Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2005. / Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-20T23:05:03Z No. of bitstreams: 1 Estudo sobre solos arenosos finos lateríticos da planície costeira sul do RS para emprego em pavimentação econômica.pdf: 6063851 bytes, checksum: f0e816d14eb818435e3e10902c863805 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-06-03T18:24:06Z (GMT) No. of bitstreams: 1 Estudo sobre solos arenosos finos lateríticos da planície costeira sul do RS para emprego em pavimentação econômica.pdf: 6063851 bytes, checksum: f0e816d14eb818435e3e10902c863805 (MD5) / Made available in DSpace on 2013-06-03T18:24:06Z (GMT). No. of bitstreams: 1 Estudo sobre solos arenosos finos lateríticos da planície costeira sul do RS para emprego em pavimentação econômica.pdf: 6063851 bytes, checksum: f0e816d14eb818435e3e10902c863805 (MD5) Previous issue date: 2005 / In the Southern Coastal Plain of the RS, the large distances of rock’s transport materials have been making unfeasible the economic paving of roads characterized by the low volume of traffic. Aiming the cost’s reduction, alternatives are looked to substitute the noble materials by local soils in the project and execute of the pavement’s structures. In this dissertation are presented results about the investigation of physical, mineralogical and technological properties of fine sandy soils in a geotechnical grouping denominated “ lateritic sands” (Bastos, 2002). These soils wich constitute the horizon’s subsuperficial profiles of Argissolo Vermelho-Amarelo developed on the Coastal Barrier BII (Pleistocene), with physical and morphologic characteristics similar to the lateritic fine sandy soils (SAFL) found in the southeast of Brazil, they were submitted to the criterion of choice based on MCT Methodology (Villibor and Nogami, 1982). Any researched soils assists in totally the proposal criterion. The ARMAR soil, although presents expansion above the limit of the specification, is the one that presents better acting in support’s capacity, and is the one of the soils that less stands back of the suitable superior limit as the capillary sorption. This fact, ally to the same belong to a commercial’s place, motivated their utilization in the measure ments by the PMSP (PMSP, 1992) method, of the hypothetical pavement structure with base in SAFL accomplished in this work. The results show that no soil of this nature can be used indiscriminately like SAFL, without a discerning technological control for MCT Methodology tests is accomplished and that all the recommended executive procedures, in matter that they guarantee that the base doesn’t suffer “softening” for saturation effect, be assisted. In spite of, the employment of lateritic fine sandy soils constitutes an alternative technically viable for low cost paving in the Southern Coastal Plain of RS. / Na Planície Costeira do Sul do RS, as elevadas distâncias de transporte de materiais pétreos têm inviabilizado economicamente a pavimentação de vias caracterizadas pelo baixo volume de tráfego. Visando a redução destes custos, buscam-se alternativas para substituição dos materiais ditos nobres por solos locais no projeto e execução das estruturas de pavimentos. Nesta dissertação são apresentados resultados da investigação de propriedades físicas, mineralógicas e tecnológicas de solos arenosos finos de um agrupamento geotécnico denominado “areias lateríticas” por Bastos (2002). Estes solos, que constituem o horizonte subsuperficial de perfis de Argissolo Vermelho-Amarelo desenvolvido sobre a Barreira Litorânea BII pleistocênica, com características físicas e morfológicas similares aos solos arenosos finos lateríticos (SAFL) encontrados na região sudeste, foram submetidos ao critério de escolha de solos para bases pela Metodologia MCT (Villibor e Nogami, 1982). Nenhum dos solos pesquisados atende na totalidade o critério proposto. O solo ARMAR, embora apresente expansão acima do limite da especificação, é aquele que apresenta melhor desempenho quanto a capacidade de suporte, e é um dos solos que menos se afasta do limite superior indicado