Este trabalho apresenta um estudo das propriedades de resistência e de deformabilidade dos resíduos sólidos urbanos (RSU). Amostras de resíduo de diferentes idades, obtidas no aterro metropolitano centro (Salvador-BA), foram submetidas a ensaios de compressão triaxial e de compressão confinada em equipamentos de grandes dimensões. Os resultados dos ensaios triaxiais demonstraram que os RSU não apresentam pico ou valor máximo de resistência, mesmo para grandes deformações. Os parâmetros de resistência foram obtidos a partir de níveis específicos de deformação. Não foi possível observar a influência do processo de decomposição na resistência ao cisalhamento do RSU, porém observou-se um aumento de resistência com o acréscimo do peso específico. Dos ensaios em resíduos sem fibras (plásticos, têxteis, etc), verificou-se uma redução nos parâmetros de resistência em comparação com os do resíduo composto, indicando a grande influência do material fibroso no comportamento mecânico do RSU. Ensaios não drenados mostraram grande desenvolvimento de pressão neutra, que provocaram distorções nas envoltórias efetivas, fazendo com que os ângulos de atrito obtidos fossem maiores que aqueles obtidos nos ensaios drenados. Duas amostras de RSU novo foram submetidas a ensaios de compressão confinada. Uma das amostras foi submetida à recirculação de chorume para avaliação do efeito da decomposição nos recalques medidos. Os resíduos apresentaram uma rápida compressão primária e deformações secundárias que se desenvolveram durante todo o ensaio, sem tendência de estabilização. A recirculação de chorume não provocou acréscimos nas deformações secundárias, provavelmente devido ao pequeno volume de chorume utilizado e ao ambiente não favorável à decomposição. / This work deals with the shear strenght and compressibility properties of municipal solid waste (MSW). Four years old end new waste samples recovered from metropolitan center sanitary landfill (Salvador, Brazil) were submitted to triaxial and confined compression tests using large dimension specimens. Triaxial test results showed that a peak or an ultimate shear stress value was not reached even for the largest deformation attained in the tests and thus, shear strength parameters were derived to different strain levels. It was shown that the shear strength was not too much affected by waste decomposition process, but increased with the waste unit weight. The waste without plastic fibres tended to show reduced shear strength as compared to the whole waste, showing the large influence of this materials on MSW mechanical behavior. Undrained tests showed large pore pressures build up and tended to yield effetive shear strength parameters larger than that obtained in drained tests. Confined compression tests were performed using samples of fresh waste with and without leachate recirculation to investigate the influence of the waste degradation on MSW compressibility. It was observed that the waste showed a quick primary compression and secondary compression that extended throughout the test period without reaching equilibrium. The leachate recirculation did not increase secondary defomation probably by the low volume of leachate used during the test and due the ambient conditions not suitable to the degradation.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-26T10:17:46Z No. of bitstreams: 2 Dissertação - Elisandra Miranda de Oliveira - 2008.pdf: 8045679 bytes, checksum: bbc3ccef6840ca7cc9f60fd22a61ed85 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-26T10:18:11Z (GMT) No. of bitstreams: 2 Dissertação - Elisandra Miranda de Oliveira - 2008.pdf: 8045679 bytes, checksum: bbc3ccef6840ca7cc9f60fd22a61ed85 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-26T10:18:12Z (GMT). No. of bitstreams: 2 Dissertação - Elisandra Miranda de Oliveira - 2008.pdf: 8045679 bytes, checksum: bbc3ccef6840ca7cc9f60fd22a61ed85 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2008-09-17 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The joint is part of the constructive process of the rigid pavement. In its implementation the section of concrete located below it is weakened and eventually becoming the most vulnerable of the pavement can arise where the possible diseases that may affect their strength and durability. Despite the importance that the joint has in the life of the rigid pavement it is not exploited, and therefore became the main subject of this study. This work is an experimental study of the sawed joint in rigid pavement of concrete with evaluation of the transference of shear strength through the