Thesis (Ph. D.)--University of Oregon, 2004. / Vita. Includes bibliographical references (leaves 178-188). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 178-188). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 265-276).

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

The purpose of this thesis is to conduct a detailed examination of the forward-directivity characteristics of near-fault ground motions produced in the 2010-11 Canterbury earthquakes, including evaluating the efficacy of several existing empirical models which form the basis of frameworks for considering directivity in seismic hazard assessment. A wavelet-based pulse classification algorithm developed by Baker (2007) is firstly used to identify and characterise ground motions which demonstrate evidence of forward-directivity effects from significant events in the Canterbury earthquake sequence. The algorithm fails to classify a large number of ground motions which clearly exhibit an early-arriving directivity pulse due to: (i) incorrect pulse extraction resulting from the presence of pulse-like features caused by other physical phenomena; and (ii) inadequacy of the pulse indicator score used to carry out binary pulse-like/non-pulse-like classification. An alternative ‘manual’ approach is proposed to ensure 'correct' pulse extraction and the classification process is also guided by examination of the horizontal velocity trajectory plots and source-to-site geometry. Based on the above analysis, 59 pulse-like ground motions are identified from the Canterbury earthquakes , which in the author's opinion, are caused by forward-directivity effects. The pulses are also characterised in terms of their period and amplitude. A revised version of the B07 algorithm developed by Shahi (2013) is also subsequently utilised but without observing any notable improvement in the pulse classification results. A series of three chapters are dedicated to assess the predictive capabilities of empirical models to predict the: (i) probability of pulse occurrence; (ii) response spectrum amplification caused by the directivity pulse; (iii) period and amplitude (peak ground velocity, PGV) of the directivity pulse using observations from four significant events in the Canterbury earthquakes. Based on the results of logistic regression analysis, it is found that the pulse probability model of Shahi (2013) provides the most improved predictions in comparison to its predecessors. Pulse probability contour maps are developed to scrutinise observations of pulses/non-pulses with predicted probabilities. A direct comparison of the observed and predicted directivity amplification of acceleration response spectra reveals the inadequacy of broadband directivity models, which form the basis of the near-fault factor in the New Zealand loadings standard, NZS1170.5:2004. In contrast, a recently developed narrowband model by Shahi & Baker (2011) provides significantly improved predictions by amplifying the response spectra within a small range of periods. The significant positive bias demonstrated by the residuals associated with all models at longer vibration periods (in the Mw7.1 Darfield and Mw6.2 Christchurch earthquakes) is likely due to the influence of basin-induced surface waves and non-linear soil response. Empirical models for the pulse period notably under-predict observations from the Darfield and Christchurch earthquakes, inferred as being a result of both the effect of nonlinear site response and influence of the Canterbury basin. In contrast, observed pulse periods from the smaller magnitude June (Mw6.0) and December (Mw5.9) 2011 earthquakes are in good agreement with predictions. Models for the pulse amplitude generally provide accurate estimates of the observations at source-to-site distances between 1 km and 10 km. At longer distances, observed PGVs are significantly under-predicted due to their slower apparent attenuation. Mixed-effects regression is employed to develop revised models for both parameters using the latest NGA-West2 pulse-like ground motion database. A pulse period relationship which accounts for the effect of faulting mechanism using rake angle as a continuous predictor variable is developed. The use of a larger database in model development, however does not result in improved predictions of pulse period for the Darfield and Christchurch earthquakes. In contrast, the revised model for PGV provides a more appropriate attenuation of the pulse amplitude with distance, and does not exhibit the bias associated with previous models. Finally, the effects of near-fault directivity are explicitly included in NZ-specific probabilistic seismic hazard analysis (PSHA) using the narrowband directivity model of Shahi & Baker (2011). Seismic hazard analyses are conducted with and without considering directivity for typical sites in Christchurch and Otira. The inadequacy of the near-fault factor in the NZS1170.5: 2004 is apparent based on a comparison with the directivity amplification obtained from PSHA.

