Spelling suggestions: "subject:"[een] PLATE LOAD TESTS"" "subject:"[enn] PLATE LOAD TESTS""
1 |
Ensaios de placa em areia não saturada reforçada com fibras / Plate load tests on fiber-reinforced unsaturated sandsGirardello, Vinícius January 2010 (has links)
O objetivo do presente trabalho foi estudar o comportamento mecânico de uma areia não saturada, com e sem reforço de fibras, através de ensaios de placa realizados em densidade relativa de 50% e 90%. Para o reforço da areia foi acrescentada a quantidade de 0,5% de fibra de polipropileno em relação ao peso seco de solo. A análise dos resultados dos ensaios de placa indica que a inclusão de fibras influencia significativamente no comportamento carga-recalque do material. O melhor resultado foi obtido para o ensaio realizado na maior densidade relativa (DR = 90%) com adição de fibras, apresentando uma mudança significativa no comportamento carga-recalque. Ensaios triaxiais também foram realizados a fim de obter os parâmetros de resistência e deformação dos materiais estudados. Além disso, ensaios de sucção foram realizados para avaliar a sua influência sobre os parâmetros de resistência do solo não saturado, com e sem reforço. / The aim of present research was to study the mechanical behavior of unreinforced and fiber-reinforced unsaturated sand through plate load tests carried out at relative densities of 50% and 90%. For the reinforced sand, 50 mm long polypropylene fibers were added at a concentration of 0.5% by dry weight. The analysis of the plate test results indicates that the soil load-settlement behavior is significantly influenced by the fiber inclusion. The best performance was obtained for the densest (DR=90%) fiber-sand mixture, where a significant change in the load-settlement behavior was observed. Triaxial tests were also carried out in order to establish the strength and deformation parameters of the materials studied. Furthermore, suction tests were carried out to investigate its potential influence on the strength parameters of the unsaturated fiber-reinforced and unreinforced materials.
|
2 |
Ensaios de placa em areia não saturada reforçada com fibras / Plate load tests on fiber-reinforced unsaturated sandsGirardello, Vinícius January 2010 (has links)
O objetivo do presente trabalho foi estudar o comportamento mecânico de uma areia não saturada, com e sem reforço de fibras, através de ensaios de placa realizados em densidade relativa de 50% e 90%. Para o reforço da areia foi acrescentada a quantidade de 0,5% de fibra de polipropileno em relação ao peso seco de solo. A análise dos resultados dos ensaios de placa indica que a inclusão de fibras influencia significativamente no comportamento carga-recalque do material. O melhor resultado foi obtido para o ensaio realizado na maior densidade relativa (DR = 90%) com adição de fibras, apresentando uma mudança significativa no comportamento carga-recalque. Ensaios triaxiais também foram realizados a fim de obter os parâmetros de resistência e deformação dos materiais estudados. Além disso, ensaios de sucção foram realizados para avaliar a sua influência sobre os parâmetros de resistência do solo não saturado, com e sem reforço. / The aim of present research was to study the mechanical behavior of unreinforced and fiber-reinforced unsaturated sand through plate load tests carried out at relative densities of 50% and 90%. For the reinforced sand, 50 mm long polypropylene fibers were added at a concentration of 0.5% by dry weight. The analysis of the plate test results indicates that the soil load-settlement behavior is significantly influenced by the fiber inclusion. The best performance was obtained for the densest (DR=90%) fiber-sand mixture, where a significant change in the load-settlement behavior was observed. Triaxial tests were also carried out in order to establish the strength and deformation parameters of the materials studied. Furthermore, suction tests were carried out to investigate its potential influence on the strength parameters of the unsaturated fiber-reinforced and unreinforced materials.
|
3 |
Ensaios de placa em areia não saturada reforçada com fibras / Plate load tests on fiber-reinforced unsaturated sandsGirardello, Vinícius January 2010 (has links)
O objetivo do presente trabalho foi estudar o comportamento mecânico de uma areia não saturada, com e sem reforço de fibras, através de ensaios de placa realizados em densidade relativa de 50% e 90%. Para o reforço da areia foi acrescentada a quantidade de 0,5% de fibra de polipropileno em relação ao peso seco de solo. A análise dos resultados dos ensaios de placa indica que a inclusão de fibras influencia significativamente no comportamento carga-recalque do material. O melhor resultado foi obtido para o ensaio realizado na maior densidade relativa (DR = 90%) com adição de fibras, apresentando uma mudança significativa no comportamento carga-recalque. Ensaios triaxiais também foram realizados a fim de obter os parâmetros de resistência e deformação dos materiais estudados. Além disso, ensaios de sucção foram realizados para avaliar a sua influência sobre os parâmetros de resistência do solo não saturado, com e sem reforço. / The aim of present research was to study the mechanical behavior of unreinforced and fiber-reinforced unsaturated sand through plate load tests carried out at relative densities of 50% and 90%. For the reinforced sand, 50 mm long polypropylene fibers were added at a concentration of 0.5% by dry weight. The analysis of the plate test results indicates that the soil load-settlement behavior is significantly influenced by the fiber inclusion. The best performance was obtained for the densest (DR=90%) fiber-sand mixture, where a significant change in the load-settlement behavior was observed. Triaxial tests were also carried out in order to establish the strength and deformation parameters of the materials studied. Furthermore, suction tests were carried out to investigate its potential influence on the strength parameters of the unsaturated fiber-reinforced and unreinforced materials.
