Geomembranes are one of the most widely used geosynthetics in various civil engineering applications. Their primary function is as a barrier to liquid or vapour flow. Smooth Geomembranes are frequently used in combination with different soils, and due to their low surface roughness, are challenging to design to ensure adequate shear strength along the smooth geomembrane-soil interface. It is important to use the appropriate values of interface shear strength parameters in the design of slopes incorporating one or more geomembranes in contact with soils. The parameters are determined by conducting direct shear test on the geomembrane-soil interface. Laboratory tests of interface shear strength for geomembranes and soil are typically carried out with no provision for measurement of pore pressures at the soil/geomembrane interface. <p>This thesis deals with study of smooth geomembrane-soil interfaces, particularly under unsaturated conditions. The various factors that affect the interface shear behaviour are also studied. The tests were conducted using a modified direct shear box with a miniature pore pressure transducer installed adjacent to the surface of the geomembrane. Geomembranesoil interface shear tests were carried out with continuous measurement of suction in close proximity to the interface during the shearing process thus making it possible to analyze test results in terms of effective stresses. The method was found to be suitable for unsaturated soils at low values of matric suction. <p>Results of interface shear tests conducted using this method show that it is quite effective in evaluating interface shear behaviour between a geomembrane and an unsaturated soil. The results suggest that soil suction contributes to shearing resistance at low normal stress values. At lower normal stress values, the interface shear behaviour appears to be governed only by the magnitude of total normal stress. <p> At high normal stresses, the failure mechanism changed from soil particles sliding at the surface of geomembrane to soil particles getting embedded into the geomembrane and plowing trenches along the direction of shear. A plowing failure mechanism resulted in the mobilization of significantly higher shear strength at the geomembrane soil interface. It was found that placement water contents near saturated conditions results in lower effective stresses, a shallower plowing mechanism and lower values of mobilized interface shear strength.

Geomembranes are one of the most widely used geosynthetics in various civil engineering applications. Their primary function is as a barrier to liquid or vapour flow. Smooth Geomembranes are frequently used in combination with different soils, and due to their low surface roughness, are challenging to design to ensure adequate shear strength along the smooth geomembrane-soil interface. It is important to use the appropriate values of interface shear strength parameters in the design of slopes incorporating one or more geomembranes in contact with soils. The parameters are determined by conducting direct shear test on the geomembrane-soil interface. Laboratory tests of interface shear strength for geomembranes and soil are typically carried out with no provision for measurement of pore pressures at the soil/geomembrane interface. <p>This thesis deals with study of smooth geomembrane-soil interfaces, particularly under unsaturated conditions. The various factors that affect the interface shear behaviour are also studied. The tests were conducted using a modified direct shear box with a miniature pore pressure transducer installed adjacent to the surface of the geomembrane. Geomembranesoil interface shear tests were carried out with continuous measurement of suction in close proximity to the interface during the shearing process thus making it possible to analyze test results in terms of effective stresses. The method was found to be suitable for unsaturated soils at low values of matric suction. <p>Results of interface shear tests conducted using this method show that it is quite effective in evaluating interface shear behaviour between a geomembrane and an unsaturated soil. The results suggest that soil suction contributes to shearing resistance at low normal stress values. At lower normal stress values, the interface shear behaviour appears to be governed only by the magnitude of total normal stress. <p> At high normal stresses, the failure mechanism changed from soil particles sliding at the surface of geomembrane to soil particles getting embedded into the geomembrane and plowing trenches along the direction of shear. A plowing failure mechanism resulted in the mobilization of significantly higher shear strength at the geomembrane soil interface. It was found that placement water contents near saturated conditions results in lower effective stresses, a shallower plowing mechanism and lower values of mobilized interface shear strength.

Slope movements cause considerable damage to life and property in Turkey as well as in the world. Although they do not typically cause loss of life, slow landslide movements can severely damage structures, interrupt the serviceability of lifelines / and, related stabilization efforts can be too costly. Most of these slow-moving landslides are reactivated landslides in stiff clays and shales, and they are mainly triggered by rainfall induced high pore water pressures. In this study, a number of reactivated, slow-moving landslide case histories with extensive pore pressure and movement data are selected for further analysis. For these landslides, the relation between pore water pressures, factor of safety and rate of movements of the slide are investigated by using limit equilibrium and finite element methods. It is found that there is a nonlinear relationship between these three variables. Sensitivity of slow moving landslides to changes in pore water pressure is developed by defining the percent change in factor of safety and percent change in pore pressure coefficient, for 10-fold change in velocity. Such relations could especially be useful in planning required level of remediation, for example, to decide on how many meters the ground water level should be lowered at a certain piezometric location, so that the stability increases to a desired level of F.S., and movement rates are reduced to an acceptable slow rate.

Prairie Creek Reservoir in east central Indiana serves as a secondary water supply for the city of Muncie and is also used as a recreational facility. Due to water quality concerns, this study was conducted to characterize spatial and temporal variability of physical and chemical parameters, specifically nutrients, in the sediment interstitial (pore) water at three reservoir locations. The pH, temperature, specific conductivity, ammonia, nitrates, total nitrogen, orthophosphates and total phosphorus, were monitored twice per month from June through September 2006. Spatial variations in the sediment interstitial water were evident for all water quality parameters, except phosphorus and orthophosphates. Variability in temporal nutrient concentrations in pore water was most likely affected by decomposition of organic matter and presence of anoxic conditions in the overlying water. The results showed high internal nutrient loading, especially from phosphorus, in the sediment interstitial water. Under anoxic conditions, these excessive nutrient concentrations within the sediment can be released into the water column and exacerbate eutrophication of the reservoir. This study provides useful assessment of internal nutrient loading in the Prairie Creek Reservoir sediment that should be considered in the implementation of land management strategies and future land development practices in the reservoir watershed. / Department of Natural Resources and Environmental Management

Thesis (Ph.D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 235-249). / Microfiche. / xx, 249 leaves, bound ill., maps 29 cm

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 119-127).