saweds joints. The experimental program consisted of test of fourteen simple concrete plates with sawed joint, and adoption of the following variable: presence of smooth dowel of Ø 12,5mm, variation of the length of dowel (500 mm, 400 mm and 300 mm), variation of the thickness of the plates (120 mm and 160 mm), variation of the strength to the compression of the concrete (20 MPa and 30 MPa) and of the type of used concrete (conventional and autoadensável). These plates had been supported on natural and assayed rubber layers with static shipment application in one of the sides of the together one until the rupture of the plate. The results had shown that: the use of dowel in these meetings increases the efficiency in the transference of efforts; the increase in the thickness of the plate increases the resistant capacity of the together one, the efficiency in the transference of efforts and possesss minors displacements of the plate during the application of the shipment; the dowel with reduced size are efficient, but the bars of 400 mm present resulted next to the one to the bar in commercial size, 500 mm; the plates in autoadensável concrete after the fissuration practically do not present contribution of the concrete in the transference of efforts for the intertravamento of aggregates; the sawed joint depth of the together one has influence in the way of rupture of the plate and tack relation enters the bar of transference and concret. / A junta faz parte do processo construtivo do pavimento de concreto. Na sua execução a seção de concreto localizada abaixo dela fica enfraquecida e acaba se tornando o ponto mais vulnerável do pavimento onde podem surgir as possíveis patologias que venham a afetar a sua resistência e durabilidade. Apesar da importância que a junta possui na vida útil do pavimento de concreto este assunto é pouco explorado, e por isso se tornou o objeto principal deste estudo. Este trabalho é um estudo experimental das juntas serradas em pavimento rígido de concreto com avaliação da transferência de esforços cisalhantes através das juntas serradas. O programa experimental constou de ensaios de quatorze placas em concreto simples com junta serrada, e adoção das seguintes variáveis: presença de barra de transferência lisa de Ø 12,5mm, variação do comprimento das barras de transferência (500 mm, 400 mm e 300 mm), variação da espessura das placas (120 mm e 160 mm), variação da resistência característica à compressão do concreto (20 MPa e 30 MPa) e do tipo de concreto utilizado (convencional e autoadensável). Essas placas foram apoiadas sobre camadas de borracha natural e ensaiadas com aplicação de carregamento estático em um dos lados da junta até a ruptura da placa. Os resultados mostraram que: o uso de barras de transferência nessas juntas aumenta a eficiência na transferência de esforços; o aumento na espessura da placa aumenta a capacidade resistente da junta, a eficiência na transferência de esforços e possuem menores deslocamentos da placa durante a aplicação do carregamento; as barras com tamanho reduzido são eficientes, mas as barras de 400 mm apresentam resultados próximos ao da barra em tamanho comercial, 500 mm; as placas em concreto autoadensável após a fissuração praticamente não apresentam contribuição do concreto na transferência de esforços pelo intertravamento dos agregados; a profundidade da junta serrada tem influência no modo de ruptura da placa e relação de aderência entre a barra de transferência e o concreto.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-04-27T11:59:34Z No. of bitstreams: 1 2012 - Cintia Silva Nunes.pdf: 1126230 bytes, checksum: 45346dd33d53277fd3bc88d1d3d22157 (MD5) / Made available in DSpace on 2017-04-27T11:59:34Z (GMT). No. of bitstreams: 1 2012 - Cintia Silva Nunes.pdf: 1126230 bytes, checksum: 45346dd33d53277fd3bc88d1d3d22157 (MD5) Previous issue date: 2012-06-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Heat treatment provides desirable characteristics to the wood such as higher dimensional stability, higher natural durability and, in some cases, changes on original color. However, the treatment can also drastically alter the physical and chemical characteristics of wood surfaces, which affect the adhesion quality and coating application. In this context, the objectives of this study were: (1) to evaluate the effect of heat treatmens on physical properties (density, equilibrium moisture content and mass loss) of Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson and Eucalyptus pellita F. Muell. woods; (2) to determine the effect of heat treatment on color