Los suelos arcillosos tienen la característica de hincharse cuando son expuestos a la humedad y de contraerse cuando existe sequedad, esto representa un problema especialmente en las cimentaciones que se construyen sobre este tipo de suelo. Por ello, la presente investigación tiene como finalidad evaluar el efecto en las propiedades mecánicas al adicionar vidrio y valvas de molusco triturados a este suelo problemático. La presente tesis tuvo un enfoque cuantitativo, ya que el estudio del suelo arcilloso se realizó mediante la medición de indicadores tales como Corte directo, Proctor Modificado, Límites de Atterberg y Granulometría. Además, el uso del vidrio y valvas de molusco disminuirá los costos de mejoramiento del suelo arcilloso, ya que son materiales que se encuentran por abundancia en la zona de estudio. Y los costos para adquirir estos productos son mínimos. Con esta clase de mejora presentada en la investigación, el suelo arcilloso mejora notablemente, ya que este aumenta su capacidad de soporte. Los resultados muestran que el uso de las valvas de molusco y polvo de vidrio brindan un aumento de la resistencia del suelo arcilloso, además muestra una disminución de las deformaciones transversales que están presentes por la aplicación de cargas sobre el terreno arcilloso. Finalmente, se observó que, al combinar el suelo arcilloso con el polvo de valvas de molusco y polvo de vidrio, esta mezcla disminuye la absorción de agua, convirtiendo de esta manera más estable al terreno arcilloso. / Clayey soils have the characteristic of swelling when exposed to moisture and shrinking when there is dryness, this represents a problem especially in foundations that are built on this type of soil. Therefore, the purpose of this research is to evaluate the effect on mechanical properties by adding glass powder and mollusk shell powder to this problem soil. The present thesis had a quantitative focus, since the study of clay soil was carried out by measuring indicators such as Direct Cut, Modified Proctor, Atterberg Limits and Granulometry. In addition, the use of glass powder and mollusk shells will decrease the costs of clay soil improvement, since they are materials found in abundance in the study area. And the costs to purchase these products are minimal. With this kind of improvement presented in research, clayey soil improves markedly as it increases its bearing capacity. The results show that the use of mollusk shells and glass powder provide an increase in the resistance of the clay soil, in addition it shows a decrease in the transverse deformations that are present by the application of loads on the clay soil. Finally, it was observed that, when combining clay soil with shellfish powder and glass powder, this mixture decreases the absorption of water, thus making clay soil more stable. / Tesis

El presente documento presenta un estudio basado en el análisis del comportamiento de las propiedades mecánicas de un suelo limo arcilloso con la incorporación de fibras de PET triturado. Para conocer el comportamiento de un suelo, es necesario conocer primero su génesis. Las muestras analizadas provienen de la capa de subrasante de una carretera que une las ciudades de Munichis y Yurimaguas, en el departamento de Loreto, Perú. El tipo de suelo en las zonas de selva baja suele tener características como bajo índice de soporte, media a elevada plasticidad, y demás características que lo hacen considerar como un suelo problemático, esto debido a factores como el clima, humedad, y ubicación geográfica. Para realizar un análisis preciso del comportamiento de este suelo en combinación con el PET, se llevó a cabo ensayos como la prueba del hidrómetro, Proctor modificado y CBR con porcentajes variables de PET respecto a la masa de la muestra de suelo. Cada uno de ellos, principalmente, para conocer bien el tipo de muestra, y el índice de soporte con cada porcentaje incorporado. Los resultados son evidencia que mientras mayor sea el porcentaje de PET, el suelo pierde características resistentes, por lo que su índice de soporte disminuye; por el contrario, mientras menor es el porcentaje de PET incorporado, el índice de soporte se incrementa. En suma, para poder conocer el comportamiento esperado, es necesario realizar distintas pruebas, y haciendo uso de distintos tipos de suelos. / This study is based on the analysis of the behavior of the mechanical properties of a silty clay soil with crushed PET fibers incorporated. To understand the behavior of a soil, it is necessary to know its origin. The analyzed samples come from the subgrade layer of a highway that connects the cities of Munichis and Yurimaguas, in the region of Loreto, Peru. The material in this area usually has characteristics such as low support index, medium to high plasticity, and other characteristics that make it considered a problematic soil, this due to factors such as climate, humidity, and geographical location. To perform a precise analysis of the behavior of this soil in combination with PET, tests such as the hydrometer test, Modified Proctor and CBR with different percentages of PET, were carried out. to the mass of the sample. Each of them mainly to know well the type of sample, and the support index with each percentage incorporated. The results show that as higher the percentage of PET, the soil loses resistant characteristics, so its support index decrease, on the other hand, the lower percentage of PET used, the support index increases. In summary, to know the expected behavior, it is necessary to carry out different tests, and make use of different types of soil. / Trabajo de investigación