quanto a infiltrabilidade. Este fato, aliado ao mesmo pertencer a uma jazida comercial, motivou a utilização do mesmo no dimensionamento pelo Método da PMSP (PMSP, 1992) de uma hipotética estrutura de pavimento com base em SAFL realizado neste trabalho. Os resultados mostram que nenhum solo desta natureza pode ser indiscriminadamente utilizado como SAFL, sem que um criterioso controle tecnológico pelos ensaios da Metodologia MCT seja realizado e que todos os procedimentos executivos recomendados, em particular que garantam que a base não sofra “amolecimento” por efeito de saturação, sejam atendidos. Não obstante, o emprego de solos arenosos finos de comportamento laterítico constitui uma alternativa tecnicamente viável para pavimentação de baixo custo na Planície Costeira Sul.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2006. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-12-16T02:44:18Z No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-12-18T18:16:36Z (GMT) No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) / Made available in DSpace on 2013-12-18T18:16:36Z (GMT). No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) Previous issue date: 2006 / Este trabalho objetiva avaliar a estrutura e dinâmica da associação de macroinvertebrados bentônicos da zona entremarés de dois locais com distintas características ambientais da praia do Cassino, RS, Brasil. O local 1 possui características de praia dissipativa extrema, sedimentos finos e baixa hidrodinâmica, enquanto que o local 2 características dissipativas/intermediárias, sedimento mais grosseiros e maior hidrodinâmica. Eventos esporádicos de deposição de lama são observados no local 1. Foi realizado um acompanhamento durante 14 meses (abril/04 até maio/05) com amostragens mensais. Os 2 primeiros meses foram considerados como piloto, sendo seus dados abordados no capítulo III. Em cada local, foram demarcadas três transversais (separadas por 50m) perpendicular a linha d’água, nas quais amostras foram coletadas em triplicata em 4 níveis (separados por 10 m). As transversais se estenderam desde 10m acima do varrido superior, até cerca de 1m de profundidade. No capítulo I, foi considerada a variabilidade temporal da associação. Esta apresentou uma marcada dinâmica, sendo as principais variações ligadas às dinâmicas populacionais e perturbações físicas. Durante o inverno foram observadas baixas densidades, as quais foram relacionadas à ausência de recrutamentos, deposição de lama em abril e embancamentos de baixas intensidades. Na primavera ocorreu explosão populacional de Scolelepis gaucha, migração de adultos de Mesodesma mactroides do infralitoral para a zona entremarés e um evento de embancamento. Durante o verão foram observados recrutamentos de M. mactroides, Donax hanleyanus e Emerita brasiliensis. O outono foi caracterizado por baixas densidades, exceto pelo recrutamento de D. hanleyanus. O capítulo II abordou a distribuição perpendicular à linha d’água e paralela à linha d’água da fauna em diferentes escalas. O local 2 apresentou maior diversidade do que o local 1. A diversidade foi maior provavelmente devido a presença dos anfípodes Phoxocephalopsis sp. e Plastyschnopidae, os quais estiveram praticamente ausentes no local 1. Verificou-se que praias dissipativas/intermediárias podem suportar maior diversidade da macrofauna bentônica do que as dissipativas extremas, possivelmente, pela capacidade da associação macrozoobentônica de se beneficiar da maior hidrodinâmica na zona de varrido. As diversidades menores no local 1, podem ainda, ser atribuídas as perturbações causadas pelas deposições esporádicas de lama. Através de análises multivariadas foram identificadas 3 zonas: o mesolitoral médio, o superior do varrido e o inferior do varrido juntamente com a arrebentação interna. As espécies características de cada zona variaram com a estação do ano. Foram observadas densidades decrescentes do mesolitoral em direção ao infralitoral. Não foram evidentes padrões de distribuição paralela à linha d’água na escala de dezenas de metros, devido a grande homogeneidade sedimentar registrada nesta