The prediction of motion of slowly moving landslides, also referred to as creeping slopes, is important for the reduction of landslide hazards. Such continuous and slowly moving landslides do not represent the usual stability problems of geotechnical analysis because these slopes are neither still nor ruptured but they move. For proper modeling of the motion of landslides, it is essential to develop improved techniques that integrate appropriate modeling of geological materials involved, laboratory and field tests, and verifications using computational methods. This dissertation focusses attention on the development of such an appropriate model for the time-dependent behavior of creeping landslides. Based on field observations it is proposed that the phenomenon of creeping landslides can be considered as involving the motion of a large mass of soil over a parent (fixed) mass with pronounced shear deformations occuring in a thin layer between the moving mass and the parent mass. The thin layer is refered to as interface zone while the overlying mass is refered to as solid body. The generalized Hierarchical Single Surface (HiSS) series of plasticity models are adopted to characterize the solid body. The interface zone is modeled using the specialization of the HiSS models for conditions occuring in the thin layer. Time dependency is introduced in constitutive models by adopting Perzyna's elastoviscoplastic formulation. The parameters for the HiSS and interface models are determined from laboratory tests on soils obtained from an actual slowly moving landslide at Villarbeney in Switzerland. Triaxial tests along various stress paths and oedemeter tests are conducted for the solid body. New analytical solutions are derived for prediction of oedometer tests. A general procedure for determination of viscous parameters is developed and techniques to process raw creep test data are proposed. Novel and representative simple shear interface tests are conducted to find parameters for the interface model. Special techniques for experimental analysis have been developed. A modified interface model to simulate the observed phenomenon of only compaction under shear is proposed. The parameters for the constitutive models are verified by numerically backpredicting experimental tests. An existing finite element code has been modified to incorporate various aspects of the small strain elastoviscoplastic formulation. Field measurements in the form of inclinometer profiles at various borehole locations on Villarbeney landslide are available. These inclinometer profiles are predicted using the proposed model. A comparison of the field measurements and the results from finite element analysis shows that such a model can be successfully used for predicting the behavior of slowly moving landslides.

O objetivo deste trabalho foi identificar na cadeia produtiva do camarão Litopenaeus vannamei os perigos à saúde animal e à saúde pública e as respectivas medidas de controle, a partir de levantamentos bibliográficos. Os principais perigos à saúde animal identificados foram os vírus da Mancha Branca, Cauda Amarela, Mionecrose Infecciosa, síndrome da Taura e bactérias hepatonecrosantes dos camarões, que ocasionam grandes prejuízos para a cadeia produtiva, devido à queda da produtividade e às elevadas taxas de mortalidade. Esses perigos apresentam riscos à saúde animal, quando se mantêm viáveis nas plantas de cultivo, decorrente das práticas inadequadas de manejo sanitário e da queda de qualidade da água nos viveiros. Quanto aos riscos à saúde humana, alguns patógenos como: Vibrio spp, Salmonella spp e Staphylococcus aureus apresentam perigo se presente e viável no camarão contaminado. O uso abusivo e indiscriminado de metabissulfito de sódio em diferentes concentrações nas plantas de processamento, de contaminantes inorgânicos e resíduos de medicamentos veterinários nas criações podem resultar em níveis elevados de toxicidade aos animais e ao ambiente, precisando, consequentemente ser corrigido com a adoção de boas práticas de manejo do ambiente, implantação de vazio sanitário e estabelecimento de parâmetros microbiológicos e ambientais nos viveiros. Por ser uma atividade promissora para o desenvolvimento socioeconômico do país, é de extrema importância a adoção de medidas de controle destes perigos, que incluem a aplicação dos princípios das "Boas Práticas" e da "Análise de Perigos e Pontos Críticos de Controle" no manejo ambiental e sanitário em todos os elos da cadeia produtiva, dos criatórios até o consumo. / The objetive of this study was to identify in the production chain of shrimp Litopenaeus vannamei the hazards to animal health and public health and their control measures, from the literature. The main hazards to animal health were identified: viruses White Spot, Yellow Tail, Infectious Myonecrosis, Taura syndrome and Hepatonecrotysing bacteria of prawns, which promote large losses in the supply chain due to a drop in productivity and high mortality rates. They are considered dangerous to animal and human health, because they maintain viable pathogens in crop plants, resulting from inadequate health management practices and falling water quality in the ponds. In relation to chemical hazards, the indiscriminate use of sodium metabisulphite, inorganic contaminants and residues of veterinary drugs and pesticides can result in situations of high toxicity to animals and the environment, and must be controlled by adopting good environmental management practices, implementation of depopulation and the establishment of microbiological parameters and environmental conditions in nurseries. Physical hazards can be related to any failure in the process of industrialization and commercialization, in which the detection of foreign objects should be checked by visual inspection and the use of metal detectors. Since it is a promising socio-economic development of the country, it is extremely important to adopt measures to control these hazards, including the principles of " Good Practice" and "Hazard Analysis and Critical Control Points " in the management of environment and health in all links in the production chain, from the farms to the consumers.