change of both woods; (3) to evaluate the effect of heat treatments on adhesion quality of glued joints by shear strength testing; and (4) to evaluate the effect of physical and chemical modifications following heat treatment on adhesion characteristics. Heat treatments were performed in a laboratorial electric oven at 180 and 200?C. Color measurements were carried out on the CIE-L*a*b* space by using the CM-2600d portable spectrophotometer. Shear strength tests of the glued joints and solid woods were performed according to ASTM D 905 and ASTM D 143 standards, respectively. Three adhesive types were used: resorcinol, resorcinol-tannin 80:20 and resorcinol-tannin 60:40. Density and equilibrium moisture content of both wood species were reduzed by heat treatment. Both woods had mass loss, which increased with the increase of temperature and was more pronounced for Eucalyptus pellita. The original color of the woods changed following heat treatment, mainly to Eucalyptus pellita. The shear strength of solid wood and glued joints of both species was severely affected by heat treatments. The resorcinol-tannin 80:20 adhesive showed the best performance for untreated woods, however, after heat treatment, the adhesive type did not affect the shear strength. Glued joints of heat-treated woods had high percentage of wood failure due to higher porosity and adhesive penetration. The acidity of heat-treated woods affected the shear strength and presented a strong correlation with equilibrium moisture content due to degradation of hemicelluloses. Heat treatments at 180 and 200oC are extremely severe to Corymbia citriodora and Eucalyptus pellita woods / O tratamento de termorretifica??o proporciona ? madeira caracter?sticas desej?veis tais como maior estabilidade dimensional, maior durabilidade natural e, em alguns casos, altera??o da cor original. Entretanto, o tratamento tamb?m pode alterar drasticamente as caracter?sticas f?sicas e qu?micas das superf?cies da madeira, as quais afetam a qualidade de ades?o e a aplica??o de revestimentos. Neste contexto, os objetivos deste estudo foram: (1) avaliar o efeito dos tratamentos nas propriedades f?sicas (densidade, teor de umidade de equil?brio e perda de massa) da madeira de Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson e Eucalyptus pellita F. Muell.; (2) determinar o efeito dos tratamentos termorretificadores na altera??o da cor da madeira de ambas as esp?cies; (3) avaliar o efeito dos tratamentos na qualidade de ades?o de juntas coladas atrav?s de testes de resist?ncia ao cisalhamento; e (4) avaliar o efeito das altera??es f?sicas e qu?micas causadas pela termorretifica??o nas caracter?sticas de ades?o. A termorretifica??o foi realizada em um forno mufla el?trico laboratorial a 180 e 200?C. As medi??es de cor foram realizadas no espa?o CIE-L*a*b* com o aux?lio do espectrofot?metro port?til CM-2600d. Os ensaios de cisalhamento das juntas de madeira colada e das madeiras s?lidas foram realizados segundo as normas ASTM D 905 e ASTM D 143, respectivamente. Foram utilizados tr?s tipos de adesivos: resorcinol, resorcinol-tanino 80:20 e resorcinol-tanino 60:40. A densidade aparente e o teor de umidade de equil?brio das madeiras de ambas as esp?cies foram reduzidos pela termorretifica??o. Ambas as madeiras apresentaram perda de massa, sendo esta crescente com o aumento da temperatura e mais acentuada para a madeira de Eucalyptus pellita. A cor original das madeiras foi alterada pelo tratamento, principalmente para o Eucalyptus pellita. A resist?ncia ao cisalhamento da madeira s?lida e das juntas coladas de ambas as esp?cies foi severamente afetada pelos tratamentos termorretificadores. O adesivo resorcinol-tanino 80:20 apresentou o melhor desempenho para as madeiras n?o termorretificadas de ambas as esp?cies; entretanto, ap?s a termorretifica??o, o tipo de adesivo n?o afetou a resist?ncia ao cisalhamento. As juntas coladas das amostras de madeiras termorretificadas apresentaram uma alta porcentagem de falhas na madeira devido ? maior porosidade e maior penetra??o do adesivo. A acidez das amostras da madeira termorretificada afetou a resist?ncia ao cisalhamento e apresentou uma forte correla??o com o teor de umidade de equil?brio devido ? degrada??o das hemiceluloses. Os tratamentos termorretificadores a 180 e 200?C s?o extremamente severos para as madeiras de Corymbia citriodora e Eucalyptus pellita