escala. No capítulo III foram analisados com maiores detalhes dois eventos: mortalidade pós deposição de lama em abril/04 e embancamento em outubro/05. A recomposição da fauna mostrou-se bastante rápida, em ambos eventos, registrou-se a mesma composição após 3 meses, entretanto as populações foram caracterizadas por organismos juvenis e recém assentados. Sendo que a manutenção de estoques adultos foi afetada. A deposição de lama ocasionou a mortalidade de toda a associação. O evento de embancamento afetou, principalmente, os juvenis+adultos do bivalvo M. mactroides. É provável que esses eventos sejam o principal fator estruturador de longo prazo das associações destes locais. / The present study aims to analyze the structure and dynamics of the intertidal macrobenthic assemblages in two sites with distinct environmental characteristics of Cassino beach, RS, Brazil. Site 1 can be characterized as an extreme dissipative beach, with fine sediments and low hydrodynamics and site 2 is a dissipative/intermediate beach, with coarser sands and high hydrodynamics. Sporadic muddy deposition events occur in site 1. Sampling was conduct monthly from april/2004 to may/2005. Data from the fist two months was considered as a pilot study and was included just in chapter III. In each site, three transect lines, spaced 50 m apart, were defined perpendicular to the shore line, samples were collect in triplicate in 4 levels (10 m apart). Each transect was extend from 10 above de swash limit to 1m deep in the inner surf zone. Chapter I aimed to describe the temporal variability of the intertidal assemblages. A striking dynamics was recognized through samplings times. The mains temporal changes were influenced by the population dynamics of numerically dominants species and physical disturbances. In winter was found a low density and diversity of the assemblages, with were related to absence of recruitments, an event of muddy deposition and stranding events of low effects. In spring was observed a population explosion of the polychaeta Scolelepis gaucha, migration of Mesodesma mactroides adults from the subtidal to the intertidal and a strand event. During summer was observed recruitments of tidal migrant species as M. mactoides, Donax hanleyanus and Emerita brasiliensis. Fall was characterized by low densities, except for an expressive recruitment of D. hanleyanus. Chapter 2 aimed to describe the spatial distribution across shore and along shore in distinct scales. Site 2 showed a higher diversity than site 1. The higher diversity were probably due the presence of amphipods Phoxocephalopsis sp. and Plastyschnopidae in site 2, which were absent in site 1. The results showed that dissipative/intermediate can support higher diversities than extreme dissipative conditions, probably because the assemblage can be beneficiated by the higher hydrodynamics of swash. The low diversities found in site 1, may be also related to sporadic muddy deposition events. The multivariate analyses showed three macrofaunal zones: mesolitoral; the higher swash; the lower swash together with the inner surf zone. The characteristics species of each zone varied according to the season. A decrease of density was verified from mesolitoral zone to the lower levels. No patterns were identified in a smaller scale (50m) of the along shore distribution, probably due the high homogeneity of the morpho-dynamics and sediments in this scale. In Chapter III, the period that occurred two mortality events were analyzed with more detail: muddy deposition in april/2004 and stranding in october/2004. The recuperation of the macrofauna assemblages was extremely fast, in three months they showed the same composition, although the populations were characterized by high densities of recruitments and juvenis. The adult stokes may be heavily impacted by this events. The muddy deposition caused a mortality of all population of the intertidal assemblages. The bivalve M. mactroides juvenis+adults was the organism most affected by the strand event. It’s likely that these events are the main long term factors structuring this assemblage.

