O processo de liquefação hidrotermal (HTL) pode converter diversos tipos de biomassa em óleo bruto. Além do produto principal, é gerado um efluente (PHWW) com elevada carga orgânica, quantidades altas de nutrientes e compostos tóxicos. Para lidar com este tipo efluente tem-se sugerido a combinação de tratamentos físico-químicos e biológicos. O objetivo deste estudo foi avaliar a aplicação de processos oxidativos (por H2O2 e fotocatálise com TiO2) e digestão anaeróbia no tratamento do efluente da liquefação hidrotermal de Spirulina. Inicialmente caracterizou-se o efluente em termos de carga orgânica, nutrientes e compostos nitrogenados cíclicos (CNC). Posteriormente, avaliou-se a concentração de oxidante e o tempo de reação no processo de oxidação com H2O2. O tratamento fotocatalítico foi então avaliada no tratamento do efluente em questão, isoladamente, em sequência e combinada ao processo de oxidação por ação de H2O2. Finalmente combinaram-se os processos de oxidação por ação de H2O2 e digestão anaeróbia no tratamento de efluente de PHWW. O efluente da liquefação hidrotermal de Spirulina apresentou elevada carga orgânica, pH alcalino e concentrações altas de nutrientes (nitrogênio e fósforo). Verificou-se também a presença de CNC como pirazinas, δ-valerolactama, caprolactama e butirolactama. A aplicação do processo oxidativo por H2O2 no tratamento de PHWW apresentou efeitos positivos, principalmente para a descoloração que atingiu 93,8 %. A eficiência máxima de remoção de DQO foi de 15,3%. Foi percebida também redução nas concentrações dos CNC. A eficiência do processo de oxidação avançada por fotocatálise e H2O2 foi maior do que obtida quando estes processos foram aplicados separadamente. A aplicação dos processos combinados apresentou eficiência de remoção de cor e DQO semelhante às obtidas quando os processos foram aplicados em sequência, propiciando economia de tempo de reação. Por fim, verificou-se que a digestão anaeróbia do efluente pré-tratado com H2O2 apresentou maior produção de CH4 e remoção de matéria orgânica quando comparada com a digestão anaeróbia que o efluente in natura. Assim, conclui-se a utlização de processos oxidativos avançados ou a combinação da oxidação por H2O2 com a digestão anaeróbia são alternativas promissoras para o tratamento da PHWW. / The hydrothermal liquefaction process (HTL) can convert various types of biomass into bio-crude oil. In addition to the main product, wastewater (PHWW) is generated with high organic content, high amounts of nutrients and toxic compounds. To cope with this type of wastewater the combination of physicochemical and biological treatments has been suggested. The aim of this study was to evaluate the application of oxidative processes (using H2O2 and photocatalysis with TiO2) and anaerobic digestion in the treatment of hydrothermal liquefaction of Spirulina wastewater. Firstly, PHWW was characterized in terms of organic matter, nutrients and nitrogen heterocyclic compounds (CNC) concentrations. Secondly, the oxidant concentration and the reaction time in the oxidation process using H2O2 was evaluated. Photocatalytic treatment was then tested isolated, in sequence and combinated with the oxidation processo using H2O2. Finally, oxidation with H2O2 and anaerobic digestion were combinated and evaluated. The PHWW showed high organic load, alkaline pH and high concentrations of nutrients (nitrogen and phosphorus). The presence of CNC as pyrazines, δ-valerolactam, caprolactam and butyrolactam was also verified. The application of the oxidative process using H2O2 showed positive effects mainly for color removal, which reached 93.8%. The maximum efficiency of COD removal was 15.3%. Reduction in CNC concentrations was also observed . The efficiency of the advanced oxidation process (by combining photocatalysis and H2O2) was greater than that obtained when these processes were applied separately. The application of the combined process presented color and COD removal efficiencies similar to those obtained when the processes were applied in sequence, allowing reaction time savings. Finally, the anaerobic digestion of pre-treated (with H2O2) PHWW showed a greater CH4 production and higher organic matter removal, compared to anaerobic digestion of in natura PHWW. Thus it is possible to conclude that the utlization of advanced oxidation processes or the combination of oxidation with H2O2 and anaerobic digestion are promising alternatives for the treatment of PHWW.