Neste trabalho estuda-se o comportamento tensão-deformação de dois horizontes de um solo residual de gnaisse, pertencentes a um perfil típico da cidade de Viçosa-Minas Gerais, na condição saturada e sob diferentes valores de sucção. O estudo apóia-se em ensaios de caracterização física e mineralógica, em ensaios destinados às análises porosimétricas e morfológicas (lâminas delgadas), e em ensaios de compressão triaxial realizados em corpos de prova não saturados e saturados, estes sujeitos a diferentes direções de cisalhamento, em ambos solos, e distintas trajetórias de tensão, no solo jovem. Nos ensaios triaxiais saturados mostra-se que a resistência dos dois solos foi independente da direção de cisalhamento e que a deformabilidade revelou-se mais anisotrópica no solo maduro, que no solo jovem, este visualmente mais heterogêneo. Mostra-se, que o intercepto de coesão cresce com a sucção numa relação que pode ser bem representada por uma função hiperbólica e que o ângulo de atrito interno praticamente não apresentou variação com a sucção matricial. Apresenta-se uma alternativa de previsão da envoltória de resistência, baseada nos parâmetros de resistência do solo saturado e nos resultados de ensaio correspondente a uma sucção conhecida. A curva de plastificação do solo jovem pôde ser representada razoavelmente bem pela curva adotada nos modelos derivados da mecânica dos solos dos estados críticos (Cam-Clay modificado). A curva é centrada no eixo hidrostático e sua forma não apresenta mudança marcante durante o encruamento do solo, o qual foi obtido através da união de pontos com o mesmo trabalho plástico. / This thesis deals with the stress-strain behavior of a mature soil and a young soil from a typical residual soil of gneiss, as found in Viçosa-MG. This behavior is analyzed under saturated and non saturated conditions. The study rests on physical and mineralogical characterization tests, on porosimetric and morphological analyses (thin section) and on triaxial compression tests performed with saturated and non saturated soil. Saturated young and mature specimens were sheared according to different directions and saturated young soil was also sheared following various stress path. It is shown that the shear strength of saturated soil, both mature and young is independent of shearing direction. However, the visually more homogeneous mature soil showed to be more anisotropic, regarding the deformability, than the young residual soil that visually seems to be heterogeneous. The cohesion intercept tends to increase with soil suction according to a non linear relationship that can be adjusted through a hyperbolic function, while the angle of shearing stress was not influenced by soil suction. An alternative to forecast unsaturated shear strength envelope based on results of saturated soil and on tests performed at a known suction is also presented. The yielding curve of young soil was found to be fairly predicted using modified Cam-Clay model. The yield curve is centered along the hydrostatic axis of stress and its shape didn’t change during soil strain hardening that was obtained by joining the points to that exhibited the same plastic work.

A compactação de solos em climas com elevada concentração de precipitação apresenta dificuldade que afetam o cronograma físico e financeiro das obras. A execução de aterros com teor de umidade elevado gera solos com grau de saturação elevado que, por sua vez, induz poropressões indesejáveis durante a construção. Assim, o solo é, em geral, compactado no entorno do teor de umidade ótimo (+/- 3%) e densidade seca máxima (GC de 95% a 105%). No entanto, é possível avaliar o solo de modo a possibilitar a compactação acima do teor de umidade ótimo. Estes aterros são chamados aterros úmidos. Os poucos estudos realizados nestas condições encontraram como uma das dificuldades a ausência da medição da sucção durante os ensaios. A medição da sucção logo após a compactação utilizando-se o tensiômetro de alta capacidade (TAC) possibilitou estudos sobre o desenvolvimento da poropressão de água com o carregamento. Utilizando de ensaios triaxiais de umidade constante (CW) e com o uso do TAC é possível se obter as informações importantes para a execução de aterros úmidos. O presente trabalho estuda experimentalmente o comportamento de um solo residual de gnaisse compactado na umidade ótima e em duas condições de compactação acima do teor de umidade ótimo. São realizados ensaios na condição saturada (ensaios CIU) e não saturada (ensaios CW) com medição direta de sucção com o tensiômetro de alta capacidade. O trabalho apresenta um estudo do comportamento dos solos compactados no estado quasi-saturado e avalia os seguintes aspectos: Efeito da técnica da contrapressão para saturação no comportamento mecânico do solo, desenvolvimento