Os ensaios de arrancamento e de cisalhamento direto são os ensaios de laboratório mais usados para mensurar a resistência da interface solo geossintéticos. Em algumas ocasiões somente os ensaios de arrancamento avaliam convenientemente bem o comportamento das inclusões em meio ao maciço de solo. Esse trabalho apresenta um equipamento de ensaios de arrancamento em geossintéticos, de grandes dimensões, e resultados de ensaios executados com ele. Os resultados foram analisados segundo uma metodologia sugerida por Ochiai et al. (1996), levemente modificada pelo autor. Dos dados de ensaios de arrancamento, pôde-se concluir que o equipamento se presta à finalidade a que se destina, além disso, analisando-se os resultados segundo o método mencionado, verificou-se que a resistência ao arrancamento de geogrelhas se concentra na sua porção inicial, quando são aplicadas pequenas cargas. À medida que se aumenta a força aplicada, a resistência é gradativamente mobilizada nos trechos posteriores até à ruptura generalizada por arrancamento. / The pull-out and direct shear tests are the more used laboratory test for measure the resistance of soil-geosynthetic interface. In some occasions only the pull-out test evaluate well the behaviour of the inclusions amid the massive of soil. This work presents an pull-out test equipment, of great dimensions, and results of tests executed with him. The results were analysed according to a methodology suggested by Ochiai et al. (1996), slightly modified by the author. From the pull-out tests data, it may be concluded that the equipment is rendered to the purpose that it is destined, besides, being analysed the results according to the mentioned method, it was verified that the pull-out resistance of geogrids concentrates in initial portion, when it is applied small loads. When the applied force increases, the resistance is mobilized in the posterior portions and occur to the generalised pull-out rupture.

O conhecimento dos mecanismos de interação entre o solo e os geossintéticos é fundamental para o dimensionamento de obras em solo reforçado. Entretanto, em função das diferentes formas geométricas das superfícies das inclusões, a interação pode ocorrer de maneiras distintas. Para as geogrelhas, o arrancamento representa o mecanismo de interação que, em alguns casos, melhor retrata as situações que ocorrem no campo. Esta tese apresenta uma análise dos principais fatores que influenciam na interação entre o solo e as geogrelhas quando solicitadas ao arrancamento, utilizando equipamentos de teste de portes grande e pequeno, bem como um equipamento que testa isoladamente os elementos longitudinais e transversais das geogrelhas. Apresenta-se ainda dois modelos numéricos que permitem avaliar o comportamento de geogrelhas de comprimento qualquer a partir de resultados de ensaios de arrancamento de pequeno porte ou dos ensaios nos elementos isolados da geogrelha. Os resultados dos ensaios realizados são comparados entre si, sugerindo a viabilidade de se utilizar equipamentos de pequenas dimensões para executar ensaios de arrancamento em geogrelhas em meio a solos finos, em detrimento dos testes de grande porte que demandam uma grande quantidade de solo e de mão-de-obra para serem executados. Por fim, apresenta-se um método que, utilizando os resultados obtidos dos testes de pequeno porte, pode ser usado para determinar os esforços de tração nas inclusões de estruturas em solo reforçado, considerando aspectos como a interação solo–reforço e a rigidez à tração das inclusões / The knowledge of interaction mechanisms between soil and geosynthetics is fundamental for designing reinforced-soil structures. However, due the variety of surface geometry found in commercially available geosynthetics, the interaction between soil and inclusions can occur on different ways. For the geodrids, the pullout interaction mechanisms is the one that, in some cases, best represents the field situations. This thesis presents an analysis of the main factors influencing the soil-geogrid interaction during pullout phenomena, using large and small-scale test boxes, as well as an device that tests longitudinal and transversal geodrid elements isolated. Two numerical models for evaluating the pullout behavior of large geogrid samples using small-scale and on element tests are also presented. The results of different tests are compared, showing the viability of using small-scale tests for testing geogrids embedded in fine soils instead of large-scale tests, that demand large quantities of soil and labor to be done. On the penultimate chapter, a method for evaluating the maximum tensile effort of reinforced slopes and walls is presented. This method uses the results obtained from small-scale pullout tests and considers some important aspects as soil-geogrid interaction and reinforcement rigidity

