Ocorreu predominância de valores médios entre 2 e 3 MPa. Quanto à distribuição vertical no perfil do solo, os valores de RMSP foram menores na camada superficial em ambas regiões, aumentando conforme a profundidade em FC, com maiores níveis na camada de 41-50 cm. Em FR os valores maiores ficaram na camada de 11-20 cm. Pôdese concluir que o tráfego de máquinas causou alterações na RMSP / Considering the importance of sugarcane production and the intensification of machinery traffic, the aim of this study was evaluate soil mechanical resistance to penetration (SMRP) to compare the level of soil compaction in relation to ratoon cycle. The assessments of RMSP were performed after mechanical harvesting and repeated for four years in three areas cultivated with variety SP 87-365, located at Santa Izabel farm, Jaboticabal, São Paulo. An electronic penetrometer coupled to an ATV was used to measure SMRP up to 50 cm depth in two regions, near ratoon or crop row (FC) and at center of inter-row or traffic track (FR). From georeferenced data it was generated maps of spatial variability of SMRP to layers 1-10, 11-20, 21-30, 31-40 and 41-50 cm of depth that allowed visualization of the spatial distribution of SMRP values and estimate levels of compaction of each treatment and each layer in the soil profile sampled. The average SMRP values obtained varied between treatments without following a defined order according to harvest cycle and may have been influenced by the water content of the soil. There was a predominance of average values between 2 and 3 MPa. Regarding the vertical distribution in soil profile, the values of SMRP were lower in the surface layer in both regions, increasing with depth in FC, with higher levels in the 41-50 cm layer. At FR, values were higher in the 11-20 cm layer. It could be concluded that the traffic of machines caused changes in the MRSP

No description available.

Knowledge of geotechnical soil properties in the upper meter of the seabed is important for challenges such as scour around submerged structures, management of unexploded ordnances, and generally issues associated with active sediment transport and deposition. Portable free fall penetrometers have been previously used to provide initial information on sediment type, strength, and stratification, but challenges with the calibration of empirical parameters such as the cone factor and strain rate factor hampered the derivation of geotechnical design parameters such as undrained shear strength. This challenge applies particularly in areas of more rare seabed soil conditions such as very soft estuarine sediments. This study aims to advance the analysis procedure of portable free fall penetrometers (PFFP) in soft subaquatic fine-grained soils with natural water contents greater than the liquid limit by estimating the undrained shear strength (su). The logarithmic and power law methods for strain rate correction were investigated at sites in the York River Estuary and yielded a match to vane shear results at a logarithmic multiplier of k=0.1-0.3 and a power law rate exponent of β=0.01-0.03, indicating minimal strain rate effects. Resulting representative cone factors based on sediment strength and profile groupings ranged from 7 to 12 for logarithmic, power law, and no strain correction, and were tested at sites in the Potomac River with similar sediment properties. The PFFP su compared well with mini-vane shear measurements with differences of less than ± 0.5 kPa. Additionally, the PFFP su showed inappreciable differences in strength with or without strain rate application. Therefore, these high water content soils that exhibit little strain rate effects within a soil behavior context, can be better understood through rheological studies. Rheological studies were conducted, and the storage and loss modulus were observed to remain constant when the soil is tested over a range of frequencies. This indicates that the sediment strength is not affected by the rate of soil testing. The outcome of this study is the advanced the use of the PFFP by quantifying the strain rate effects and defining the applicable cone factors for use in estimating the undrained shear strength of soft estuarine marine soils. Furthermore, the understanding of soil behavior of these soils has been explored from rheological context. / Master of Science / Presence of unexploded munitions (UXO) in waterways and coastal environments poses a danger to the populace. UXOs located proud on the seabed can be moved by hydrodynamic forces such as waves and currents to habited areas. This has prompted the need to understand how UXOs interact with the seabed regarding erosion, burial, as well as sinking. Current methods used to detect munitions can lack accuracy from unknown seabed soil conditions. Portable free fall penetrometers (PFFP) are rapid and economical tools that are used to obtain soil information in the seabed. However, the interpretation of the penetrometer data needs to be advanced to get more accurate results of soil strength. In this research, physical soil samples were retrieved and tested in the laboratory. The laboratory results were used to calibrate the PFFP to improve the estimation of soil strength from PFFP. The estuarine soil tested exhibited high water contents raising the question of whether to describe its behavior rather as soil or suspension. Further tests were carried out to study how this soil deforms and flows when a load is applied. The results from this research enable the measuring of strength of the seabed more accurately and improves the understanding of very soft estuarine soil behavior.