A major instrumented geosynthetic reinforced approach embankment was constructed to 5.5 m elevation above ground, with prefabricated vertical drains, over a soft compressible clay deposit at Leneghan, Newcastle, Australia in May 1995. The field monitoring of settlements for over six years shows that the embankment manifests significant creep. The instrumentation, field performance and the finite element analyses for predicting the long-term performance of this embankment are described in this thesis. The maximum settlement of 1.1 m was observed one year after the completion of construction. However, the embankment continued to settle at a rate of 0.4 mm/day for the next 5 years. The horizontal displacements of 0.09-0.14 m at various locations and the maximum reinforcement strains of 0.67% were recorded. A numerical model was developed to perform a fully coupled large deformation elasto-viscoplastic finite element analysis for this performance prediction based on creep model proposed by Kutter and Sathialingam (1992). The foundation soil was modelled with creep material behaviour using six noded linear strain triangular elements. A well-documented case history ??? Sackville embankment, New Brunswick, Canada was analysed using this model as a benchmark problem and the model was found to predict all the behaviour characteristics reasonably well. The results obtained from finite element analysis using this model are shown to be in reasonable agreement with the observed performance of Leneghans embankment in terms of settlements, horizontal displacements, excess pore pressures and geosynthetic strains. But, the prediction of settlements was less than satisfactory beyond April 1999. Finite element analyses were performed to study the sensitivity of this embankment behaviour on the variation of hydraulic conductivity values and geosynthetic reinforcement properties. This sensitivity study indicated that the kv variation, the kh/kv ratio and the nominal values of geosynthetic properties adopted in the benchmark analysis are reasonable enough for the long-term behaviour prediction.

A major instrumented geosynthetic reinforced approach embankment was constructed to 5.5 m elevation above ground, with prefabricated vertical drains, over a soft compressible clay deposit at Leneghan, Newcastle, Australia in May 1995. The field monitoring of settlements for over six years shows that the embankment manifests significant creep. The instrumentation, field performance and the finite element analyses for predicting the long-term performance of this embankment are described in this thesis. The maximum settlement of 1.1 m was observed one year after the completion of construction. However, the embankment continued to settle at a rate of 0.4 mm/day for the next 5 years. The horizontal displacements of 0.09-0.14 m at various locations and the maximum reinforcement strains of 0.67% were recorded. A numerical model was developed to perform a fully coupled large deformation elasto-viscoplastic finite element analysis for this performance prediction based on creep model proposed by Kutter and Sathialingam (1992). The foundation soil was modelled with creep material behaviour using six noded linear strain triangular elements. A well-documented case history ??? Sackville embankment, New Brunswick, Canada was analysed using this model as a benchmark problem and the model was found to predict all the behaviour characteristics reasonably well. The results obtained from finite element analysis using this model are shown to be in reasonable agreement with the observed performance of Leneghans embankment in terms of settlements, horizontal displacements, excess pore pressures and geosynthetic strains. But, the prediction of settlements was less than satisfactory beyond April 1999. Finite element analyses were performed to study the sensitivity of this embankment behaviour on the variation of hydraulic conductivity values and geosynthetic reinforcement properties. This sensitivity study indicated that the kv variation, the kh/kv ratio and the nominal values of geosynthetic properties adopted in the benchmark analysis are reasonable enough for the long-term behaviour prediction.