A execução de obras apoiadas em solos moles constitui um desafio para a engenharia geotécnica. Pela baixa capacidade de suporte do solo mole, tais obras estão sujeitas a sofrer colapso, geralmente por ruptura do solo de base; e recalques excessivos, que ocorrem ao longo do tempo por efeito do adensamento do solo mole. Em virtude destes problemas, quaisquer soluções que promovam o aumento da capacidade de carga do solo mole representam uma enorme contribuição ao tema. Este trabalho apresenta resultados de uma série de provas de carga realizadas em laboratório sobre uma camada de areia apoiada em solo mole. A camada de areia foi ensaiada em três condições: sem reforço, reforçada apenas por geocélulas e pela associação de geocélulas e geogrelha. Foram utilizadas geocélulas de geotêxtil com ligações costuradas e geocélulas de polietileno com ligações soldadas nas alturas de 5, 10 e 15 cm. Os resultados apontam uma melhora significativa quando do confinamento com geocélulas, tanto em termos de recalque quanto de capacidade de suporte. A utilização de geocélulas conjugadas a um reforço basal com geogrelha permitiu uma melhora do desempenho ainda mais significativa / Works resting on soft soils represent a large task to geotechnical engineers. Due to the soft soil low bearing capacity, such works might present a rotational failure or present large settlements that occurwith time due to consolidation. For these problems any technical contribution that would allow an increase fo the bearing capacity of the soft soils would represent an enormous help to geotechnical engineering. This work presents results of laboratory loading plate tests carried out on a sandy layer resting on the topo of a soft soil deposit. The sandy layer was tested in there different conditions: unreinforced, reiforced with geocells and with geocells and geogrids. Geocells made out of strips of non woven geotextile with sewed joints and made from welded joint poliethylene strips were used. The results of plate tests showed a significant improvement not only in terms of bearing capacity but also in terms of settlement reduction when geocells alonge were used. The use of geocells associated with geogrids allowed further improvements in the bearing capacity and settlement reductions

Loaded wheel tester (LWT) is a common testing equipment usually used to test the permanent deformation and moisture susceptibility of asphalt mixtures by applying moving wheel loads on asphalt mixture specimens. It has been widely used in the United States since 1980s and practically each Department of Transportation or highway agency owns one or more LWT(s). Compared to other testing methods for pavement materials, LWT features movable wheel loads that allow more realistic situations existing on the actual pavement to be simulated in the laboratory. Due to its potential of creating a condition of repetitive loading, the concept of using LWT for characterizing the properties of pavement materials were promoted through four innovative or modified tests in this study. (1) The first test focuses on evaluating the effect of geogrids in reinforcing pavement base courses. In this test, a base course specimen compacted in a testing box with or without geogrids reinforced was tested under cyclic loading provided by LWT. The results showed that LWT test was able to characterize the improvement of the pavement base courses with geogrids reinforcement. In addition, the results from this study were repeatable and generally in agreement with the results from another independent study conducted by the University of Kansas with similar testing method and base materials. (2) A simple and efficient abrasion test was developed for characterizing the abrasion resistance of pervious concrete utilizing LWT. According to the abrading mechanisms for pervious concrete, some modifications were made to the loading system of LWT to achieve better simulations of the spalling/raveling actions on pervious concrete pavements. By comparing the results from LWT abrasion tests to Cantabro abrasion tests, LWT abrasion test was proved effective to differentiate the abrasion resistances for various pervious concretes. (3) Two innovative LWT tests were developed for characterizing the viscoelastic and fatigue properties of asphalt mixtures in this study. In the test, asphalt beam specimens are subjected to the cyclic loads supplied by the moving wheels of LWT, and the tensile deformations of the beam specimens are measured by the LVDTs mounted on the bottom. According to the stress and strain, the parameters associated to the viscoelastic and fatigue properties of the asphalt mixture can be obtained through theoretical analyses. In order to validate the concepts associated with the above mentioned tests, corresponding conventional tests have also been conducted to the same materials in the study. According to the comparisons between the conventional and the LWT tests, the LWT tests proposed in this study provided satisfactory repeatability and efficiency.

