The physical response of composite landfill liners consisting of a geomembrane on top of a geosynthetic clay liner (GCL) are examined under simulated landfill conditions. The deformation and strains of a 1.5-mm-thick high-density polyethylene geomembrane and thickness and hydraulic performance of a nominally 7-mm-thick GCL are quantified when the composite liner was buried beneath 50 mm coarse gravel, at applied pressures up to 1000 kPa, with a firm sand foundation layer, and with and without a wrinkle in the geomembrane. At an applied pressure of 250 kPa, with either no protection or conventional thick nonwoven needle-punched geotextile protection layers, the tensile strains in the geomembrane exceeded a 3% allowable limit and the GCL was reduced in thickness to as little as 2.2 mm from extrusion of bentonite beneath a gravel particle. Whereas a 150-mm-thick sand protection layer limited strains in the geomembrane to 0.1% and prevented extrusion in the GCL so that deformation was from bentonite consolidation and not from extrusion. A GCL with a thickness of less than 3 mm from extrusion was shown to be susceptible to failure from internal erosion of bentonite in the GCL at hydraulic head differences across the GCL between 1-10 m. Conversely with the sand protection layer, the GCL could withstand a head difference of greater than 100 m without any evidence of internal erosion. Further, the permittivity of an extruded 3.5-mm-thick GCL was found to be 4.5 times larger than a 7-mm-thick GCL that did not experience extrusion. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2008-09-05 10:47:21.783

Este trabalho trata do desenvolvimento, montagem e teste de equipamentos para ensaios de materiais de baixa condutividade hidráulica, o qual inclui sistemas de controle hidráulico de volume constante, permeâmetros do tipo parede flexível e interfaces água-percolante. A vantagem desse arranjo está no maior controle dos ensaios e, notadamente, na redução do tempo de ensaio com emprego do sistema hidráulico de volume constante (sistema fechado), quando comparado aos ensaios que empregam o sistema aberto de controle hidráulico. Para testar o equipamento, foram ensaiados geocompostos bentoníticos (geosynthetic clay liners - GCLs) de fabricação nacional, em corpos de prova moldados com diâmetro de 100 mm e também, em uma mistura de solo com bentonita. Os resultados da condutividade hidráulica obtidos para os geocompostos bentoníticos se situaram na ordem de \'10 POT.-9\' e \'10 POT.-10\' cm/s, compatíveis com os publicados na literatura sobre o material, e os ensaios na mistura solo-bentonita produziu resultados na ordem de \'10 POT.-8\' cm/s, e foram conseguidos com cerca de 3 horas de ensaio. Aborda-se ainda a aplicabilidade da lei de Darcy aos materiais ensaiados. / This work describes the development, construction, calibration and test of equipment for testing low hydraulic conductivity materials, which includes constant volume hydraulic control system, flexible wall permeameters and permeating water interfaces. The advantage of this kind of apparatus is the greater test control, notably, the reduction of test duration due to the use of a constant volume hydraulic system (closed system), when compared to the opened system hydraulic control test. In order to test the equipment, geosynthetic clay liners (GCLs) manufactured in Brazil was used as test specimens of 100 mm diameter and also, a mixture of soil and bentonite. The results of hydraulic conductivity obtained for the GCL were in the range of \'10 POT.-9\' to \'10 POT.-10\' cm/s, comparable to what has been published by the specialized literature on this material, and the tests with the soil-bentonite mixture resulted in a conductivity about \'10 POT.-8\' cm/s, after 3 hours running the test. The applicability of Darcy´s law to the tested materials is also referred to.

Este trabalho trata do desenvolvimento, montagem e teste de equipamentos para ensaios de materiais de baixa condutividade hidráulica, o qual inclui sistemas de controle hidráulico de volume constante, permeâmetros do tipo parede flexível e interfaces água-percolante. A vantagem desse arranjo está no maior controle dos ensaios e, notadamente, na redução do tempo de ensaio com emprego do sistema hidráulico de volume constante (sistema fechado), quando comparado aos ensaios que empregam o sistema aberto de controle hidráulico. Para testar o equipamento, foram ensaiados geocompostos bentoníticos (geosynthetic clay liners - GCLs) de fabricação nacional, em corpos de prova moldados com diâmetro de 100 mm e também, em uma mistura de solo com bentonita. Os resultados da condutividade hidráulica obtidos para os geocompostos bentoníticos se situaram na ordem de \'10 POT.-9\' e \'10 POT.-10\' cm/s, compatíveis com os publicados na literatura sobre o material, e os ensaios na mistura solo-bentonita produziu resultados na ordem de \'10 POT.-8\' cm/s, e foram conseguidos com cerca de 3 horas de ensaio. Aborda-se ainda a aplicabilidade da lei de Darcy aos materiais ensaiados. / This work describes the development, construction, calibration and test of equipment for testing low hydraulic conductivity materials, which includes constant volume hydraulic control system, flexible wall permeameters and permeating water interfaces. The advantage of this kind of apparatus is the greater test control, notably, the reduction of test duration due to the use of a constant volume hydraulic system (closed system), when compared to the opened system hydraulic control test. In order to test the equipment, geosynthetic clay liners (GCLs) manufactured in Brazil was used as test specimens of 100 mm diameter and also, a mixture of soil and bentonite. The results of hydraulic conductivity obtained for the GCL were in the range of \'10 POT.-9\' to \'10 POT.-10\' cm/s, comparable to what has been published by the specialized literature on this material, and the tests with the soil-bentonite mixture resulted in a conductivity about \'10 POT.-8\' cm/s, after 3 hours running the test. The applicability of Darcy´s law to the tested materials is also referred to.