Este trabalho tem como objetivo analisar a tecnologia do ciclo refrigerante misto para obtenção de gás natural liquefeito (GNL). Nessa tecnologia, o GNL é obtido por meio do seu resfriamento através de um ciclo de refrigeração, cujo fluido refrigerante é formado por uma mistura de diversos componentes. O ciclo de refrigeração é usado para resfriar a corrente de gás natural até as condições criogênicas por meio de um trocador de calor. A determinação da composição ótima dessa mistura de refrigerantes é de suma importância para a correta e eficiente operação da planta. O modelo termodinâmico para o cálculo de equilíbrio de fases dos componentes da mistura refrigerante é o baseado na Lei de Raoult, válido para misturas e soluções ideais. Inicialmente, revisam-se os conceitos de refrigerantes mistos, curvas compostas e o ponto de pinça (pinch point), utilizados na implementação da solução computacional. A aplicação dos modelos de gás e solução ideal influencia nos resultados, mas, não obstante, produz bons resultados como os obtidos no presente trabalho. A operação eficiente do ciclo depende, sobretudo, de três parâmetros principais, quais sejam: vazão da mistura refrigerante, razão de pressões alta e baixa do ciclo de refrigeração e composição da mistura refrigerante. Da análise dos resultados obtidos conclui-se que a alteração nas proporções da composição do refrigerante muda significativamente a forma das curvas composta quente e composta fria, quando comparados à alteração dos níveis de pressão e da vazão do ciclo refrigerante. Entretanto, a operacionalização do ciclo somente ocorre se um dado conjunto de valores daqueles parâmetros satisfaça uma determinada diferença mínima de temperatura, ou ponto de pinça, entre as curvas composta quente e composta fria dentro do trocador de calor. Assim, a operação eficiente do ciclo de refrigeração requer a otimização daqueles três parâmetros operacionais. / This work has the objective of analyzing the technology of mixed refrigerant cycle for obtaining liquefied natural gas (LNG). In that technology, the liquefied natural gas is obtained by means of cooling through a refrigeration cycle, whose fluid refrigerant is formed by a mixture of various components. The refrigeration cycle is used to cool the natural gas stream to cryogenic condition with the use of a heat exchanger. The determination of the optimal composition of this refrigerant mixture is very important for the correct and efficient operation of the plant. The thermodynamic model for the equilibrium phase calculation of the refrigerant mixture is based on the Law of Raoult, which is valid for ideal mixtures and solutions. Initially, the concepts of refrigerant mixture, composite curves and pinch point used in the implementation of the numerical solution were reviewed. The application of ideal-gas and ideal-solution models has influence on the results. Nevertheless, it produces good results as those obtained in the present work. The efficient operation of the cycle depends essentially of three key parameters, which are: refrigerant flow rate, the ratio of high to low pressures of the refrigerant cycle and the mixed refrigerant composition. The results indicated that the composition variation of the refrigerant changes significantly the shape of hot and cold composite curves in comparison to the modification in the pressure levels and the refrigerant flow rate of the refrigerant cycle. However, the process will operate only if a given set of values of those parameters satisfies a minimum temperature difference, or pinch point, between the hot and cold composite curves within the heat exchanger. Thus, the efficient operation of the refrigerant cycle requires the optimization of those three operational parameters.