Thesis (M.S.)--San Jose State University, 1997. / Includes abstract. Includes bibliographical references (leaves 112-122).

Thesis (M. Eng.(Geotechnical Engineering))--University of Pretoria, 2003. / Includes bibliographical references.

No presente trabalho analisa-se o comportamento do aço de reforço ante à corrosão, com o uso dos inibidores: nitrito de sódio, fosfato de sódio e etalonamina, na água de poros contaminada com cloreto, e no concreto com a finalidade de analisar seus resultados e seus mecanismos diferenciados. Para cumprir este objetivo o presente trabalho divide-se em duas etapas: uma primeira etapa baseada em simular sinteticamente a água de poro de um concreto, cuja solução é KOH 28g/l+NaOH 4g/l. Essa água de poro é simulada em ambiente marinho, cuja solução é KOH 28g/l + NaOH 4g/l+NaCl 35g/l, e a esta solução referência incorporamse os inibidores (20g/l da cada um). Realizaram-se ensaios de espectroscopia de impedância eletroquímica (EIE) (após 3 e 72 horas de imersão) e curvas de polarização (após 72 horas de imersão) com vistas a obter respostas da cinética da corrosão ante a cada solução. Obteve-se o melhor comportamento para a água de poros. No caso da água de poro contaminada por cloretos, o melhor comportamento se obteve para o inibidor nitrito de sódio. Na segunda etapa adotou-se apenas o inibidor nitrito de sódio, pois estatisticamente as eficiências dos três inibidores foram muito similares. Analisou-se o nitrito de sódio em amostras reais de concreto armado contaminado com cloreto de sódio. Para isso se elegeram dois tipos de cimentos (CP IV e CP V) e três relações água-cimento (a/c-0.4, a/c-0.5, a/c- 0.65). Para simular o ambiente marinho, realizaram-se ensaios acelerados de cloretos. Comparam-se métodos de análises simuladas sinteticamente e reais, concluindo-se em ambos meios, embora fossem um solido e outro líquido o inibidor Nitrito de Sódio aumento a sua eficiência com os ciclos de exposição. / In this paper it is analyzed the behavior of reinforcing steel against corrosion using inhibitors: sodium nitrate, sodium phosphate and ethanolamine in water contaminated with chlorides pore and concrete, in order to analyzing the results and different mechanisms. To meet the objective of this work, it was divided into two stages, a first stage based on synthetically simulate the pore water of a concrete, through the following solution KOH 28g/l+NaOH 4g/l, this same solution simulated pore water to a marine environment it would be KOH 28g/l + NaOH 4g/l+NaCl 35g/l, it is then incorporated into both reference solutions inhibitors in a proportion, (20g/l de cada um). Assays were performed electrochemical impedance spectroscopy (EIE) (last 3 hours and 72 hours of immersion) and polarization curves (last 72 hours of immersion) in order to obtain responses corrosion kinetics in each solution. the best performance was obtained in the pore water. In the case of water contaminated with chlorides pore, the best performance was obtained in the presence of sodium nitrite inhibitor. In the second step was performed only with the inhibitor sodium nitrate, as statistically efficiencies of the three inhibitors were similar. Sodium nitrate was analyzed in real samples of reinforced concrete contaminated with chlorides of sodium. So they were chosen two types of cement CP- IV and CP-V, cement water three relationships 0.4, a/c-0.5, a/c- 0.65. In this case to simulate the marine environment, accelerated tests were performed chloride. They were compared the methods of analysis, simulated synthetically and simulated in real concrete.

The difficulty of assessing risk of sediment-associated contaminant mixtures to benthic ecosystems is often attributed to understanding the bioavailable fraction of each contaminant. These issues have led to the development of the toxicity identification evaluation (TIE). Past pore water TIE testing on Illinois River sediments has indicated that ammonia was the primary contaminant. The current study, however, suggests that ammonia is no longer the primary contaminant of concern, but rather non-polar organics, including polycyclic aromatic hydrocarbons, are the primary cause for toxicity in the Illinois River Complex (IRC). Summer of 2007 testing showed that six out of the seven sites that proceeded to Phase I testing exhibited a significant increase in survival with the addition of the non-polar organic amendment powdered coconut charcoal (PCC), while zeolite (ammonia amendment) and Resin Tech SIR 300 (cationic metals amendment) did not significantly increase survival suggesting that non-polar organics are the source of toxicity. In addition, Phase II testing suggested that concentrations of PAHs were high enough to cause the observed toxicity, which confirmed the results of Phase I testing. Additional seasonal-based sampling (i.e., fall, winter, spring, and summer 2008) supported the summer findings, with little variation between toxicity and concentrations, with 46% of the sites being improved with the addition of PCC in Phase I testing. The results of Phase I and Phase II contradicted past pore water TIE studies as non-polar organics were suggested as the source of toxicity rather than ammonia. Thus, both pore water and whole sediment TIE methodologies were used on two selected sites. The results of this study suggested that discordance between the past pore water TIEs and the current whole sediment TIE were attributed to the methodologies and on a lesser note the test organisms used. The present study provides data that could be used in combination with previous work to more accurately characterize the sources and spatial trends of toxicity in Illinois River sediments for future risk assessment and mitigation. Furthermore, the present study showed that while TIE methodologies are a valuable tool in assessing risk associated with contaminants in aquatic system, further research in understanding the role that each TIE method may serve in risk assessment is also important.