A laboratory test program was conducted to determine the moisture-suction relationships of geosynthetic clay liners (GCLs). Moisture-suction relationships were determined by combining suction data from pressure plate tests, contact filter paper tests, and relative humidity tests, then fitting water retention curves (WRCs) to the data. WRCs were determined for wetting processes and drying processes in terms of gravimetric moisture content and volumetric moisture content. The effects of GCL type, hydration solution, wet-dry cycles, and temperature on the moisture-suction relationships were analyzed. The three GCLs of the test program consisted of configurations of woven and nonwoven geotextiles reinforced with needlepunched fibers. A geofilm was adhesively bonded to the nonwoven side of one of the GCL products. The hydration solution tests involved hydrating GCLs with deionized water, tap water, 0.1 M CaCl2, or soil water from a landfill cover test plot for a 30-day conditioning period prior to testing. Cyclic wet-dry tests were conducted on the GCL specimens subjected to 20 wet-dry cycles from 50% to 0% gravimetric moisture content prior to testing. Temperature tests were conducted at 2°C, 20°C, and 40°C. GCL type affected moisture-suction relationships. The GCLs with an adhesively-bonded geofilm exhibited lower air-entry suction and higher residual suction than GCLs without a geofilm. The degree of needlepunched fiber pullout during hydration contributed to hysteresis between wetting WRCs and drying WRCs. Hysteresis was high for suction values below air-entry suction and was low for suction values greater than air-entry suction. Cation exchange reduced the water retention capacity for all three GCL types. The saturated gravimetric moisture contents were reduced from approximately 140% to 70% for wetting WRCs and 210% to 90% for drying WRCs for GCLs hydrated in deionized water compared to CaCl2 solution. Hysteresis of the nonwoven product decreased from 71%, to 62%, to 28% with respect to deionized water, tap water, and CaCl2 solution. Hysteresis of the woven product exposed to soil water was 24% and 0%, in terms of saturated gravimetric moisture content and saturated volumetric moisture content, respectively. The swell index, Atterberg Limits, mole fraction of bound sodium, and scanning electron microscopy images that were determined of bentonite from the conditioned GCLs indicated that changes in water retention capacity corresponded with cation exchange. Wet-dry cycles and temperature affected the moisture-suction behavior for GCLs. Wet-dry cycles reduced hysteresis and increased the swelling capacity of GCL specimens. Microscopy images indicated that wet-dry cycles caused weak orientation of the clay particles. Increasing temperature resulted in a small decrease in water retention capacity. Results of the test program provided a means for predicting unsaturated behavior for GCLs.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第18435号 / 地環博第117号 / 新制||地環||23(附属図書館) / 31293 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 勝見 武, 教授 高岡 昌輝, 准教授 乾 徹 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

No description available.