The incessant growth of human populations, and the increase in recreational activities on seashores have altered the natural conditions of most coastal ecosystems, with a series of consequences for the distribution, abundance, and behavior of a range of organisms. While Atalaia beach in the city of Aracaju is highly urbanized, it is an important point in the migratory cycle of some species of migratory Nearctic shorebirds. The principal objective of the present study was to characterize the avian fauna of Atalaia beach, and to evaluate the influence of anthropogenic impacts on the spatial distribution and habitat use of migratory shorebirds. For this, a total of 81 surveys of a 5 km stretch of the beach were conducted on a monthly basis between October, 2008, and November, 2009. Data were also collected on the homogeneous availability organic matter of benthic macrofauna and the presence of beachgoers along the same stretch of shore. A total of 70 bird species were identified, of which the most abundant were the migratory shorebirds, with over 2500 individuals being recorded between October and March. The most common species were Arenaria interpres, Calidris alba, Calidris pusilla, and Charadrius semipalmatus, which together accounted for 79,09% of all birds recorded. These species were not distributed homogeneously across the survey area (H = 31.98; g.l. = 9; p = 0.002), nor did their abundance correlate with the availability of invertebrates (rs = 0.14; p = 0.71; n = 10). Unexpectedly, the sectors of the area with the highest concentrations of beachgoers also harbored the greatest abundance of birds (rs = 0.61; p = 0.059; n = 10). This appears to have been at least partly explained by the availability of leftover food within these areas, which represent an alternative dietary resource for the migratory shorebirds, and interferes in their behavior patterns. There is a clear need to better understand this phenomenon, and its potential consequences for the birds. / O contínuo crescimento das populações humanas, e o aumento das atividades recreativas ao longo do litoral alteram as condições naturais dos diversos ecossistemas costeiros, e consequentemente afetam a ocorrência, distribuição e comportamento de diversos organismos. Embora inserida no contexto urbano da cidade de Aracaju, a praia da Atalaia, apresenta-se como uma importante área no ciclo migratório de aves limícolas neárticas. O presente trabalho tem por principal objetivo trazer informações sobre a avifauna da praia da Atalaia, fazendo uma breve avaliação da influência antrópica sobre a distribuição espacial e uso de habitat das aves limícolas migratórias. Para isso, foram realizadas um total de 81 amostragens ao longo de 5 km de extensão de praia no período entre os meses de outubro de 2008 a novembro de 2009. Foram coletados dados sobre a homogeneidade espacial da macrofauna bêntica a partir da mensuração da matéria orgânica, bem como o número de pessoas foi contabilizado ao longo dessa faixa de praia. Foi identificado um total 70 espécies de aves, dentre estas as aves limícolas migratórias foram as mais abundantes, com registros de mais 2500 indivíduos entre os meses de outubro e março. As espécies mais comuns foram Arenaria interpres, Calidris alba, Calidris pusilla, e Charadrius semipalmatus que em conjunto totalizaram 79,09% do número total de indivíduos registrados. Essas espécies não apresentaram distribuição homogênea ao longo da faixa de praia amostrada (H = 31,98; g.l. = 9; p = 0,002), tampouco a abundância apresentou correlação os potenciais setores de disponibilidades de invertebrados (rs = 0,14; p = 0,71; n = 10). Inesperadamente, os setores de praia com maiores concentrações de pessoas também registraram as maiores abundâncias de aves (rs = 0,61; p = 0,059; n = 10). Tal fato parece estar associado com a oferta de restos de comidas e de lixo existentes nessas áreas, o que pode constituir um recurso alimentar alternativo para as aves migratórias, e consequentemente, influenciando os padrões de ocorrência e comportamentais dessas espécies. Faz-se necessário ampliar os estudos e pesquisas para um melhor entendimento dessa situação, e principalmente avaliar quais as potenciais consequências dessas substâncias para as aves e o ciclo migratório.