A execução de obras apoiadas em solos moles constitui um desafio para a engenharia geotécnica. Pela baixa capacidade de suporte do solo mole, tais obras estão sujeitas a sofrer colapso, geralmente por ruptura do solo de base; e recalques excessivos, que ocorrem ao longo do tempo por efeito do adensamento do solo mole. Em virtude destes problemas, quaisquer soluções que promovam o aumento da capacidade de carga do solo mole representam uma enorme contribuição ao tema. Este trabalho apresenta resultados de uma série de provas de carga realizadas em laboratório sobre uma camada de areia apoiada em solo mole. A camada de areia foi ensaiada em três condições: sem reforço, reforçada apenas por geocélulas e pela associação de geocélulas e geogrelha. Foram utilizadas geocélulas de geotêxtil com ligações costuradas e geocélulas de polietileno com ligações soldadas nas alturas de 5, 10 e 15 cm. Os resultados apontam uma melhora significativa quando do confinamento com geocélulas, tanto em termos de recalque quanto de capacidade de suporte. A utilização de geocélulas conjugadas a um reforço basal com geogrelha permitiu uma melhora do desempenho ainda mais significativa / Works resting on soft soils represent a large task to geotechnical engineers. Due to the soft soil low bearing capacity, such works might present a rotational failure or present large settlements that occurwith time due to consolidation. For these problems any technical contribution that would allow an increase fo the bearing capacity of the soft soils would represent an enormous help to geotechnical engineering. This work presents results of laboratory loading plate tests carried out on a sandy layer resting on the topo of a soft soil deposit. The sandy layer was tested in there different conditions: unreinforced, reiforced with geocells and with geocells and geogrids. Geocells made out of strips of non woven geotextile with sewed joints and made from welded joint poliethylene strips were used. The results of plate tests showed a significant improvement not only in terms of bearing capacity but also in terms of settlement reduction when geocells alonge were used. The use of geocells associated with geogrids allowed further improvements in the bearing capacity and settlement reductions

A numerical investigation was conducted to evaluate the geotechnical safety and slope stability of Municipal Solid Waste (MSW) landfills, considering the effects of geosynthetic reinforcements, biodegradation of the waste, and associated changes in material properties, and extreme wind force simulating hurricane conditions. Three different landfill slopes, 1:1, 1:2, and 1:3 having the height of 122m and width of 2134m, were analyzed using Limit Equilibrium Method (SLOPE/W) and Finite Element Modeling (ANSYS). Techniques developed in this study were used to analyze a case history involving a geogrid reinforced mixed landfill expansion located in Austria. It was found that few years after construction of the landfill, there is a significant decrease in the FS due to biodegradation. Extreme wind loading was also found to cause a substantial loss in the FS. The geosynthetic reinforcement increased the slope stability and approximately compensated for the damaging effects of biodegradation and wind loading. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

The various aspects of the 3D cellular confinement systems (geocells) subjected to static loading are comprehensively studied with the help of experimental and numerical studies. The performances of the geocells were separately studied in both sand and clay beds. Laboratory tests were performed on single as well as multiple cells. The behavior of 3D-cells made of different materials such as Novel polymeric alloy, geogrids and bamboo were compared. Moreover, the performances of the geocells were compared with other forms of geosynthetic reinforcements namely, geogrids and the combination of geocells and geogrids. In addition to comprehensive experimental study, 2-dimensional and 3-dimensional numerical modelling efforts are also presented. A Realistic approach of modelling the geocells in 3D framework has been proposed; which considers the actual curvature of the geocell pockets. An Analytical equation has been proposed to estimate the increase in the bearing capacity of the geocell reinforced soft clay beds. Similarly, a set of equations to estimate the stress and strains on the surface of the geocells subjected to compressive loading were also proposed. A case study highlighting the innovative use of the geocell foundation to support the embankment on soft settled red mud has been documented in the thesis. A new and emerging application of geocell to protect underground utilities and the buried pipelines has been proposed. At the end, behavior of the geocell under cyclic loading has also been discussed. Firstly, laboratory model tests were performed to understand the behavior of the geocells in sand and clay beds. Test results of unreinforced, geogrid reinforced, geocell reinforced, and geocell reinforced with additional planar geogrid at the base of the geocell cases were compared separately for sand and clay beds. Results