The mechanism of soil-reinforcement interaction for a reinforced embankment on soft clay has been explored by conducting a parametric study using a coupled non-linear elastoplastic finite element program. One of the major issues in the design of a reinforced embankment on soft clay is the magnitude of tension that can be mobilized in the geosynthetic reinforcement. Previous research using geotechnical centrifuge modelling and present research using finite element modelling has confirmed that the tension mobilized in the reinforcement is only of the order of active lateral thrust in the embankment. The parametric study has revealed that the soil-reinforcement interaction mechanism depends on the ratio of embankment height to the depth of the clay layer. The embankment behaves similar to a rigid footing in case of deep clay deposit. In this case, the failure mechanism is similar to a slip circle and there is very little contribution from the clay-reinforcement interface towards the mobilization of reinforcement tension. However, if the depth of clay deposit is small, the soil-reinforcement interaction mode is similar to direct shear failure and slip surface is located close to the clay-reinforcement interface. In this case, the contribution of clay-reinforcement interface towards the tension mobilized in the reinforcement is higher and therefore, the contribution of the reinforcement towards overall stability of the embankment is greater. Based on the results of the parametric study a novel serviceability criterion is proposed that aims to limit the lateral deformation of the clay foundation at the toe of the embankment by limiting the allowable mobilized tension in the reinforcement. A simple procedure for the evaluation of the efficiency of soil-reinforcement interface for reinforced embankments on soft clays is also proposed. The validity of the proposed serviceability criterion and the design charts was successfully tested using two field case studies. Sackville test embankment constructed to failure in 1989 and a levee test section that remained serviceable after construction in 1987 at Plaquemine, Louisiana were able to confirm the validity of the serviceability criterion proposed in the present study.

The mechanism of soil-reinforcement interaction for a reinforced embankment on soft clay has been explored by conducting a parametric study using a coupled non-linear elastoplastic finite element program. One of the major issues in the design of a reinforced embankment on soft clay is the magnitude of tension that can be mobilized in the geosynthetic reinforcement. Previous research using geotechnical centrifuge modelling and present research using finite element modelling has confirmed that the tension mobilized in the reinforcement is only of the order of active lateral thrust in the embankment. The parametric study has revealed that the soil-reinforcement interaction mechanism depends on the ratio of embankment height to the depth of the clay layer. The embankment behaves similar to a rigid footing in case of deep clay deposit. In this case, the failure mechanism is similar to a slip circle and there is very little contribution from the clay-reinforcement interface towards the mobilization of reinforcement tension. However, if the depth of clay deposit is small, the soil-reinforcement interaction mode is similar to direct shear failure and slip surface is located close to the clay-reinforcement interface. In this case, the contribution of clay-reinforcement interface towards the tension mobilized in the reinforcement is higher and therefore, the contribution of the reinforcement towards overall stability of the embankment is greater. Based on the results of the parametric study a novel serviceability criterion is proposed that aims to limit the lateral deformation of the clay foundation at the toe of the embankment by limiting the allowable mobilized tension in the reinforcement. A simple procedure for the evaluation of the efficiency of soil-reinforcement interface for reinforced embankments on soft clays is also proposed. The validity of the proposed serviceability criterion and the design charts was successfully tested using two field case studies. Sackville test embankment constructed to failure in 1989 and a levee test section that remained serviceable after construction in 1987 at Plaquemine, Louisiana were able to confirm the validity of the serviceability criterion proposed in the present study.