Plants established next to other plants may have their performance positively or negatively affected by their neighbors, which characterizes interactions of facilitation and competiton, respectively. Facilitation and competition, however, may occur simultaneously and understanding which one predominates in pairwise interactions under different ecological contexts is important to comprehend the structure of plant communities. According to the stress-gradient hypothesis (SGH), facilitation is expected to prevail in more severe environments, but the outcome of interactions may change depending on features of interacting individuals, such as life form and ontogenetic stages. As harsh conditions and high diversity of plant life-forms are characteristic of coastal dunes, the amount of studies about plant interactions has been rapidly increasing in these ecosystems, with apparent divergent conclusions. However, until now, there is not a systematic and quantitative synthesis about the factors affecting the net outcome of facilitation and competition in these ecosystems. We conducted a meta-analysis to investigate the effects of environmental stress and the simultaneous influence of plant life form and ontogenetic stage on the outcome of facilitation and competition in coastal dunes around the world. We used four performance measures to estimate the outcome of interactions: abundance, survival, growth, and reproduction. Contrary to what was expected by SGH, we found that negative impacts of neighbors on plant reproduction increase towards more arid conditions, but this effect was not observed for other performance measures. Our results also indicate that woody neighbors facilitate the survival of woody seedlings and the reproduction of herbs, while herbaceous neighbors facilitate the growth of other herbaceous plants. Overall, the outcome of plant interactions in coastal dunes depends on the performance variable measured and on both environmental conditions and plant features, indicating an interaction between these factors. Such interaction and different mechanisms underlying facilitation and competition should be more investigated in the future. The global scale of our meta-analysis supports generalization of important processes of succession and conservation in coastal dunes. Benefits of woody neighbors to the survival of woody seedlings corroborate the concept of successional feedbacks in the beach-inland physiognomic gradient, and our results reinforce the use of nurse plants in coastal dunes as a valuable tool to restoration of these endangered ecoystems / Plantas estabelecidas nas proximidades de outras plantas podem ter sua performance afetada positiva ou negativamente por seus vizinhos, caracterizando, respectivamente, interações de facilitação e competição. Considerando que ambas as interações podem ocorrer de forma simultânea, compreender o predomínio de cada uma delas em diferentes contextos ecológicos é fundamental para o entendimento da estrutura de comunidades vegetais. De acordo com a hipótese do gradiente de estresse (HGE), a facilitação tende a predominar em ambientes mais severos, mas o balanço das interações depende ainda das características dos indivíduos envolvidos, como forma de vida e estágio ontogenético. Como condições ambientais severas e alta diversidade de formas de vida vegetais são características de planícies costeiras, o número de estudos investigando interações entre plantas tem aumentado rapidamente nesses ambientes, com conclusões aparentemente divergentes. No entanto, ainda não há uma síntese sistemática e quantitativa dos fatores que afetam o balanço entre facilitação e competição nesses ecossistemas. Nós realizamos uma meta-análise em escala global para investigar os efeitos do estresse ambiental e a influência simultânea da forma de vida e do estágio ontogenético das plantas sobre o balanço entre facilitação e competição em planícies costeiras. Utilizamos quatro variáveis de performance para estimar o balanço de interações: abundância, sobrevivência, crescimento e reprodução. Ao contrário do predito pela HGE, encontramos que impactos negativos de plantas vizinhas sobre a reprodução de outras plantas aumentam com a aridez do ambiente, mas que esse efeito não é observado para outras variáveis de performance. Nossos resultados também mostram que vizinhos lenhosos facilitam a sobrevivência de plântulas lenhosas e a reprodução de plantas herbáceas, enquanto vizinhos herbáceos facilitam o crescimento de outras herbáceas. De modo geral, o balanço das interações depende da variável de performance medida e tanto de condições ambientais quanto de características das plantas, indicando que esses fatores interagem. Tal interação e os diferentes mecanismos subjacentes à facilitação e à competição devem ser melhor investigados no futuro. A maior sobrevivência de plântulas lenhosas na presença de vizinhos lenhosos corrobora a ideia de retroalimentação positiva no processo sucessional que caracteriza o gradiente fisionômico da praia ao interior. Nossos resultados também reforçam o potencial do uso de plantas-berçários como ferramenta para restauração de planícies costeiras degradadas