[pt] O estudo do comportamento de solos sob carregamento sísmico é de grande importância para o projeto de geoestruturas situadas em regiões de alta atividade sísmica, como nos países andinos ao longo da borda da placa tectônica sul-americana. No Brasil, localizado no interior desta placa, onde eventos sísmicos são menos frequentes e de menor magnitude, um projeto dísmico detalhado é necessário para algumas obras de engenharia de alta importância como centrais nucleares. O objetivo principal desta dissertação é investigar o comportamento sísmico de geoestruturas, descrevendo e discutindo os vários pontos que devem ser cuidadosamente considerados pelos projetistas sob ponto de vista da engenharia geotécnica. Em particular, o comportamento de um cais para submarinos nucleares, projetado para ser construído no litoral do estado do Rio de Janeiro - Brasil, é analisado considerando aspectos relacionados com o potencial de liquefação dinâmica e a resposta sísmica dos solos em termos de histórias de aceleração, espectros de resposta e deslocamentos permanentes. O modelo constitutivo UBCSAND foi usado para representar a resposta de liquefação de areais saturas sob carregamento cíclico e alguns programs computationais (FLAC, SHAKE2000) foram empregados para calcular as respostas esperadas das geoestruturas. / [en] The study of the soil behaviour under seismic loading is of great importance for the design of geostructures situated in regions of high seismic activity such as in the Andean countries along the border of the South American tectonic plate. In Brazil, situated in the interior of this plate, where seismic events are less frequent and of the smaller magnitude, a detailed seismic design is necessary for some engineering works of high importance such as nuclear power plants. The main objective of this thesis is to investigate the seismic behaviour of geostructures, describing and discussing the several points that should be carefully considered by the designers under the geotechnical engineering standpoint. In particular, the behavior of a nuclear wharf planned to be built on the seashore of the state of Rio de Janeiro - Brazil, is analyzed considering aspects related to the potential of dynamic soil liquefaction and the seismic response of soils in terms of accelerations histories, response spectra and permanent displacements. The UBCSAND constitutive model was used to represent the liquefaction response of saturated sands under cyclic loading and some computational programs (FLAC, SHAKE2000) were used in order to calculate the expected response of the geostrucures.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20684号 / 工博第4381号 / 新制||工||1681(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 澤田 純男, 教授 清野 純史, 准教授 後藤 浩之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Characterization of the seismic hazard and ground-failure hazard of a site using traditional empirical lateral spread displacement models requires consideration of uncertainties in seismic loading, site conditions, and model prediction. Researchers have developed performance-based design methods to simultaneously account for these sources of uncertainty through the incorporation of a probabilistic analytical framework. While these methods can effectively handle the various sources of uncertainty associated with empirical lateral spread displacement prediction, they can be difficult for engineers to perform in a practical manner without the use of specialized numerical tools. To make the benefits of a performance-based approach accessible to a broader audience of geotechnical engineers, a simplified performance-based procedure is introduced in this paper. This map-based procedure utilizes a reference soil profile to provide hazard-targeted reference displacements across a geographic area. Equations are provided for engineers to correct those reference displacements for site-specific soil conditions and surface geometry to produce site-specific, hazard-targeted estimates of lateral spread displacement. The simplified performance-based procedure is validated through a comparative study assessing probabilistic lateral spread displacements across several cities in the United States. Results show that the simplified procedure closely approximates the results from the full performance-based model for all sites. Comparison with deterministic analyses are presented, and the place for both in engineering practice are discussed.