Este trabalho apresenta resultados de ensaios de fluência de geotêxteis não tecidos executados em ensaios confinados. No equipamento utilizado, o reforço é confinado entre camadas de solo, permitindo que ambos os materiais tenham liberdade para apresentar deformações ao longo do tempo. Nesses ensaios, uma tensão vertical é aplicada ao solo que por sua vez solicita o reforço. Os ensaios foram realizados com três geotêxteis não tecidos, sendo dois de polipropileno e um de poliéster, e quatro tipos de solo confinante: três materiais granulares e uma argila silto-arenosa. Além disso, também foram executados ensaios de fluência não confinada para permitir comparação com os ensaios confinados. Os resultados indicaram que houve grande contribuição do confinamento na redução das deformações por fluência dos materiais ensaiados. Também foi avaliada a influência de alguns fatores na fluência confinada dos geotêxteis não tecidos, tais como: tipo de solo, tipo de geotêxtil e gramatura do reforço. Tais resultados são interessantes para avaliar o potencial de fluência do composto solo-geotêxtil que, normalmente, é baseado somente em ensaios no elemento isolado de reforço / This work presents results of creep tests on no woven geotextiles tested in confined lab tests. In the used equipment, the reinforcement is confined between two soil layers, allowing both materials to have freedom to deform with time. In those tests, a vertical stress is applied to the soil that transfers load to the reinforcement. The tests were performed using three no woven geotextiles, two of polypropylene and one of polyester, and four types of confining soil: three granular materials and sandy silty clay. Besides, unconfined creep tests were carried out to allow comparison with the confined tests. The results indicated that there was great contribution of the confinement in the reduction of the creep deformations of the tested materials. Also the influence of some factors was evaluated in the confined creep of the no woven geotextiles, such as: soil type, type of geotextile and mass per unit area of the reinforcement. Such results allow the evaluation of the potential of creep of the system soil-geotextile

Este trabalho apresenta resultados de ensaios de fluência de geotêxteis não tecidos executados em ensaios confinados. No equipamento utilizado, o reforço é confinado entre camadas de solo, permitindo que ambos os materiais tenham liberdade para apresentar deformações ao longo do tempo. Nesses ensaios, uma tensão vertical é aplicada ao solo que por sua vez solicita o reforço. Os ensaios foram realizados com três geotêxteis não tecidos, sendo dois de polipropileno e um de poliéster, e quatro tipos de solo confinante: três materiais granulares e uma argila silto-arenosa. Além disso, também foram executados ensaios de fluência não confinada para permitir comparação com os ensaios confinados. Os resultados indicaram que houve grande contribuição do confinamento na redução das deformações por fluência dos materiais ensaiados. Também foi avaliada a influência de alguns fatores na fluência confinada dos geotêxteis não tecidos, tais como: tipo de solo, tipo de geotêxtil e gramatura do reforço. Tais resultados são interessantes para avaliar o potencial de fluência do composto solo-geotêxtil que, normalmente, é baseado somente em ensaios no elemento isolado de reforço / This work presents results of creep tests on no woven geotextiles tested in confined lab tests. In the used equipment, the reinforcement is confined between two soil layers, allowing both materials to have freedom to deform with time. In those tests, a vertical stress is applied to the soil that transfers load to the reinforcement. The tests were performed using three no woven geotextiles, two of polypropylene and one of polyester, and four types of confining soil: three granular materials and sandy silty clay. Besides, unconfined creep tests were carried out to allow comparison with the confined tests. The results indicated that there was great contribution of the confinement in the reduction of the creep deformations of the tested materials. Also the influence of some factors was evaluated in the confined creep of the no woven geotextiles, such as: soil type, type of geotextile and mass per unit area of the reinforcement. Such results allow the evaluation of the potential of creep of the system soil-geotextile