The soil strata is often subjected to various kinds of vibrations such as that caused by earthquakes, water waves, traffic loads, wind power plants, construction related equipments, pile driving and vibratory machines. The strains induced in a soil mass due to the vibrations generated by these different sources often lie in a range of 0.0001% - 0.1%. The estimation of the shear modulus (G) and damping (D) of soils in this strain range becomes an important aspect for performing the analysis and design of various geotechnical structures subjected to different kinds of vibrations. Strain amplitude, effective confining stress, void ratio/relative density, number of vibration cycles and cyclic strain history are some of the key parameters that influence the modulus and damping characteristics of sands. Although, the effects of strain amplitude, confining pressure and relative density have been studied quite extensively in literature, only limited studies seem to have been reported in literature to examine the effects of the cyclic strain history and the vibration cycles on these dynamic properties. The objective of this thesis is to study the effects of the cyclic strain history and the number of vibration cycles on the shear modulus and damping ratio of dry sands in a strain range of 0.0001% to 0.1%. A number of resonant column tests have been performed on dry sand specimens to examine the effect of the cyclic shear strain history, by including both increasing and decreasing strain paths, on the shear modulus and damping ratio for different combinations of relative densities (Dr) and confining pressures (σ3); an increasing strain path intends to simulate a situation when a vibratory machine is just started before reaching a steady state of vibration, and on the other hand, the decreasing strain path matches a condition when the machine is shut down after running continuously in a steady state for some time. The specimen has been subjected to a series of cycles of increasing and decreasing shear strain paths approximately in a shear strain range of 0.0006% - 0.1%. For chosen values of relative density and confining pressure, two different series of tests beginning with either (i) an increasing strain path or (ii) a decreasing strain path, were performed. In addition, the influence of the numbers of the vibration cycles which are used to measure the resonant frequency of the specimen, referred to as the cycle constant, on the values of shear modulus has also been analyzed. Irrespective of the strain path adopted to commence the test or the cycle constant used to perform a resonant column test, for a given strain amplitude, the shear modulus along the increasing strain path has been found to be always greater than the corresponding modulus value along the decreasing strain path. For the series of tests which were commenced with the increasing strain path, the shear modulus corresponding to the first increasing strain path becomes always the highest as compared to the subsequent strain paths. For a given strain cycle, irrespective of relative density of sand, the difference between the values of G associated with the increasing and decreasing strain paths becomes always the maximum corresponding to a certain shear strain level. The maximum reduction in the shear modulus, due to the cyclic variation of the shear strain, was noted to be approximately one fourth of the maximum shear modulus (G0). This reduction in the shear modulus, on account of the cyclic variation of the shear strain, increases generally with decrease in the values of both relative density and confining pressure. The damping ratio for a given shear strain for the increasing strain path was noted to be lower than the corresponding value for the decreasing strain path except for the first increasing strain path. For a particular strain level, the series of tests started with the decreasing strain path resulted in a lower value of shear modulus for all the cyclic strain paths as compared to the tests which were commenced with the increasing strain path. The modulus reduction curve for the first increasing strain path was noted to be more or less the same irrespective of the value of the chosen cycle constant. For the subsequent strain paths, an increment in the cycle constant value caused a reduction in the shear modulus at a particular shear strain level. In order to match a situation when the machine is running continuously in a steady state of vibration, resonant column tests were conducted in a torsional mode by inducing a large number of the vibration cycles with the shear strain amplitude in a range of 0.0005%-0.05%. Corresponding to a given input voltage of the drive mechanism, the specimens were subjected to a number of vibration cycles ranging from 1,000 to 50,000. The values of shear modulus and damping ratio, before and after the application of vibration cycles, were determined for several input voltages ranging from 0.001 V (minimum) to 0.3 V (maximum). The tests were carried out for different combinations of relative densities and confining pressures. For the chosen relative densities, hardly any influence of vibration cycles on the values of G and D were noted for the strain amplitude below the threshold strain level (0.0024% - 0.0044%). Beyond the threshold strain level, an induction of the vibration cycles leads to a continuous increment in the shear strain which eventually causes (i) a decrease in the shear modulus, and (ii) an increase in the damping ratio. This effect was found to become especially more significant for lower values of