|
4 |
Medidas diretas de tensão em solo reforçado com fibras de polipropileno / Direct stress measurement in polypropylene fiber-reinforced soilDonato, Maciel January 2007 (has links)
Este trabalho tem como objetivo estudar a distribuição de tensões em um solo arenoso reforçado com fibras de polipropileno através de ensaios de prova de carga em placa circular, com medidas diretas de tensão pelo uso de células de tensão total. Busca-se investigar a influência da adição de fibras no comportamento carga-recalque de camadas compactadas de solo, avaliando o efeito do teor de fibras. Calibrações em laboratório foram realizadas para avaliar os fatores que afetam as medições de tensões em células de tensão total inseridas no solo. Utilizou-se também o Método dos Elementos Finitos (MEF) para simular numericamente a distribuição de tensões dentro de câmaras de calibração. Ensaios de provas de carga em placa de 0,30 m de diâmetro sobre camadas de areia compactada, reforçada e não reforçada com fibras, foram realizados, buscando a investigação do comportamento cargarecalque destas misturas, dos mecanismos de ruptura e da distribuição de tensões no interior das camadas e no contato solo/placa. A análise dos resultados mostra que a distribuição das tensões verticais na câmara de calibração é função do seu fator de forma e que as constantes de calibração também são função da posição de instalação das células de tensão. Nos ensaios de placa pode-se observar que o comportamento carga-recalque do solo arenoso é significativamente influenciado pela adição de fibras, aumentando a capacidade de suporte e alterando os mecanismos de ruptura. As medidas de tensões mostram uma mudança na distribuição de tensões com a inclusão do reforço. / The aim of this work is to study the polypropylene fiber-reinforced sand stress distribution through circular plate load tests, with direct stress measurement using total stress cells. The influence of fiber inclusion in load-settlement behavior of thick compacted soil layers was investigated and the fiber content effect evaluated. Laboratory calibrations were carried out in order to evaluate the factors that affect the stress measurements in total stress cells inserted in the soil. The Finite Element Method (FEM) was applied to simulate the numerical stress distribution inside the calibration chambers. Plate load tests with 0.30 m diameter plate bearing on compacted sand reinforced and non-reinforced layers were carried out to investigate the load-settlement behavior, failure mechanisms and stress distributions inside the sand layers and in the soil/plate contact. The analysis of the results shows that the vertical stress distribution inside the calibration chambers is a function of the high/diameter relationship and the calibration constants are a function of the stress cells installation position. It can be observed that the sand load-settlement behavior is significantly influenced by fiber inclusion, increasing bearing capacity and changing failure mechanisms. The stress measurements indicate an alteration in the stress distribution with the fiber inclusion.
|
5 |
ESTUDO DO COMPORTAMENTO DE SOLOS ATRAVÉS DE ENSAIOS DE PLACA DE DIFERENTES DIÂMETROS / STUDY ON SOIL BEHAVIOR THROUGH PLATE LOAD TESTS WITH DIFFERENT DIAMETERSRussi, Daniel 15 June 2007 (has links)
The dimensioning of shallow foundations requires the professional to define clearly and objectively, for the soil in question, the load capacity and forecast the settlings of the foundation submitted to the structure having as base its mechanical properties obtained through field and/or laboratory investigation. One of the safest ways to take this decision is based on information from plate load tests because through this it is possible to reproduce in a minor proportion the real behavior of the future foundation, perhaps using this as a tool to help in the decision making to dimension shallow foundations, contributing to a more efficient development of the foundation work. The present work is about the analysis of the CEEG/UFSM soil behavior through tests on direct load proof on foundation field (plate load test). The research is divided, basically into two great phases. There was an experimental phase which comprehended geotechnical characterization trials and plate load tests to evaluate
the behavior tension-settling of foundation. There were 7 plate load tests in 3 ditches dug manually up to 0,7 m depth. Plates with 15, 30 and 50 cm diameter were used and the reaction system was formed by reaction piles united by a reaction beam. The second phase was the analysis of the results obtained, analyzed through curves tension-settling of foundation, where some criteria were applied to define the rupture tension and some considerations were done on the settling of foundation forecast and scale effect. / O dimensionamento de fundações superficiais requer que o profissional defina de forma clara e objetiva, para o solo em questão, a capacidade de carga e a previsão dos recalques que se submete à estrutura, baseando-se em suas propriedades mecânicas obtidas em investigações de campo e/ou laboratório. Uma das formas mais seguras de se tomar essa decisão está baseada nas informações advindas do ensaio de carregamento direto sobre placas, pois, através dele, se reproduz em escala reduzida o comportamento real da futura fundação, podendo servir como ferramenta de auxílio na tomada de decisão para o dimensionamento de
fundações superficiais, contribuindo para o desenvolvimento mais eficaz das obras de fundação. O presente trabalho trata da análise do comportamento do solo do CEEG/UFSM
através do ensaio de prova de carga direta sobre terreno de fundação (ensaio de placa). A pesquisa dividiu-se basicamente em duas grandes etapas. Uma etapa experimental, a qual compreendeu ensaios de caracterização geotécnica e ensaios de placa para a avaliação do
comportamento tensão-recalque. Realizou-se 7 ensaios de placa em três trincheiras escavadas manualmente até a profundidade de 0,7 metros. Utilizou-se placas de 15, 30 e 50 cm de diâmetro e o sistema de reação compreendia estacas de reação unidas por uma viga de reação. A segunda etapa consistiu na análise dos resultados obtidos, analisados através de curvas tensão-recalque, as quais se aplicaram alguns critérios para definir a tensão de ruptura e fez-se
algumas considerações sobre a previsão de recalques e o efeito escala.