Lateral spread is a seismic hazard associated with soil liquefaction in which permanent deformations are developed within the soil profile due to cyclic mobility. Lateral spread has historically been one of the largest causes of earthquake-related damage to infrastructure. One of the infrastructure components most at risk from lateral spread is that of deep foundations. Because performance-based engineering is increasingly becoming adopted in earthquake engineering practice, it would be beneficial for engineers and researchers to have a performance-based methodology for computing pile performance during a lateral spread event. This study utilizes the probabilistic performance-based framework developed by the Pacific Earthquake Engineering Research Center to develop a methodology for computing probabilistic estimates of kinematic pile response. The methodology combines procedures familiar to most practicing engineers such as probabilistic seismic hazard analysis, empirical compution of lateral spread displacement, and kinematic pile response using p-y soil spring models (i.e. LPILE). The performance-based kinematic pile response model is applied to a series of lateral spread case histories from the earthquake that struck the Limon province of Costa Rica on April 22, 1991. The M7.6 earthquake killed 53 people, injured another 193 people, and disrupted an estimated 30-percent of the highway pavement and railways in the region due to fissures, scarps, and soil settlements resulting from liquefaction. Significant lateral spread was observed at bridge sites throughout the eastern part of Costa Rica near Limon, and the observed structural damage ranged from moderate to severe. This study identified five such bridges where damage due to lateral spread was observed following the earthquake. A geotechnical investigation is performed at each of these five bridges in an attempt to back-analyze the soil conditions leading to the liquefaction and lateral spread observed during the 1991 earthquake, and each of the five resulting case histories is developed and summarized. The results of this study should make a valuable contribution to the field of earthquake hazard reduction because they will introduce a procedure which will allow engineers and owners to objectively evaluate the performance of their deep foundation systems exposed to kinematic lateral spread loads corresponding to a given level of risk.

Stone columns are an established method of liquefaction mitigation in clean sands (fines content <15%). Although stone columns are considered less effective in silty soils, an increase in the area replacement ratio or the addition of wick drains may still produce improvement in the normalized blow count. Limited case histories are available with a direct comparison of the use of stone columns with and without wick drains at one location. The Salmon Lake Dam Modification project provided such a scenario. Two test sections were completed at the site prior to construction to determine the area replacement ratio for the final design as well as to compare the application of stone columns with and without wick drains. Visual observations of water and air escaping from wick drains within a distance of 15 ft of the stone column construction confirmed that drains aided in pore pressure dissipation. Test results indicated that stone column treatment with wick drains produced greater improvement in blow count than stone column treatment without drains. For the overall site, there was an increase in improvement ranging from 3 to 8 SPT blow counts. When compared to the results of a similar evaluation of a site in Ogden, Utah, which had a comparable fines content and an area replacement ratio of 26%, the increase in stone column effectiveness produced by adding wick drains was lower at the Salmon Lake Dam site. The increase in improvement at the Ogden, Utah site ranged from 12 to 18 SPT blow counts. At the Ogden site, wick drains were placed between every stone column while they were only placed between vertical rows of columns at Salmon Lake dam. Despite the beneficial effects provided by using wick drains with stone column treatment in silty soils, the performance was below what would be expected for stone column treatment without wick drains in clean sands with less than 15% fines. Stone column treatment also proved less effective in layers of sandy silt than in layers of silty sand, which was indicated by lower average improvement and more points of negative improvement in layers of sandy silt. Although several different area replacement ratios were analyzed (23, 27, 31, and 35%), no consistent trend towards greater improvement in blow count was seen as the replacement ratio increased beyond 23%.

This research consists of full-scale shake table tests to investigate liquefaction of sandy soils. Consideration of the potential and consequences of liquefaction is critical to the performance of any structure built in locations of high seismicity underlain by saturated granular materials as it is the leading cause of damage associated with ground failure. In certain cases the financial losses associated with liquefaction can significantly impact the financial future of an entire region. Most liquefaction triggering studies are performed in the field where liquefaction has been previously observed, or in tabletop laboratory testing. The study detailed herein is a controlled laboratory test performed at full scale to allow for the measurement of field-scale index testing before and after cyclic loading. Testing was performed at the Parson’s geotechnical and Earthquake Laboratory at Cal Poly San Luis Obispo on the 1-dimensional shake table with a mounted flexible walled testing apparatus. The testing apparatus, originally constructed for soil-structure interaction experiments utilizing soft clay was retrofitted for the purpose of studying liquefaction. This research works towards comparing large-scale simple-shear liquefaction testing to small-scale simple-shear liquefaction testing of a #2/16 Monterey sand specimen. The bucket top was modified in order to apply a vertical load to the soil skeleton to replicate overburden soil conditions. Access ports were fitted into the bucket top for instrument cable access and to allow cone penetration testing before and after cyclic loading. A shear-wave generator was created to propagate shear waves into the sample for embedded accelerometers to measure small strain stiffness of the sample. Pore-pressure transducers were embedded in the soil sample to capture excess pore water pressure produced during liquefaction. Displacement transducers were attached to the bucket in order to measure shear strains during cyclic testing and to measure post-liquefaction volumetric deformations. The results of this investigation provide an empirical basis to the behavior of excess pore water production, void re-distribution, shear wave velocity, shear strain and cone penetrometer tip resistance of #2/16 Monterey sand before, during, and after liquefaction in a controlled laboratory environment at full-scale.