relative densities as well as confining pressures. The percentage changes in the values of (i) shear strain, (ii) shear modulus, and (iii) damping ratios after the introduction of vibration cycles were noted to increase with an increment in the number of vibration cycles. However, for a given increment of the vibration cycles, the changes in the values of shear modulus and damping ratio were generally noted to subside with an increase in the number of the vibration cycles. At various strain levels, the magnitude of the shear modulus was observed to increase continuously with an increase in the values of both relative density and confining pressure. For the shear strain greater than the threshold strain (0.0024% - 0.0044%), a reduction in the damping ratio values was also noted with an increase in the magnitudes of the confining pressure. On the other hand, the influence of relative density on the damping ratio was found to be relatively negligible. The shear modulus reduction curves from the present tests' data were found to compare reasonably well with the empirical curves proposed in the literature, especially for low values of the confining pressure. A deviation of the present modulus reduction curves from the empirical curves was observed generally at large shearing strains. However, the damping values obtained from the present study were noted to be lower than the values predicted by the existing empirical correlations, particularly for low values of the confining pressure. An attempt has also been made to improve the accuracy of the measurement of the arrival times of both primary (P) waves and shear (S) waves while conducting bender/extender element tests. For this purpose, a series of laboratory tests were performed on dry sand at different frequencies, varying between 1 kHz and 10 kHz, for medium dense and very dense sands with different values of the confining pressures. While determining the times of arrival of both P and S waves, two corrections have been proposed to incorporate (i) the presence of an initial offset in the input signal, and (ii) the time lag due to an existence of peripheral electronics between the input and received signals when the source and receiver elements are kept in direct contact with each other. The absolute magnitude of the resultant of these two corrections was found to reduce with an increase in the frequency of the input signal. The determination of the P-wave arrival time does not pose much difficulty. It has been noted that it becomes equally accurate to measure the arrival times of the S-wave provided the proposed corrections are incorporated. The maximum shear modulus values measured from the resonant column tests and the bender element tests by incorporating these two corrections were found to compare reasonably well with each other. The thesis brings out the effects of the cyclic strain history and the vibration cycles on the shear modulus and damping ratio of dry sand. The results obtained are expected to be useful while doing the analysis and design of geotechnical structures subjected to different kinds of vibrations.

Un problema frecuente en la construcción de viviendas en el cono sur de Lima es el proceso constructivo de la cimentación. Al ser suelos en su mayoría arenosos y al excavar los cimientos en este tipo de suelo, se evidencia un peligro de deslizamiento del talud y, por consiguiente, un riesgo para la vida de los trabajadores. Ello se agrava con mayor intensidad cuando los trabajadores de estas obras no tienen los conocimientos técnicos necesarios para realizar una buena práctica constructiva en cimentaciones. La presente tesis tiene como objetivo contribuir a que estas construcciones tengan una adecuada cimentación de forma segura para todos, por lo que se condujo un estudio de zonificación geotécnica y se obtuvieron los tipos de suelo preponderantes en el distrito. El análisis se realizó en el distrito de Villa María del Triunfo, para lo cual se ejecutaron más de 500 calicatas, se realizaron los respectivos ensayos de laboratorio, se elaboró para cada calicata un perfil estratigráfico, se zonificó todo el distrito, se analizaron los tipos de suelos predominantes, y se ejecutaron los estudios pertinentes de estabilidad de taludes, para, finalmente, calcular las profundidades de cimentación de las tablestacas que puedan soportar excavaciones de hasta dos metros de profundidad. Por último, se concluye que la tablestaca de madera logra asegurar la estabilidad de los taludes en las excavaciones de hasta dos metros de profundidad en los tres tipos de arenas preponderantes en el distrito de VMT. / A frequent problem that arises when building homes in Lima’s Cono Sur is the process of building foundations. As the soils are mostly sandy and as this type of soil is excavated for the foundations, the risk of slope failure becomes evident, and consequently, so does the risk at which the workers’ lives are. This is more intensely aggravated when the workers at these worksites do not have the necessary technical knowledge to execute a good foundation-building process. The objective of this thesis is to help these constructions have adequate foundations safely for everyone, thus a geotechnical zoning study was conducted and the predominant types of soils in the district were obtained. The analysis was carried out in the Villa María del Triunfo district, hence over 500 trial pits were dug, respective laboratory tests were performed, a stratigraphic profile for each trial pit was developed, the entire district was zoned, the predominant types of soils were analyzed, and corresponding slope stability studies were undertaken, in order to, in the end, calculate the sheet pile foundation depths that can support excavations up to two meters deep. Finally, the conclusion shows that wood sheet piles managed to ensure slope stability in excavations up to two meters deep in the three different types of sand that are predominant in the VMT district. / Tesis