The cyclic resistance of predominantly fine-grained soils has received considerable attention following ground and foundation failures at sites underlain by silt-rich soils during recent earthquakes. In several cases substantial ground deformation and reduced bearing capacity of silt soils has been attributed to excess pore pressure generation during cyclic loading. These field case studies are significant due to the occurrence of liquefaction related phenomena in soils that would be characterized as not susceptible to liquefaction using current geotechnical screening criteria. The most widely used of these criteria, the "Chinese Criteria" and its derivatives, are based solely on soil composition and they are essentially diagnostic tools that categorize the soil in a binary fashion as either liquefiable or non-liquefiable. The most significant limitations of these screening tools are that they fail to account for the characteristics of the cyclic loading. This investigation was undertaken to elucidate the potential for strain development in silts during cyclic loading, and to develop a practice-oriented procedure for evaluating the seismic performance of silts as a function of material properties, in situ stresses, and the characteristics of the cyclic loading. This dissertation presents the results of a multi-faceted investigation of the potential for seismically induced pore pressures and large strain development in silt soils. The primary focus of the research was on the synthesis of laboratory testing results on fine grained soils. Laboratory data from cyclic tests performed at Oregon State University and other universities formed the basis for enhanced screening criteria for potentially liquefiable silts. This data was supplemented with field data from sites at which excess pore pressure generation, liquefaction, and/or ground failures were observed during recent earthquakes. This investigation specifically addressed the behavior of silts during loading in cyclic triaxial tests due to the relative abundance of data obtained for this test. The data was used in conjunction with standard geotechnical index tests to enhance an existing energy based procedure for estimating excess pore pressure generation in silts. This pore pressure model can be used with the uncoupled, stress-based methods for estimating the post-cyclic loading volumetric strain developed in this investigation. The energy-based excess pore pressure model and empirical volumetric strain relationship were used to calibrate for applications involving silt soils a nonlinear, effective stress model for dynamic soil response (SUMDES). The SUMDES model was employed, along with the equivalent linear total stress model SHAKE, to estimate excess pore pressures generated at un-instrumented field sites that have exhibited evidence of liquefaction during recent earthquakes. A comparison of the SUMDES and SHAKE results highlighted the limitations of the latter model for simulating dynamic soil response at various levels of shaking and pore pressure response. The results of the SUMDES modeling at several well documented case study sites are presented in this dissertation. These comparisons are valuable for demonstrating the uncertainties associated with modeling of the effective stress behavior of silt during seismic loading. / Graduation date: 2005

Thesis (Ph. D.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2003. / Includes bibliographical references.