da sucção após a compactação e durante ensaios de resistência, correlação entre a curva de retenção de água e o comportamento mecânico do solo, aplicação das equações de Bishop (1959) e Fredlund et al. (1978), procedimento para determinação da superfície de ruptura. O trabalho conclui que o solo residual estudado permite a construção de aterros úmidos sem o desenvolvimento de poropressões de água indesejáveis. Conclui-se ainda que com o uso do TAC associado a ensaios triaxiais CW é possível a obtenção da envoltória de ruptura na condição não saturada de forma simples. / The compaction of soils in climates with high concentration of rainfall has created problems that affect the physical and financial schedule of works. Embankments constructed with soils having high water content generate high degree of saturation, which, in turn, induces undesirable pore water pressures during construction. In general, the soil is compacted in the vicinity of the optimum water content (+/-3 %) and maximum dry density (DC 95% to 105 %). However, it is possible to evaluate the soil behaviour to enable compaction above the optimum moisture content. These embankments are called \"wet landfills\". The few studies carried out in these conditions found difficulties in the measuring of the suction during tests. The measurement of suction immediately after compaction using a high-capacity tensiometer (HCT) allowed studies on the development of the pore-water pressure during loading. Using constant water content triaxial test (CW) and the HCT, it is possible to obtain necessary information to construct a \"wet landfills\". This work experimentally investigate the behaviour of a residual soil of gneiss compacted at three conditions above the optimum moisture content. Tests are performed in the saturated (CIU tests) and unsaturated (CW trials) conditions with direct measurement of suction using a high-capacity tensiometer. The study evaluated the behaviour of a compacted soils in quasi-saturated state and investigating the following aspects: Effect of back-pressure technique for saturation on mechanical behaviour of the soil, development of suction after compaction and during shear tests, correlation between the soil water retention curve and the mechanical behaviour of the soil, evaluation of the use of the equations suggested by Bishop (1959) and Fredlund et al. (1978) for determining the failure surface. The work concludes that the use of the residual soil studied allows the construction of wet landfills without undesirable positive pore-water pressure. In addition, the research concludes that using the high-capacity tensiometer associated with CW triaxial tests is possible to obtain the failure envelope in unsaturated condition in a simple way.

Landslide characterization and hazard assessments require multidisciplinary approaches that connect geologic processes with geotechnical parameters. Field monitoring of hydrologic variables such as water content and water potential, coupled with geoelectrical measurements that can establish relationships used for geotechnical and landslide hazard investigations is deficient. This study brings together different techniques to develop a methodology that connects geoelectrical measurements and shear strength. A field-based framework was established that includes (1) analysis of long-term soil moisture fluctuations within different landslides (2) establishment of constitutive and new equations that test the use of electrical conductivity to predict soil-water relationships and shear strength (3) using electrical resistivity tomography (ERT) to support and facilitate the prediction of shear strength in a slope. Hydrologic conditions including volumetric water content, water potential, and electrical conductivity in the soil were measured at three active landslides in Kentucky. The in-situ electrical conductivity used within the framework is valid as a predictor of suction stress and shear strength. The ERT supports interpretations of landslide failure zones, landslide type, lithologic boundaries, and changes in moisture conditions, but also is able to utilize the methodology to calculate shear strength, and provide a spatial view of shear strength in the slope. The practical application of this framework is to support landslide hazard assessment and further understand the long-term influence of moisture conditions in hillslope soils. These parameters are pertinent to investigating the stability of landslides that are often triggered or reactivated by rainfall.

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.