A laboratory investigation was conducted to determine the effects of temperature and moisture on the shear strength of textured geomembrane (T-GM) and geosynthetic clay liner (GCL) interface. Several landfill slope failures involving geosynthetics have occurred within the past three decades. Interface shear strength of T-GM/GCL is well documented for testing conducted at laboratory temperatures and at moisture contents associated with GCLs in submerged conditions. However, in-service conditions for landfill liner systems include a wide range of temperatures (extending from below 0 °C to above 40 °C) and a wide range of moisture conditions. Large-scale interface direct shear tests were performed at normal stresses of cover liners (10, 20, and 30 kPa) and bottom liners (100, 200, and 300 kPa). Cover liner specimens were subjected to temperatures of 2, 20 and 40 °C; and bottom liner specimens were subjected to temperatures of 20 and 40 °C. Both cover and bottom liner specimens were prepared at moisture contents of as-received (approx. 18-19%), 50%, and 100%. Cover liner specimens exhibited decreased peak interface shear strength (tp) with increasing temperature. Specimens sheared at 2 °C exhibited greater tp than those sheared at 20 °C by as much as 27%. Specimens sheared at 20 °C exhibited greater tp than those sheared at 40 °C by as much as 16%. Large-displacement interface shear strength (tld) generally exhibited a bell-shaped relationship with increasing temperature with the greatest tld at 20 °C. A bell-shaped relationship was exhibited between temperature and peak and large-displacement interface friction angle (dp and dld). dp ranged from 17.4 to 26.3°, 23.8 to 29°, and 20.4 to 22.2° for 2, 20, and 40 °C, respectively. dld ranged from 12.7 to 18.2°, 18.2 to 20.6°, and 15.9 to 16.7° for 2, 20, and 40 °C, respectively. Decreased d at 2 and 40 °C were largely attributed to increased geosynthetic damage. Bottom liner specimens exhibited decreased tp and tld with increasing temperature by up to 12% and 16%, respectively. Bottom liner specimens exhibited decreased tp and tld with increasing moisture content by up to 14% and 36%, respectively. For bottom liner specimens, a trend of decreased dp with increased temperatures was exhibited. dp ranged from 20 to 24.7° and 19.5 to 22.2° for 20 °C and 40 °C, respectively. dld ranged from 10.4 to 15.6° and 8.9 to 13.9° for 20 °C and 40 °C, respectively. Decreased d at 40 °C was largely attributed to increased geosynthetic damage and increased bentonite extrusion. Increased moisture content resulted in decreased dp and dld by up to 4.7 and 5.1°, respectively. Results of this testing program indicated that T-GM/GCL interface shear strengths are influenced by temperature and moisture content within ranges representative of field conditions. Interpolation factors and reduction factors were developed for use to avoid overestimation of d when determined at standard laboratory temperatures. For cover liners, reduction factors of 0.8 and 0.85 are recommended for dp and dld, respectively. For bottom liners, reduction factors of 0.9 and 0.85 are recommended for dp and dld, respectively.

The use of geosynthetic clay liners (GCLs) as (i) covers for arsenic-rich gold mine tailings and landfills, (ii) subsurface barrier for migration of hydrocarbons in the Arctic, and (iii) basal liner for sewage treatment lagoons were examined. After 4 years in field and laboratory experiments, it was found that best cover configuration above gold mine tailings might include a layer of GCL product with polymer-enhanced bentonite and a geofilm-coated carrier geotextile serving above the tailings under ≥ 0.7 m overburden. However, acceptable performance could be achieved with using a standard GCL with untreated bentonite provided that there is a minimum of 0.7 m of cover soil above the GCL. When GCL samples were exhumed from experimental landfill test cover with complete replacement of sodium in the bentonite with divalent cations in the adjacent soil, it was observed that the (i) hydraulic head across the GCLs, (ii) size of the needle-punched bundles, and (iii) structure of the bentonite can all significantly affect the value of the inferred in-situ hydraulic conductivity measured at the laboratory. The higher the hydraulic head and the larger the size of the needle-punched bundles, the higher the likelihood of internal erosion/structural change of bentonite at bundles that will cause a preferential flow for liquids to occur. A key practical implication was that GCLs can perform effectively as a single hydraulic barrier in covers provided that the water head above the GCL kept low. The hydraulic performance of a GCL in the Arctic was most affected by the location within the soil profile relative to the typical groundwater level with the highest increase in the hydraulic conductivity (by 1-4 orders of magnitude) for GCL below the water table. However, because the head required for jet fuel to pass through the GCL was higher than that present under field conditions, there was no evidence of jet fuel leakage through the barrier system. The leakage through GCLs below concrete lined sewage treatment lagoons was within acceptable limits, in large part, due to the low interface transmissivity between GCLs and the overlying poured concrete. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2014-02-28 08:53:29.171