Free-fall penetrometers (FFPs) are an attractive tool for the rapid characterization of sediments in the nearshore and coastal areas. To improve their measurement capabilities, modern FFPs can be equipped with pore pressure sensors. Pore pressure measurements are extensively used in traditional cone penetration testing, but their usage and interpretation is still limited for FFP testing. This thesis represents an effort to advance the interpretation of pore pressure measurements from FFP testing. Data was collected using the torpedo-shaped FFP BlueDrop during surveys at Herschel Island, YT, Yakutat, AK, Clay Bank, VA, and Yorktown, VA. Additionally, test deployments in the laboratory were performed in kaolin clay. Data analysis was focused on pore pressure measurements during these deployments. Two major advancements regarding current data analysis of FFP pore pressure measurements were explored: 1) a method based on fluid dynamic principles was proposed to correct the pressure recordings for the dynamic flow effects due to the high-velocity fall and impact. The results show that using Bernoulli’s theorem coupled with the concept of pressure coefficients results in good agreement between measured and hydrostatic pressures during the free-fall and initial penetration stage. 2) Pore pressure dissipation curves measured by the penetrometer at rest at maximum penetration depth were also studied. The mechanisms behind the non-standard dissipation curves were explored. The results suggest that non-standard dissipation curves can be interpreted by correcting according to Sully et al.’s (1999) extrapolation technique. The technique can also be used with data from an unsaturated or clogged filter. / Master of Science / An increasing use of nearshore and offshore areas for the development of infrastructure such as pipelines, cables, renewable energy harvesting devices, and measures against coastal erosion warrants the development of specialized methods for investigating the stability of the seabed. Portable free-fall penetrometers represent a cost-efficient approach to characterize shallow seabed sediments, but there are challenges associated with deriving geotechnical design parameters from these novel instruments. This study aims at developing a better understanding of the pore pressure (the pressure developed in the water in the soil’s voids) data obtained during free-fall penetration testing. The pore pressures developed during the penetration of the penetrometer is dependent on the soil type, and is often used to correlate to it. This study used data obtained from field surveys at Herschel Island, YT, Clay Bank, VA, Yakutat, AK, and Yorktown, VA. Additionally, controlled tests were performed in the laboratory in an instrumented seabed. This study resulted in a novel method to correct the pressure data from the penetrometer for dynamic fluid flow effects and validation of an interpretation technique for dissipation curves to obtain the time required for consolidation, based on initial results.

Free-fall penetrometers (FFP) are useful instruments for the rapid characterization of seabed sediments. However, the interpretation of FFP data remains largely a skilled task. In order to increase the reliability of results obtained using these instruments, in both expert and non-expert hands, it is advantageous to establish well defined and repeatable procedures for instrument use and data interpretation. The purpose of this research was therefore to develop and refine methods for the interpretation of FFP data. Data were gathered with the FFP Nimrod during two surveys following dredging in Sydney Harbour, Nova Scotia. The challenge of interpreting the data from these two surveys in an efficient and consistent manner was the basis of this work and led to the development of new techniques for improving resolution of the mud-line, identifying areas of erosion and deposition, and qualitatively evaluating the consolidation state of cohesive marine sediments. The method developed for improving the resolution of the mud-line simply describes a procedure of combining the data from different accelerometers with different accuracies and ranges to more clearly define the point of impact with the sea-floor. The method developed to evaluate in-situ sediment consolidation state combines theories of self-weight consolidation and ultimate bearing capacity to predict a range of potential bearing capacities for normally consolidated cohesive sediments. Finally, by combining the previous two methods a third method is proposed for locating areas of potential erosion and deposition. / Master of Science / Human interaction with the marine environment takes many forms. For example, in the case of marine/civil engineering projects these interaction may include: erecting off-shore wind turbines, installing oil rigs, and building break waters. All of these activities involve installing structures with foundations on or attached to the seafloor. In order for these structures to be effective and for there foundation to not fail a knowledge of the physical conditions <i>at</i> the seafloor is required. Physical characterization of the seafloor involves describing three interdependent processes: hydrodynamics (the movement of water), morphodynamics (the dynamic processes which shape the seafloor), and sediment dynamics (the movement of sediments). Together, these three form a complex and interacting feedback loop in which a change in one will affect the states of the others and eventually itself. For example, energetic hydrodynamic conditions may erode sediment from the seabed. As this sediment is transported and deposited elsewhere by the flow of water, the initial features which make up the seafloor, such as dunes, ripples, and sand-waves, are reshaped. These forms may grow or shrink, migrate, or be wiped out and replaced entirely. The changed shape of the seabed will then in turn influence the flow of passing waves, tides, and currents. The newly changed flow patterns then restarting the cycle anew. Understanding the interactions of these processes is vital to designing effective engineering works in the marine environment. Free-fall penetrometers (FFP) are useful instruments for the rapid characterization of seabed sediments and can therefore provide information about the sediment dynamics at the seafloor’s surface. However, the interpretation of FFP data remains largely a skilled task. In order to increase the reliability of results obtained using these instruments, in both expert and non-expert hands, it is advantageous to establish well defined and repeatable procedures for instrument use and data interpretation. The purpose of this research was therefore to develop and refine methods for the interpretation of FFP data. During two surveys in Sydney Harbour, Nova Scotia, data were gathered from the seafloor’s surface with the FFP <i>Nimrod</i>. The challenge of interpreting this data in an efficient and consistent manner was the basis of this work and resulted in the development of new methods and techniques for data interpretation and analysis. These methods will allow for the improved characterization of sediment processes and properties at the uppermost seafloor, contributing to a better understanding of the seafloor environment as a whole and improving engineering designs.