Liquefaction-induced lateral spread displacements cause severe damage to infrastructure, resulting in large economic losses in affected regions. Predicting lateral spread displacements is an important aspect in any seismic analysis and design, and many different methods have been developed to accurately estimate these displacements. However, the inherent uncertainty in predicting seismic events, including the extent of liquefaction and its effects, makes it difficult to accurately estimate lateral spread displacements. Current conventional methods of predicting lateral spread displacements do not completely account for uncertainty, unlike a performance-based earthquake engineering (PBEE) approach that accounts for the all inherent uncertainty in seismic design. The PBEE approach incorporates complex probability theory throughout all aspects of estimating liquefaction-induced lateral spread displacements. A new fully-probabilistic PBEE method, based on results from the cone penetration test (CPT), was created for estimating lateral spread displacements using two different liquefaction triggering procedures. To accommodate the complexity of all probabilistic calculations, a new seismic hazard analysis tool, CPTLiquefY, was developed. Calculated lateral spread displacements using the new fully-probabilistic method were compared to estimated displacements using conventional methods. These comparisons were performed across 20 different CPT profiles and 10 cities of varying seismicity. The results of this comparison show that the conventional procedures of estimating lateral spread displacements are sufficient for areas of low seismicity and for lower return periods. However, by not accounting for all uncertainties, the conventional methods under-predict lateral spread displacements in areas of higher seismicity. This is cause for concern as it indicates that engineers in industry using the conventional methods are likely under-designing structures to resist lateral spread displacements for larger seismic events.

Liquefaction-induced lateral spread displacements cause severe damage to infrastructure, resulting in large economic losses in affected regions. Predicting lateral spread displacements is an important aspect in any seismic analysis and design, and many different methods have been developed to accurately estimate these displacements. However, the inherent uncertainty in predicting seismic events, including the extent of liquefaction and its effects, makes it difficult to accurately estimate lateral spread displacements. Current conventional methods of predicting lateral spread displacements do not completely account for uncertainty, unlike a performance-based earthquake engineering (PBEE) approach that accounts for the all inherent uncertainty in seismic design. The PBEE approach incorporates complex probability theory throughout all aspects of estimating liquefaction-induced lateral spread displacements. A new fully-probabilistic PBEE method, based on results from the cone penetration test (CPT), was created for estimating lateral spread displacements using two different liquefaction triggering procedures. To accommodate the complexity of all probabilistic calculations, a new seismic hazard analysis tool, CPTLiquefY, was developed. Calculated lateral spread displacements using the new fully-probabilistic method were compared to estimated displacements using conventional methods. These comparisons were performed across 20 different CPT profiles and 10 cities of varying seismicity. The results of this comparison show that the conventional procedures of estimating lateral spread displacements are sufficient for areas of low seismicity and for lower return periods. However, by not accounting for all uncertainties, the conventional methods under-predict lateral spread displacements in areas of higher seismicity. This is cause for concern as it indicates that engineers in industry using the conventional methods are likely under-designing structures to resist lateral spread displacements for larger seismic events.