The motivation for this study is to create a scaled laboratory model of a steel construction pile being driven by an impact hammer, which can provide controlled data to aid understanding and development of a structural acoustics numerical model simulating full-scale impact pile driving. The scaled model is approximately thirty times shorter than a typical 30-meter long Cast-in-Shell-Steel (CISS) pile. The relationship between the impact force, structural vibrations, and radiated sound field is analyzed. The time-domain acoustic intensity in the radial direction is found to be predominately negative immediately following excitation by the impact force. Analysis of the radial intensity shows that during the hammer strike, there is a net flow of energy from the structure into the water; however, because the structure and water are acoustically coupled a significant portion of the energy immediately flows back into the cylinder following hammer impact. This fluid-structure interaction results in a highly damped acoustic pulse in the water that propagates to the far field. In addition, the frequency spectra of the impact force, model pile wall acceleration in the radial direction in air and water, and underwater acoustic pressure are analyzed to find transfer functions between these variables. The transfer function between impact force and sound pressure is of particular interest because it can be used to calculate the system response for any other applied hammer force. This transfer function analysis has potential applications in mitigating noise generated by impact pile driving.

[Truncated abstract] The Arabian Gulf oil and gas production reserves have made it one of the world's strategic producers since early 1960s, with many of the existing platforms stretched beyond their original design life. Advances in drilling technology and reservoir assessments have extended the requirement for the service life of those existing platforms even further. Extension of the life span of an existing platform requires satisfactory reassessment of its various structural components, including piled foundations. The American Petroleum Institute Recommended Practice 2A (API RP2A) is commonly used in the Arabian Gulf for reassessment of existing platforms. The API guidelines have been developed for conditions in the Gulf of Mexico, the waters off Alaska and the Pacific and Atlantic seaboards of the USA. However, the Arabian Gulf conditions are fundamentally different to those encountered in US waters. Hence, there is a need to develop guidelines for reassessment of existing offshore structures to account for the specific conditions of the Arabian Gulf. This thesis performs statistical analyses on databases collected during this research from existing platforms to calibrate relevant load and resistance factors for the required guidelines. The developed guidelines are based on established approaches used in developing international codes and standards such as API RP2A-LRFD. The outcome of this research revolves around the following three main issues: 1. Calibration of resistance factors for axial capacity of piles driven in the carbonate soils API RP2A (1993, 2000) does not quantify limiting soil parameters for piles driven in carbonate soils and provides a single factor to predict the capacity of piled foundations. This research identifies a set of limiting engineering parameters and calibrates corresponding capacity reduction factors to predict axial capacity of driven piles in the carbonate soils of the Arabian Gulf. ... This contrasts with Section 'R' of API RP2A (1993, 2000), which focuses on extreme environmental conditions when performing reassessment. The probabilities of failure considered in this research do not include errors and omissions (controlled by quality assurance procedures) or material deterioration (controlled by choice of materials, detailing, protective devices, and inspection and repair procedures) or reliability-based maintenance. Addressing operating overload conditions requires attending to two issues, namely the capacity of piles driven in carbonate soils and OALL, which have been addressed in this research. The operational overload situation is likely to occur during shutdown condition or during drilling or work over activities where significant OALL are usually applied to platform decks. Such operational overload can be managed by placing signs at various open areas on the platform nominating the maximum load limits (kPa), introducing procedures that ensure that maximum load limits are not exceeded during operation and management of human behavior by reinforcing the importance of following the procedures. The outcomes of this research are expected to have a profound influence on reassessment of existing platforms in the Arabian Gulf.

The loads applied to pile foundations installed offshore vary greatly from those encountered onshore, with more substantial lateral and torsional loads. For combined axial and lateral loading the current design practice involves applying an axial load to a deep foundation and assessing the pile behaviour and then considering a lateral load separately. For the problem of an altering directions of lateral loads (e.g. due to changes in the wind directions acting on offshore wind turbines) a clear design procedure is not available. There is thus a need for a clearly established methodology to effectively introduce the interaction between the four different loading directions (two lateral, one axial and one torsional). In this thesis, a model is presented that introduces a series of Winkler elasto-plastic elements coupled between the different directions via local interaction yield surfaces along the pile. The energy based method that is used allows the soil-pile system to be defined explicitly using two equations: the energy potential and the dissipation potential. One of the most interesting applications of this model is to piles subjected to a change in lateral loading direction, where the loading history can significantly influence the pile behaviour. This effect was verified by a series of experimental tests, undertaken using the Geotechnical Centrifuge at UWA. The same theory was then applied to cyclic loading in two dimensions, leading to some very useful conclusions regarding shakedown behaviour. A theoretically based relationship was applied to the local yielding behaviour for a pile subjected to a combination of lateral and axial loading, allowing predictions to be made of the influence of load inclination on the pile behaviour. The ability of this model to represent interaction between four degrees of freedom allows a more realistic approach to be taken to this problem than that considered in current design practice.