During shearing of stiff clays, plate-shaped clay particles are parallel-oriented in the direction of shear reaching the minimum resistance of &ldquo / residual shear strength&rdquo / . The residual shear strength envelopes of stiff clays are curved, but for practical purposes represented by linear envelopes. This study investigates the nonlinearity of the residual shear strength envelope using experimental evidence (i) from laboratory reversal direct shear tests on two stiff clays (Ankara clay and kaolinite) at 25 to 900 kPa effective normal stresses and (ii) from laboratory data collected from literature. To evaluate the importance of nonlinearity of the envelope for geotechnical engineering practice, by limit equilibrium method, (a) case histories of reactivated landslides are analyzed and (b) a parametric study is carried out. Conclusions of this study are: (1) The residual shear strength envelopes of both Ankara clay and kaolinite are nonlinear, and can be represented by a power function (cohesion is zero). (2) At least 3 reversals or cumulative 20 mm shear displacement of direct shear box is recommended to reach residual condition. (3) Empirical relations between plasticity index and residual friction angle can accurately estimate the residual strength of stiff clays. (4) Nonlinearity is especially important for landslides where average effective normal stress on the shear plane is less than 50 kPa, both for translational and rotational failures. For such slopes using a linear strength envelope overestimates the factor of safety (more significantly for the case of high pore pressures). (5) As the plasticity index increases, the power &ldquo / b&rdquo / of the nonlinear shear strength envelope decreases, indicating more significant nonlinearity. For less plastic materials, using linear and nonlinear shear strength envelopes does not affect the factor of safety.

El estudio de los parámetros resistentes de los geosintéticos utilizados en los sistemas de impermeabilización de vertederos es un tema muy importante. Estos sistemas contienen diferentes interfaces (geosintético/geosintético y/o suelo/geosintético), muchas de las cuales tienen baja resistencia al deslizamiento. Esto potencia la existencia de superficies de rotura a lo largo de los taludes de los vertederos. El conocimiento de los parámetros resistentes al corte de los contactos entre geosintéticos (geotextiles, geomallas, geomembranas, etc.) y suelo ha sido investigado en la Universidad de Cantabria. Para ello se ha desarrollado una metodología del ensayo de corte directo 300x300 mm entre dos geosintéticos, entre suelo y geosintético, obteniendo los parámetros resistentes de estas interfaces. Seguidamente, en el Instituto de Geotecnia de la Universidad de Freiberg, se ha desarrollado el modelo de comportamiento resistente al corte de la interfaz geomembrana/geotextil. Este modelo se ha implementado en el programa de diferencias finitas FLAC3D para el desarrollo del modelo numérico. Comprobando que existe una excelente concordancia entre resultados de laboratorio, modelo analítico y modelo numérico. / The study of friction of the geosynthetics used for landfills both for basal-liner and capping systems is a very important issue. These lining systems typically contain a large number of material interfaces (geosynthetics/geosynthetics or geosynthetics/soil), many of which have low shear strengths. This introduces potential failure surfaces along the side slopes and base of the fill mass.A research project about this subject has been undertaken at University of Cantabria. In this investigation, a methodology for direct shear tests between two geosynthetics and a soil and a geosynthetic has been developed, achieving the friction parameters and analysing interaction mechanisms of different contacts. Later on at Technical University Bergakademie Freiberg was developed a shear strength model of the geomembrane/geotextile interface. On the one hand a shear model has been developed, on the other this model was introduced in numerical modelling code for advanced geotechnical analysis, FLAC3D. There is an excellent agreement between laboratory results, shear model and numerical model.

Shear strength characterization of discontinuities is an important concept for slope design in discontinuous rocks. This study presents the development of a methodology for implementing Barton-Bandis empirical shear strength failure criterion in three dimensional distinct element code, 3DEC, and verification of this methodology. Normal and shear deformation characteristics of discontinuities and their relations to the discontinuity surface characteristics have been reviewed in detail. First, a C++ dynamic link library (DLL) file was coded and embedded into 3DEC for modelling the Barton-Bandis shear strength criterion. Then, a numerically developed direct shear test model was used to verify the normal and shear deformation behaviour with respect to empirical results of the Barton-Bandis shear strength criterion. A three dimensional simple discontinuous rock slope was modelled in 3DEC based on Barton-Bandis shear strength criterion. The slope model was first utilized by Mohr-Coulomb failure criterion. Then, with the use of the new model developed here, the effects of the discontinuity surface properties on shear strength were introduced to the slope problem. Applicability of the developed model was verified by three large scale real case studies from different open pit lignite mines of Turkish Coal Enterprises (TKi), namely Bursa Lignites Establishment (BLi) &ndash / 2 cases and &Ccedil / an Lignite Establishment (&Ccedil / Li). The results with the new model option, which allows users to use important discontinuity surface properties like joint roughness coefficient and joint wall compressive strength, compared well with results of previous studies using Mohr-Coulomb failure criterion.