revealed that the use of geocells increases the ultimate bearing capacity of the sand bed by 2.9 times and clay bed by 3.6 times. Provision of the basal geogrid increases the ultimate load carrying capacity of the sand and clay bed by about 3.6 times and 4.9 times, respectively. Besides increasing the load carrying capacity, provision of the planar geogrid at the base of the cellular mattress arrests the surface heaving and prevents the rotational failure of the footing. Geocells contribute to the load carrying capacity of the foundation bed, even at very low settlements. In addition, the effect of infill materials on the performance of the geocell was also studied. Three different infill materials, namely aggregate, sand and local red soil were used in the study. Results suggest that the performance of the geocell was not heavily influenced by the infill materials. Out of which aggregate found to be slightly better than other two infill materials. Further, 2-dimensional numerical studies using FLAC2D (Fast Lagrangian Analysis of Continua in 2D) were carried out to validate the experimental findings. The equivalent composite approach was used to model the geocells in 2-dimensional framework. The results obtained from the FLAC2D were in good agreement with the experimental results. However, in the sand bed, FLAC2D overestimated the bearing pressure by 15% to 20% at higher settlements. In addition, the joint strength and the wall deformation characteristics of the geocells were studied at the single cell level. The study helps to understand the causes for the failure of the single cell in a cellular confinement system. Experimental studies were conducted on single cells with cell pockets filled up with three different infill materials, namely, silty clay, sand and the aggregates. The results of the experimental study revealed that the deformation of the geocell wall decreases with the increase in the friction angle of the infill material. Measured strain values were found to be in the range of 0.64% to 1.34% for different infill materials corresponding to the maximum applied bearing pressure of 290 kPa. Experimental results were also validated using FLAC3D. Findings from the numerical studies were in accordance with the experimental results. A simple analytical model based on the theory of thin cylinders was also proposed to calculate the accumulated strain of the geocell wall. This model operates under a simple elastic solution framework. The proposed model slightly overestimates the strains as compared to experimental and numerical values. A realistic approach of modelling the geocells in 3-dimensional (3D) framework has been proposed. Numerical simulations have been carried out by forming the actual 3D honeycomb shape of the geocells using the finite difference package FLAC3D. Geocells were modeled using the geogrid structural element available in the FLAC 3D with the inclusion of the interface element. Geocells, foundation soil and the infill soil were modeled with the different material model to match the real case scenario. The Mohr Colombo model was used to simulate the behavior of the sand bed while modified Cam clay was used to simulate the behavior of the clay bed. It was found that the geocells distribute the load in lateral direction to a relatively shallow depth as compared to unreinforced case. More than 50% reduction in the stress in the presence of geocells and more than 70% reduction in the stress in the presence geocells with basal geogrid were observed in sand and clay beds. The numerical model was also validated with the experimental studies and the results were found to be in good agreement with each other. The validated numerical model was used to study the influence of various properties of the geocells on the performance of the reinforced foundation beds. The performance of the foundation bed was directly influenced by the modulus and the height of the geocells. Similarly, the pocket size of the geocell inversely affected the performance of the reinforced beds. The geocell with textured surface yielded better performance than the geocell with smooth surface. A case history of the construction of a 3 m high embankment on the geocell foundation over the soft settled red mud has been documented. Red mud is a waste product from the Bayer process of Aluminium industry. The reported embankment is located in Lanjigharh (Orissa) in India. The geotechnical problems of the site, the design of the geocell foundation based on experimental investigation and the construction sequences of the geocell foundations in the field are discussed. Based on the experimental studies, an analytical model was also developed to estimate the load carrying capacity of the soft clay bed reinforced with geocell and the combination of geocell and geogrid. The solution was established by superimposing the three mechanisms viz. lateral resistance effect, vertical stress dispersion effect and the membrane effect. By knowing the pressure applied on the geocell, tensile strength of the geogrid and the limiting settlement, the increment in the load carrying capacity can be calculated. The analytical model was validated with the