MSc (Botany) / Department of Botany / See the attached abstract below

En la actualidad, dentro del ámbito nacional, la succión matricial es un parámetro que no se toma en cuenta dentro de los estudios de mecánica de suelos. Este motivo junto con la constante amenaza de deslizamientos de masa en el país generó la necesidad de llevar acabo un análisis para verificar los efectos del parámetro de succión dentro de un análisis de estabilidad de taludes de manera específica en tres sectores de la carretera Lima – Canta – Huayllay, Región Lima; y confirmar si los estudios sobre su relación con la resistencia al corte siguen el mismo principio. En el presente trabajo se realizan tres exploraciones geotécnicas directas (calicatas) dentro de la carretera en mención para la recuperación de muestras de suelo, realizar las respectivas caracterizaciones físicas y mecánicas como también efectuar un análisis de estabilidad de taludes para cada sector estudiado. Para la obtención de la succión matricial se utilizan curvas características suelo - agua para cada tipo de suelo muestreado; asimismo, se utiliza el software SLIDE para el análisis de estabilidad de talud estático y pseudoestático. / Nowadays, within the national scope, the matrix suction parameter is not taken into consideration within the soil mechanics studies. This reason, in conjunction with the constant threat of mass landslides in the country, generated the need to carry out an analysis to verify the effects of matrix suction within a slope stability analysis specifically in three sectors of the Lima - Canta highway. - Huayllay, Lima Region; and confirm whether studies on its relationship with shear strength follow the same principle. In the present work, three direct geotechnical explorations (pits) are performed within the mentioned road for the recovery of soil samples, to conduct the respective physical and mechanical characterizations as well as to conclude with a slope stability analysis for each studied sector. To obtain the matrix suction, soil-water characteristic curves were used for each type of soil sampled; likewise, SLIDE software is used for static and pseudostatic slope stability analysis. / Trabajo de investigación

Pile foundations near the crest of a slope are often required to resist lateral loads. This is particularly important for piles at the abutments of bridges. However, limited full-scale test data are available to indicate how the lateral resistance of a pile would be affected when it is located near the crest of a slope. To investigate the effect of a slope on lateral pile resistance, three full scale lateral load tests were conducted on an instrumented steel pipe pile. For the first test, the pile was laterally loaded in horizontal ground. For the second test the pile was at the crest of a 30 degree slope and in the third test the pile was placed three diameters behind the crest of the 30 degree slope. The soil around the pile consisted of clean sand compacted to about 95% of the modified Proctor maximum unit weight for all three tests. Laboratory and in-situ direct shear tests indicated that the friction angle of the sand was approximately 39 degrees. The pile was instrumented with strain gages at approximately 1.5 ft intervals along its length so that the bending moment versus depth profile could be determined. Pile head load, deflection, and rotation were also measured. Based on the results, the presence of the slope decreased the ultimate lateral resistance of the pile-soil system by approximately 25% and 10% for tests two and three, respectively. The presence of the slope also resulted in an increase in the maximum bending moment of approximately 40% and 30% for tests two and three, respectively. Analyses using LPILE matched the lateral resistance for the pile in horizontal ground, but significantly overestimated the decrease in resistance due to the sloping ground. A mathematical model was developed to predict the ultimate strength of a pile located some distance from the crest of a cohesionless sloping profile. Parametric test results using the model were within 2.6 % of the measured results of tests two and three.

During 1967-68 experiments to determine the comparative effect of various nitrogenous fertilizers on soil reaction and soil aggregation of the Fox sandy loam, the Lincoln loam and the Lincoln clay loam were carried out in the pedology Laboratory of the Department of Geography, McMaster University. The soil samples were taken from the Horticultural Experiment Station, Simcoe, Ontario. A review of literature is presented in Chapter II. Chapter III discusses experimental techniques, results and a discussion of problems encountered. Chapter IV summarizes the results of the survey and analyses. / Thesis / Master of Arts (MA)