Made available in DSpace on 2016-06-02T18:55:25Z (GMT). No. of bitstreams: 1 5511.pdf: 2599915 bytes, checksum: c246a5f7092e814f87e383c45b31d9f2 (MD5) Previous issue date: 2013-09-06 / Financiadora de Estudos e Projetos / Can vinasse accelerate the change of minerals in rock powder for obtaining fertilizer, with utilization of residues from alcohol agro and mining industries? Answering this question was the main objective of this study. So, it was carried out two experiments in a laboratory in a completely randomized set using PVC columns in which we reproduced the 0-50 cm layers of a very clayey Red Oxisol and a Quartzipsamment. In the first test, with duration of 30 days, it was evaluated the application form of the mixture into the soil. It were tested incorporation of basalt powder previously in soil and incubation of basalt powder and vinasse in the laboratory for 24 hours and then applied to the soil. In Red Oxisol were used two doses of basalt powder (0 and 2,0 t ha-1), a dose of vinasse (200 m3 ha-1) and as a control, a dose of water (200 m3 ha-1) using the same amounts of rock powder. For this test, samples were collected from the surface of the columns in 1, 7, 15 and 30 days of experiment. In the second test, with duration of 90 days, using the two soils, were added three doses of basalt powder (0, 2,0 and 4,0 t ha-1) and a dose of vinasse (200 m3 ha-1). The control was made by treatments with water (200 m3 ha-1) with the same doses of rock powder. Samples were collected on the surface of each column in 1, 15, 30, 45, 60 and 90 days and at the end of the experiment, in botton and in the leachate. For the surface samples in the first and second tests and the botton in the second test, we determined the levels of macronutrients (P, K, Ca, Mg, S), micronutrients (B, Fe, Cu, Mn, Zn), H + Al, Al, organic matter, pH in CaCl2, sum of bases, base saturation and cation exchange capacity. In the leachate were determined Ca, Mg, K, SO4, Fe, Mn and Zn. In the first test, the evaluation of the application form of the mixture indicated that there was no difference between the use of basalt powder and vinasse incubated for 24 hours or previously incorporation of rock powder in the soil and then application of vinasse. In the second test, there were significant effects of solvent and soil in the surface layer, with variations in the levels of the attributes analyzed over time. The dose of basalt powder was not significant for most attributes analyzed, except for the levels of boron and iron. On balance levels at the beginning and end of the experiment, the results suggest that sorption phenomena with neoformed mineral phases or organic acids may have occurred. The mixture of vinasse and rock powder is an alternative fertilizer and reduces the consumption of soluble fertilizers, but further studies are needed to evaluate the sorption phenomena and availability of cations in the mixture. / Vinhaça pode acelerar a alteração de minerais em pó de rocha para obtenção de fertilizantes, com aproveitamento de resíduos de agroindústrias de álcool e de mineradoras? Responder a esta pergunta foi o principal objetivo deste estudo. Assim, foi montado em laboratório dois ensaios inteiramente casualizados em colunas de PVC nas quais foram reproduzidas as camadas 0-50 cm de um Latossolo Vermelho muito argiloso e de um Neossolo Quartzarênico. No primeiro ensaio, com duração de 30 dias, foi avaliado o modo de aplicação da mistura no solo. Foram testados a incorporação de pó de basalto previamente no solo e a incubação de pó de basalto e vinhaça em laboratório por 24 horas e depois aplicação no solo. Em Latossolo, foram utilizadas duas doses de pó de basalto (0 e 2,0 t ha-1), uma dose de vinhaça (200 m3 ha-1) e como controle uma dose de água (200 m3 ha-1) com as mesmas quantidades de pó de rocha. Para este ensaio foram coletadas amostras da camada superficial das colunas aos 1, 7, 15 e 30 dias de experimento. No segundo ensaio, com duração de 90 dias, utilizando os dois solos, foram adicionadas três doses de pó de basalto (0; 2,0 e 4,0 t ha-1) e uma dose de vinhaça (200 m3 ha-1). O controle foi feito por meio de tratamentos com água (200 m3 ha-1) e com as mesmas doses de pó de rocha. Foram coletadas amostras na superfície de cada coluna aos 1, 15, 30, 45, 60 e 90 dias e, ao final do experimento, em profundidade e no lixiviado. Para as amostra em superfície do primeiro e segundo ensaios e em profundidade do segundo ensaio, foram determinados os teores de macronutrientes (P, K, Ca, Mg, S), micronutrientes (B, Fe, Cu, Mn, Zn), H+Al, Al, matéria orgânica, pH em CaCl2, soma de bases, saturação por bases e capacidade de troca catiônica. No lixiviado foram determinados os teores de Ca, Mg, K, SO4, Fe, Mn e Zn. No primeiro ensaio, a avaliação do modo de aplicação da mistura indicou que não houve diferença entre a utilização do pó de basalto incubado em vinhaça por 24 horas ou incorporação do pó de rocha no solo e em seguida aplicação de vinhaça. Já no segundo ensaio, houve efeito significativo do solvente e do solo na camada superficial, com variações nos teores dos atributos analisados durante o tempo. A dose de pó de basalto não foi significativa para a maioria dos atributos analisados, com exceção dos teores de boro e de ferro. No balanço de teores no início e no fim do experimento, os resultados sugerem que fenômenos de sorção com fases minerais neoformadas ou com ácidos orgânicos podem ter ocorrido. A mistura de vinhaça e pó de rocha é uma alternativa de adubação e permite reduzir o consumo de fertilizantes solúveis, mas são necessários estudos complementares para avaliar fenômenos de sorção e de disponibilização de cátions nessa mistura.