Este trabalho tem por objetivo fazer um estudo da interação solo-estaca em ambientes submersos. Para as análises foram utilizadas as seguintes condições: dois tipos de estacas, concreto e mista (tubo metálico preenchido com concreto); quatro condições para o solo (arenoso, coesivo e dois solos estratificados); dois casos de carregamento (caso I com cargas vertical, horizontal e momento e caso II somente carga horizontal e momento). Os modelos de cálculo foram gerados no programa SAP2000, sendo a estaca modelada como elemento de barra e solo representado por molas linearmente elásticas espaçadas a cada metro, baseado no modelo de Winkler. Os coeficientes de mola (Ki) foram calculados por três métodos, Terzaghi, Bowles e com equações que correlacionam às propriedades elásticas do solo. Para o solo arenoso, o método escolhido para a aplicação nos modelos de cálculo foi o de Bowles, e para o solo coesivo a equação proposta por Vesic, que correlaciona os valores de Ki com as propriedades elásticas do solo. Os resultados dos modelos de cálculo do SAP2000 mostraram que: as estacas utilizadas nas análises apresentaram o comportamento de estacas flexíveis, no qual tem os seus deslocamentos ocasionados devidos a flexão; a região que mostra o comportamento relevante da estaca, para o solo arenoso e coesivo, está de acordo com as conclusões indicadas pelos pesquisadores Matlock & Reese (1960) e Davisson & Gill (1963); a atuação da carga vertical não exerce influência nos resultados referentes ao comportamento horizontal da estaca; a estaca mista, em função da maior rigidez a flexão (EI), transfere uma tensão menor para o solo que a estaca de concreto. Os resultados dos modelos de cálculo do SAP2000, para os máximos deslocamentos horizontais e momentos fletores, ficaram muito próximos do valores obtidos com o método de Navdocks DM-7 para o solo arenoso. Já para solo coesivo os resultados ficaram próximos dos valores obtidos pelo método clássico da equação diferencial. / This work aims to make a study of the soil-pile interaction in submerged environments. For the analysis we used the following conditions: two types of piles, concrete pile and composite pile (steel pipe filled with concrete), four conditions for the soil (sandy, cohesive and two stratified soil), two load cases (case I with vertical and horizontal loads and moment, case II with horizontal load and moment). The calculation models were generated in the software SAP2000. The pile was modeled as a bar element and the soil represented by linearly elastic springs spaced each meter, based on the model of Winkler. The spring coefficients (Ki) were calculated by three methods, Terzaghi, Bowles and equations that correlates to the elastic properties of the soil. For the sandy soil, the method chosen for applying the model calculations was the Bowles, and for the cohesive soil the equation proposed by Vesic, which correlates with Ki values of the elastic properties of the soil. The results of the model calculations (SAP2000) show that: the piles used in the analysis presented flexible behavior, which have their displacements caused due to bending, the region that shows the relevant behavior of the piles for the sandy and cohesive soil agrees with the conclusions stated by researchers Matlock & Reese (1960) and Davisson & Gill (1963), the performance of vertical load does not influence the results concerning the horizontal behavior of the pile; the composite pile, due to the higher stiffness bending (EI), transfers a lower stress to the soil than a concrete pile. The model calculations results of SAP2000 to the maximum horizontal displacement and bending moments were very close to the values obtained with the method of Navdocks DM-7 to the sandy soil. However, the results for the cohesive soil were close to the values obtained by the classical method of the differential equation.

In the present work, a settlement-based method is proposed to design piled raft foundation. The proposed design method is found to be very efficient, economical and requires less calculation time. Simple software can be used to execute all the interactions and loop calculations.<p>Unlike methods with numerical techniques, there are practically no limitations for the number of individual piles under the raft, size of the group and the group shape or layout. It can also be applied to piles with different length or piles that are located within multi-layered soils.<p>The raft is designed first according to the allowable settlement that is pre-defined by the structural requirements and with the necessary factor of safety. When raft suffers excessive settlement, then the load that causes excess raft settlement beyond the required limit is to be transferred to the fully mobilised frictional piles. <p>The fully mobilised shaft (with no end bearing) piles are designed with factor of safety close to unity since their function is only to reduce raft settlement and since the raft has an adequate bearing capacity.<p>Geometry of these piles is chosen to fully mobilise their shafts capacity with low settlement level in order to comply with load/settlement requirement and reduce raft settlement to the pre-defined level. <p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Impact pile driving can produce extremely high underwater sound levels, which are of increasing environmental concern due to their deleterious effects on marine wildlife. Prediction of underwater sound levels is important to the assessment and mitigation of the environmental impacts caused by pile driving. Current prediction methods are limited and do not account for the dynamic pile driving source, inhomogeneities in bathymetry and sediment, or physics-based sound wave propagation. In this thesis, a computational model is presented that analyzes and predicts the underwater noise radiated by pile driving and is suitable for shallow, inhomogeneous environments and long propagation ranges. The computational model uses dynamic source models from recent developments in the technical literature. Pile source models are coupled to a broadband application of the range-dependent acoustic model (RAMPE), a standard parabolic equation (PE) propagation code capable of modeling wave propagation through complex, range dependent environments. Simulation results are shown to be in good agreement with several observations of pile driving operations in the Columbia River between Portland, Oregon and Vancouver, Washington. The model is further applied to extend sound level predictions over the entire river and study the effects of sediment and bathymetry on the underwater sound levels present in the environment.