Grande percentagem do território brasileiro é coberta por solos finos (% passando peneira # 200 > 50%), geralmente de origem tropical, que poderiam ser classificados como solos de baixa capacidade de drenagem. Estes solos não atendem às recomendações técnicas para solos de aterro de estruturas reforçadas, conforme exigido pela AASHTO e BS 8006. Neste trabalho foi avaliado experimentalmente um dos parâmetros mais importantes de projeto de Terra Armada, que condiciona o mecanismo de transferência de carga, o coeficiente de atrito aparente solo-fita metálica (f*). Foi avaliada a influência das características dos solos para as classes de solos estabelecidas pela NBR 9286/86 para o caso de fitas metálicas, e, dos critérios que sustentam o uso de fitas poliméricas, sob diversas tensões verticais atuantes nas fitas, simulando o efeito da profundidade. As informações foram obtidas através de ensaios de arrancamento de fitas metálicas e poliméricas realizados em laboratório e depois comparadas aos resultados teóricos da norma e àqueles preconizados para o uso de fitas poliméricas. Os ensaios realizados com as fitas em solo não convencional 1 e em areia mal graduada, mostraram que para profundidades equivalentes a tensões verticais até 50 kPa, os dois tipos de inclusões possuem valores de coeficiente de interação com o solo maiores que a unidade, isso tornaria razoável o seu uso sob o ponto de vista deste parâmetro e nas condições da realização dos ensaios, quando comparado com a norma, e com os critérios que sustentam o uso das fitas poliméricas em técnica de solo armado. No entanto, para maiores profundidades, a interação apresenta uma tendência de diminuição. O solo não convencional 2 valores da interação muito baixos. Foram instalados strain gages ao longo do comprimento das fitas para monitoramento dos esforços no maciço. Nota-se que esforços elevados ocorreram nas regiões mais próximas do ponto de aplicação da força de arrancamento. / A large percentage of Brazil\'s territory is covered with fine tropical soil (50% passing #200) which can be classified as soils with low drainage capacity. These soils do not meet the technical recommendations for backfill of reinforced soil structures by AASHTO and BS 8006. This paper presents the result of an experimental evaluation of one of the most important design parameters of mechanically stabilized earth with concrete wall facing. The apparent friction coefficient of soil-steel strips and soil-polymeric strips is the project parameter. Also was evaluated the influence of soil characteristics for soil types listed by the NBR 9286/86 for metal strips and for the criteria that support the use of polymeric strips. The evaluation included the application of different vertical stresses on the strips simulating the effect of depth. The information obtained from pullout tests performed in laboratory was compared to the standard theoretical values and design values for polymeric strips. Tests performed on strips in nonconventional soil (1) and poorly graded sand showed that at depths equivalent to vertical stresses up to 50 kPa the two types of inclusions have coefficients of interaction greater than unity, which appears reasonable. Therefore, such soils can be used as backfill soils in the conditions tested and at equal or lesser stress levels. Nonconventional soil (2) showed low value of the friction coefficient. The strain gages installed along the length of the strips recorded the distribution of tensile stress in pull-out tests. Higher tensile stress was recorded by the gages nearest the point of application of the pull-out force.

Grande percentagem do território brasileiro é coberta por solos finos (% passando peneira # 200 > 50%), geralmente de origem tropical, que poderiam ser classificados como solos de baixa capacidade de drenagem. Estes solos não atendem às recomendações técnicas para solos de aterro de estruturas reforçadas, conforme exigido pela AASHTO e BS 8006. Neste trabalho foi avaliado experimentalmente um dos parâmetros mais importantes de projeto de Terra Armada, que condiciona o mecanismo de transferência de carga, o coeficiente de atrito aparente solo-fita metálica (f*). Foi avaliada a influência das características dos solos para as classes de solos estabelecidas pela NBR 9286/86 para o caso de fitas metálicas, e, dos critérios que sustentam o uso de fitas poliméricas, sob diversas tensões verticais atuantes nas fitas, simulando o efeito da profundidade. As informações foram obtidas através de ensaios de arrancamento de fitas metálicas e poliméricas realizados em laboratório e depois comparadas aos resultados teóricos da norma e àqueles preconizados para o uso de fitas poliméricas. Os ensaios realizados com as fitas em solo não convencional 1 e em areia mal graduada, mostraram que para profundidades equivalentes a tensões verticais até 50 kPa, os dois tipos de inclusões possuem valores de coeficiente de interação com o solo maiores que a unidade, isso tornaria razoável o seu uso sob o ponto de vista deste parâmetro e nas condições da realização dos ensaios, quando comparado com a norma, e com os critérios que sustentam o uso das fitas poliméricas em técnica de solo armado. No entanto, para maiores profundidades, a interação apresenta uma tendência de diminuição. O solo não convencional 2 valores da interação muito baixos. Foram instalados strain gages ao longo do comprimento das fitas para monitoramento dos esforços no maciço. Nota-se que esforços elevados ocorreram nas regiões mais próximas do ponto de aplicação da força de arrancamento. / A large percentage of Brazil\'s territory is covered with fine tropical soil (50% passing #200) which can be classified as soils with low drainage capacity. These soils do not meet the technical recommendations for backfill of reinforced soil structures by AASHTO and BS 8006. This paper presents the result of an experimental evaluation of one of the most important design parameters of mechanically stabilized earth with concrete wall facing. The apparent friction coefficient of soil-steel strips and soil-polymeric strips is the project parameter. Also was evaluated the influence of soil characteristics for soil types listed by the NBR 9286/86 for metal strips and for the criteria that support the use of polymeric strips. The evaluation included the application of different vertical stresses on the strips simulating the effect of depth. The information obtained from pullout tests performed in laboratory was compared to the standard theoretical values and design values for polymeric strips. Tests performed on strips in nonconventional soil (1) and poorly graded sand showed that at depths equivalent to vertical stresses up to 50 kPa the two types of inclusions have coefficients of interaction greater than unity, which appears reasonable. Therefore, such soils can be used as backfill soils in the conditions tested and at equal or lesser stress levels. Nonconventional soil (2) showed low value of the friction coefficient. The strain gages installed along the length of the strips recorded the distribution of tensile stress in pull-out tests. Higher tensile stress was recorded by the gages nearest the point of application of the pull-out force.