Pericopsis elata is an African forestry species commercialized under the vernacular names afrormosia or assamela. It is one of the principal species commonly exploited for timber in the Democratic Republic of Congo (DRC) and in a lesser extent in Cameroon and Congo. In view of its sustainable resource exploitation, the species is in centre of numerous polemics notably in the European Union. It is one of the rare commercialized species that produce wood, since 1992, as listed in the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) annex II specifying that “the exploitation of afrormosia necessitate the deliverance and a prior presentation of exploitation permit”. The most important reserves of afrormosia are found in DRC. This doctoral thesis presents the ecology of this particular tree and its behaviour regarding forestry exploitation. It allows to inform the international organisms such as CITES as well as the national policy-makers on the vulnerability of afrormosia and to propose appropriate measures that can avoid future unsustainable/unregulated exploitation activities/Pericopsis elata est une espèce forestière africaine commercialisée sous les noms d’afrormosia ou d’assamela. Elle est une des principales espèces exploitées pour le bois d’œuvre en République Démocratique du Congo (RDC) et dans une moindre mesure au Cameroun et au Congo. Elle est au centre de nombreuses polémiques, notamment dans l’Union européenne, en ce qui concerne la durabilité de son exploitation. C’est une des rares espèces commerciales productrice de bois d’œuvre listée, depuis 1992, dans l’Annexe II de la CITES (Convention sur le commerce international des espèces en danger d’extinction) qui spécifie que « L'exportation d'un spécimen d'une espèce inscrite à l'Annexe II nécessite la délivrance et la présentation préalables d'un permis d'exportation ». Les plus grandes réserves d’afrormosia se trouvent en RDC. Cette thèse de doctorat porte sur l’écologie de cet arbre et sur son comportement vis-à-vis de l’exploitation forestière. Elle permet d’informer les organismes internationaux comme la CITES et les décideurs nationaux sur la vulnérabilité de l’afrormosia et de proposer des mesures à prendre pour que l’espèce ne soit pas menacée par une exploitation mal conduite et non régulée / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

MENVSC / Department of Ecology and Resource Management / Some boreholes in South Africa which serve as a source of drinking water for rural communities are reported to have high fluoride concentration, much above the WHO guideline of 1.5 mg/L. This study aimed at activating aluminosilicate clay soil mechanochemically, modifying aluminosilicate clay soil with Al-oxide and fabricating porous ceramic granules using Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch and evaluating their performances in defluoridation of groundwater. The raw clay materials were mechanochemically activated for 5, 10, 15 and 30 minutes for physicochemical transformation of the solid aggregate. The morphology of the samples showed the honeycomb structure. The surface area analyses of samples using Brunauer–Emmett–Teller (BET) gave the highest surface area of 50.5228 m2/g at 30 min activation time. Hence, the optimum activation time was 30 min. The Fourier Transform Infrared (FT-IR) analysis showed increase in the absorbance of FT-IR by Si-O-H groups at 510 cm-1 with increasing milling time. This is evidence that more surface Si-O-H groups were available at higher particle surface area that would be necessary to interact with fluoride. X-ray diffraction (XRD) analyses revealed that, at 30 minutes milling time, the peak broadening is intensified whereas the reflection peak intensities decreased. The X-ray fluorescence spectrometry (XRF) results for 30 minutes milling time showed that silica and alumina were the highest components in the clay soil. Using the activated clay in batch defluoridation of fluoride-spiked water, a maximum fluoride removal of 41% was achieved at a pHe of 2.41. The initial fluoride concentration was 9 mg/L while the sorbent dosage was 0.6 g/100 mL and the contact time being 30 minutes. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Optimization of Al3+ concentration for modification was carried out by modifying the mechanochemical activated aluminosilicate clay soil with different concentrations of Al3+ from which the optimum modification was achieved with 1.5 M. Characterisation studies on the Al-oxide modified mechanochemically activated aluminosilicate clay soil by SEM, BET, FT-IR, XRD and XRF, analyses were carried out to determine the resultant changes in physicochemical properties of the adsorbent owing to modification. The SEM image of Al-oxide modified mechanochemically activated clay soil showed many small pores and honey-comb structure on the surface of different images. The BET surface area and the BDH adsorption cumulative area of the Al-oxide modified mechanochemically activated v aluminosilicate clay soil were more than double those for the raw clay soil. There was also an increase in pore volume of the Al-oxide modified mechanochemically activated aluminosilicate clay soil. The FT-IR spectra showed that there was increase in the absorbance by the Si-OH, H-O-H, Al-O-H and Si-O-Al. The equilibrium pH of solution was higher than the point-of-zero charge (pHpzc) implying that fluoride removal occurred at solution pH > pHpzc where the net surface charge of the mechanochemically activated clay aluminosilicate soil was negative.The efficiency of 1.5 M Al-oxide modified aluminosilicate clay soil to remove fluoride from water was studied and found to be 96.5 % at pHe 6.86, contact time of 30 minutes and dosage of 0.3 g/100 mL for 10 mg/L fluoride solution at 200 rpm shaking speed. The result shows that Al-oxide modified mechanochemically activated aluminosilicate clay soil is effective for defluoridation. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Al-oxide modified mechanochemically activated aluminosilicate clay soil was tested for fluoride removal on field water and the percentage fluoride removal was 96.5 % at the dosage of 0.6 g/100 mL with the pHe of 6.48. The optimum Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch mixing ratio for fabrication of porous ceramic granules was determined by varying ratios and temperature. The optimum ratio found was 20:5:1.The porous ceramic granules were characterised using SEM, BET, FT-IR, XRD and XRF. SEM analysis showed that the porous ceramic granules have the porous structure of the organic foam template. The porous ceramic granule showed an increase in pore surface area and volume as compared to mechanochemically activated aluminosilicate clay soil. The FT-IR showed the presence of a strong broad bending and stretching vibrations band at about 993 cm-1 which shows the presence of Si–O–Si bonds. Mineralogical characterisation showed the presence of quartz, albite, horneblende and microcline as the main minerals of the calcined porous ceramic granules. The major oxides of the porous ceramic granules as shown by XRF analysis were SiO2, Al2O3, MnO and Na2O. The porous ceramic granules reduced the concentrations of fluoride in the water from 10 to 3.31 mg/L. The optimum adsorption capacity was 0.6648 mg/g at a pHe of 6.32 and the percentage fluoride removal was 66.9 % at an adsorbent dosage of 1.0063 g/100 mL and a temperature of 600 ⁰C. The porous ceramic granules were tested for fluoride removal on field water and the percentage fluoride removal was 45.4 % at the dosage of 1.0009 g/100 mL with the pHe of 7.87. Mechanochemically activated aluminosilicate clay soil showed higher adsorption capacity at acidic pH, therefore it is recommended that future work should focus on improving their adsorption capacity at wider range of pH. The porous ceramic granules can also be evaluated in column dynamic flow experiments.

MSc (Botany) / Department of Botany / The use of disturbance in the management of Savanna is a common rangeland practice in South Africa. A two-season trial was established in June 2016 and December 2016 to evaluate the effects of disturbance of different intensities on wetland belts in the Nylsvley Nature Reserve. The disturbances were in three different belts of different grass types at different intensities. The experimental treatments consisted of two different intensities, namely; high (H) and low (L). The Cyperus amabilis belt was regarded as site 1, the Sporobolus africanus as site 2, and the Themeda triandra as site 3. Seventeen kites were contracted in each belt, two times 1 m × 1 m at high and low intensity, followed by two times 2 m × 2 m one at high intensity. The results showed that disturbance affects the topsoil by removing the soil which is rich in nutrients producing pioneer species for the first few months and then original species were seen inhibiting again. / NRF