experimental results and the results were found to be in good agreement with each other. The results of the experimental and analytical studies revealed that the use of the combination of geocell and the geogrid is always beneficial than using the geocell alone. Hence, the combination of geocell and geogrid was recommended to stabilize the embankment base in Lanjigharh. Over 15,000 mof embankment base was stabilized using geocell foundation. The foundation work was completed within 15 days using locally available labors and the equipment. Construction of the embankment on the geocell foundation has already been completed. The constructed embankment has already sustained two monsoon rains without any cracks and seepage. Like Aluminum tailings (redmud), geocell foundations can also be used in various other mine tailings like zinc, copper etc. Geocell foundation can offer potential solutions to storage problems faced by various mining industries. The thesis also proposes a potential alternative to the geocells in the form of bamboocells in order to suit the Indian scenario. Indian has the 2nd largest source of bamboo in the world. The areas particularly rich in bamboo are the North Eastern States, the Western Ghats, Chattisgarh and Andaman Nicobar Islands. The tensile strength and surface roughness of the bamboo was found to be 9 times and 3 times higher than geocell materials. In order to use the bamboo effectively, 3D cells (similar to geocells) and 2D grids (similar to geogrids) are formed using bamboo known as bamboocells and bamboogrids respectively. The idea behind forming bamboocells is to extract the additional confining effect on the encapsulated soil by virtue of its 3-dimensional shape. The laboratory investigations were performed on a clay bed reinforced with natural (bamboo) and commercial (geosynthetics) reinforcement materials. The performance of bamboocells and bamboogrids reinforced clay beds were compared with the clay bed reinforced with geocells and geogrids. The ultimate bearing capacity of the bamboocell and bamboogrid reinforced clay bed was found to be 1.3 times that of reinforced with geocell and geogrid. The settlement of the clay bed was reduced by 97% due to the insertion of the combination of the bamboocell and bamboogrid as compared to the unreinforced clay bed. The bamboo was treated chemically to increase the durability. The performance of the bamboo was reduced by 15-20% after the chemical treatment; still the performance was better than its geosynthetic counterparts. Analytical studies revealed that the 3% of the ultimate tensile strength of the bamboogrid was mobilized while resisting the footing load. The study also explored the new and innovative applications of the geocells to protect underground utilities and buried pipelines. The laboratory model tests and the numerical studies were performed on small diameter PVC pipes, buried in geocell reinforced sand beds. In addition to geocells, the efficacy of only geogrid and geocell with additional basal geogrid cases were also studied. A PVC (Poly Vinyl Chloride) pipe with external diameter 75 mm and thickness 1.4 mm was used in the experiments. The vehicle tire contact pressure was simulated by applying the pressure on the top of the bed with the help of a steel plate. Results suggest that the use of geocells with additional basal geogrid considerably reduces the deformation of the pipe as compared to other types of reinforcements. Further, the depth of placement of pipe was also varied between 1B to 2B (B is the width of loading plate) below the plate in the presence of geocell with additional basal geogrid. More than 50% reduction in the pressure and more than 40% reduction in the strain values were observed in the presence of reinforcements at different depths as compared to the unreinforced beds. Further, experimental results were validated with 3-dimensional numerical studies using 3D FLAC. Good agreement in the measured pipe stain values were observed between the experimental and numerical studies. In addition, the results of the 1-g model tests were scaled up to the prototype case of the shallow buried pipeline below the pavement using the appropriate scaling laws. The efficacy of the geocells was also studied under the action of cyclic loading. The laboratory cyclic plate load tests were performed in soft clay bed by considering the three different cases, namely, unreinforced, geocell reinforced and geocell with additional basal geogrid reinforced. The coefficient of elastic uniform compression (Cu) was evaluated from the cyclic plate load tests for the different cases. The Cu value was found to increase in the presence of geocell reinforcement. The maximum increase in the Cu value was obtained for the case of the clay bed reinforced with the combination of geocell and the geogrid. The results of the laboratory model tests were extrapolated to prototype foundation supporting the low frequency reciprocating machine. The results revealed that, in the presence of the combination of geocell and the geogrid the natural frequency of the foundation-soil system increases by 4 times and the amplitude of the vibration reduces by 92%.