Neste trabalho analisa-se o comportamento de duas configurações de liners através da percolação com solução de \'K\'CL\'. São utilizadas amostras de solo compactadas, do interior do estado de São Paulo, provenientes da Formação Corumbataí, combinadas a um geocomposto bentonítico (GCL) de fabricação nacional. São utilizados ensaios em coluna de percolação em dois corpos-de-prova, nas configurações: solo compactado acima do GCL e solo compactado abaixo do GCL. Esses ensaios permitiram a determinação da condutividade hidráulica e dos parâmetros de transporte dos materiais estudados. Dessa forma, compara-se o comportamento desses materiais combinados com os resultados obtidos por Musso (2008), que adotou a configuração independente. Após o início da percolação com solução \'K\'CL\' a condutividade hidráulica (\'K\') das duas configurações apresentou comportamento crescente. No entanto, este aumento no \'K\' não afetou o desempenho hidráulico dos materiais, e a condutividade hidráulica mostrou-se com valores da ordem de \'10 POT.-11\' m/s. O fator de retardamento da configuração na qual o GCL encontra-se acima da camada de solo compactado se mostrou maior com relação à outra configuração analisada. No geral, considerou-se que esta configuração apresentou melhor desempenho como liner composto. Na comparação dos resultados obtidos nesta pesquisa com os apresentados por Musso (op. cit.) a condutividade hidráulica não diferiu, e as configurações de liner compostos apresentaram maiores fatores de retardamento do que o liner do solo compactado isoladamente. / This research analyzes the behavior of two sets of liners subjected to the percolation of \'K\'CL\' solution. Samples of compacted soil from Corumbataí Formation, combined with a geosynthetic clay liner (GCL) of brazilian manufacture were used. Column percolation tests were used in two specimens, in the settings: compacted soil above the GCL and compacted soil below the GCL. These tests allowed the determination of hydraulic conductivity and transport parameters of the materials under study. Thus, the behavior of these composite liners was compared with the results obtained by Musso (2008), which tested the independent configuration. After the start of percolation of the \'K\'CL\' solution the hydraulic conductivity (\'K\') of the two settings showed an increase. However, this increase in \'K\' did not affect the hydraulic performance of materials, and the hydraulic conductivity was observed with values of about \'10 POT.-11\' m/s. The retardation factor of the configuration in which the GCL is above the layer of compacted soil was larger in relation to the other configuration analyzed. Overall, it was considered that this configuration showed better performance as composite liner. Comparing the results with those presented by Musso (2008), the hydraulic conductivity didn\'t differ, and the composite liners had higher retardation factors than the liner of compacted soil alone.

Neste trabalho analisa-se o comportamento de duas configurações de liners através da percolação com solução de \'K\'CL\'. São utilizadas amostras de solo compactadas, do interior do estado de São Paulo, provenientes da Formação Corumbataí, combinadas a um geocomposto bentonítico (GCL) de fabricação nacional. São utilizados ensaios em coluna de percolação em dois corpos-de-prova, nas configurações: solo compactado acima do GCL e solo compactado abaixo do GCL. Esses ensaios permitiram a determinação da condutividade hidráulica e dos parâmetros de transporte dos materiais estudados. Dessa forma, compara-se o comportamento desses materiais combinados com os resultados obtidos por Musso (2008), que adotou a configuração independente. Após o início da percolação com solução \'K\'CL\' a condutividade hidráulica (\'K\') das duas configurações apresentou comportamento crescente. No entanto, este aumento no \'K\' não afetou o desempenho hidráulico dos materiais, e a condutividade hidráulica mostrou-se com valores da ordem de \'10 POT.-11\' m/s. O fator de retardamento da configuração na qual o GCL encontra-se acima da camada de solo compactado se mostrou maior com relação à outra configuração analisada. No geral, considerou-se que esta configuração apresentou melhor desempenho como liner composto. Na comparação dos resultados obtidos nesta pesquisa com os apresentados por Musso (op. cit.) a condutividade hidráulica não diferiu, e as configurações de liner compostos apresentaram maiores fatores de retardamento do que o liner do solo compactado isoladamente. / This research analyzes the behavior of two sets of liners subjected to the percolation of \'K\'CL\' solution. Samples of compacted soil from Corumbataí Formation, combined with a geosynthetic clay liner (GCL) of brazilian manufacture were used. Column percolation tests were used in two specimens, in the settings: compacted soil above the GCL and compacted soil below the GCL. These tests allowed the determination of hydraulic conductivity and transport parameters of the materials under study. Thus, the behavior of these composite liners was compared with the results obtained by Musso (2008), which tested the independent configuration. After the start of percolation of the \'K\'CL\' solution the hydraulic conductivity (\'K\') of the two settings showed an increase. However, this increase in \'K\' did not affect the hydraulic performance of materials, and the hydraulic conductivity was observed with values of about \'10 POT.-11\' m/s. The retardation factor of the configuration in which the GCL is above the layer of compacted soil was larger in relation to the other configuration analyzed. Overall, it was considered that this configuration showed better performance as composite liner. Comparing the results with those presented by Musso (2008), the hydraulic conductivity didn\'t differ, and the composite liners had higher retardation factors than the liner of compacted soil alone.