Textilbewehrter Beton zur Verstärkung von Stahlbetonbauteilen ist neben den klassischen und etablierten Verfahren eine äußerst interessante Alternative, die die Vorteile der leichten Kohlenstofffaserklebeverstärkungen mit denen von Spritzbeton mit Bewehrung verbindet. Aus den theoretischen und experimentellen Untersuchungen in dieser Arbeit können wichtige Erkenntnisse zum gemeinsamen Tragverhalten von Betonstahl und textiler Bewehrung sowie zu den Auswirkungen der verbundbedingten Unterschiede abgeleitet werden. Mit den theoretischen Betrachtungen werden das gemeinsame Tragverhalten und der Einfluss des unterschiedlichen Verbundverhaltens auf die Zugkraftaufteilung gezeigt und qualifiziert. Die Behandlung der verbundbedingten Unterschiede bei gemischt mit Betonstahl und Textil bewehrten Zuggliedern ist analog dem Vorgehen bei gemischter Beton- und Spannstahlbewehrung bzw. Klebebewehrung mit Verbundbeiwerten darstellbar. Zur Ableitung entsprechender Kennwerte werden verschiedene Möglichkeiten diskutiert. Zudem wird eine vereinfachte Bemessung vorgeschlagen. Insgesamt sind die Ergebnisse ein wesentlicher Schritt auf dem Weg zur baupraktischen Anwendung von Textilbetonverstärkungen und ermutigen bereits zum umsichtigen Einsatz unter Beachtung der Sicherheitsaspekte. Noch offene Fragen und notwendiger Klärungsbedarf sollten die Wissbegier anregen und vertiefende Forschungsvorhaben und weitere experimentelle Untersuchungen ermöglichen. / Textile reinforcement represents an excellent alternative to existing techniques for strengthening of concrete structures, combining the benefits of lightweight fiber reinforced polymer strengthening with those of shotcrete with reinforcement. The theoretical and experimental studies in this thesis provide essential insights into the common load bearing behaviour of reinforcing steel and textile reinforcements as well as on the impact of the different bond characteristics of both types of rein-forcement. With the theoretical investigations, the combined load bearing behaviour and the influence of the different bond characteristics on distribution of the forces could be shown and qualified. The inter-action of both reinforcement types, taking into account the different bond characteristics, can be represented by bond coefficients analogous to the approach to mixed steel and pre-stressing-steel reinforcements. So as to derive the appropriate parameters, several options were discussed. Moreover, a simplified approach to design a TRC-strengthening-layer was proposed. Overall, the results are an essential step towards the practical application of textile reinforced con-crete for the strengthening of concrete structures and should already be encouraging the prudent use while considering the necessary safety aspects. Remaining issues and necessary clarifications should stimulate curiosity and in-depth research projects and allow further experimental studies.

Textile Bewehrungen stellen eine hervorragende Alternative zu bisherigen Verstärkungsmethoden dar. Die Wirksamkeit von Textilbetonverstärkungen konnte bereits eindrucksvoll nachgewiesen werden. Um sowohl die vorhandene Bausubstanz, als auch die Verstärkung optimal auszulasten, ist es erforderlich, das Zusammenwirken beider Bewehrungsarten unter Berücksichtigung der unterschiedlichen Verbundeigenschaften zu beschreiben. In diesem Beitrag wird das gemeinsamen Tragverhalten von Betonstahl und textiler Bewehrung eingehend erläutert. Zur Veranschaulichung wird daher vor allem die Verbundtragwirkung und deren Einfluss auf gerissene Zugglieder genauer untersucht.