|
6 |
Medidas diretas de tensão em solo reforçado com fibras de polipropileno / Direct stress measurement in polypropylene fiber-reinforced soilDonato, Maciel January 2007 (has links)
Este trabalho tem como objetivo estudar a distribuição de tensões em um solo arenoso reforçado com fibras de polipropileno através de ensaios de prova de carga em placa circular, com medidas diretas de tensão pelo uso de células de tensão total. Busca-se investigar a influência da adição de fibras no comportamento carga-recalque de camadas compactadas de solo, avaliando o efeito do teor de fibras. Calibrações em laboratório foram realizadas para avaliar os fatores que afetam as medições de tensões em células de tensão total inseridas no solo. Utilizou-se também o Método dos Elementos Finitos (MEF) para simular numericamente a distribuição de tensões dentro de câmaras de calibração. Ensaios de provas de carga em placa de 0,30 m de diâmetro sobre camadas de areia compactada, reforçada e não reforçada com fibras, foram realizados, buscando a investigação do comportamento cargarecalque destas misturas, dos mecanismos de ruptura e da distribuição de tensões no interior das camadas e no contato solo/placa. A análise dos resultados mostra que a distribuição das tensões verticais na câmara de calibração é função do seu fator de forma e que as constantes de calibração também são função da posição de instalação das células de tensão. Nos ensaios de placa pode-se observar que o comportamento carga-recalque do solo arenoso é significativamente influenciado pela adição de fibras, aumentando a capacidade de suporte e alterando os mecanismos de ruptura. As medidas de tensões mostram uma mudança na distribuição de tensões com a inclusão do reforço. / The aim of this work is to study the polypropylene fiber-reinforced sand stress distribution through circular plate load tests, with direct stress measurement using total stress cells. The influence of fiber inclusion in load-settlement behavior of thick compacted soil layers was investigated and the fiber content effect evaluated. Laboratory calibrations were carried out in order to evaluate the factors that affect the stress measurements in total stress cells inserted in the soil. The Finite Element Method (FEM) was applied to simulate the numerical stress distribution inside the calibration chambers. Plate load tests with 0.30 m diameter plate bearing on compacted sand reinforced and non-reinforced layers were carried out to investigate the load-settlement behavior, failure mechanisms and stress distributions inside the sand layers and in the soil/plate contact. The analysis of the results shows that the vertical stress distribution inside the calibration chambers is a function of the high/diameter relationship and the calibration constants are a function of the stress cells installation position. It can be observed that the sand load-settlement behavior is significantly influenced by fiber inclusion, increasing bearing capacity and changing failure mechanisms. The stress measurements indicate an alteration in the stress distribution with the fiber inclusion.
|
7 |
Medidas diretas de tensão em solo reforçado com fibras de polipropileno / Direct stress measurement in polypropylene fiber-reinforced soilDonato, Maciel January 2007 (has links)
Este trabalho tem como objetivo estudar a distribuição de tensões em um solo arenoso reforçado com fibras de polipropileno através de ensaios de prova de carga em placa circular, com medidas diretas de tensão pelo uso de células de tensão total. Busca-se investigar a influência da adição de fibras no comportamento carga-recalque de camadas compactadas de solo, avaliando o efeito do teor de fibras. Calibrações em laboratório foram realizadas para avaliar os fatores que afetam as medições de tensões em células de tensão total inseridas no solo. Utilizou-se também o Método dos Elementos Finitos (MEF) para simular numericamente a distribuição de tensões dentro de câmaras de calibração. Ensaios de provas de carga em placa de 0,30 m de diâmetro sobre camadas de areia compactada, reforçada e não reforçada com fibras, foram realizados, buscando a investigação do comportamento cargarecalque destas misturas, dos mecanismos de ruptura e da distribuição de tensões no interior das camadas e no contato solo/placa. A análise dos resultados mostra que a distribuição das tensões verticais na câmara de calibração é função do seu fator de forma e que as constantes de calibração também são função da posição de instalação das células de tensão. Nos ensaios de placa pode-se observar que o comportamento carga-recalque do solo arenoso é significativamente influenciado pela adição de fibras, aumentando a capacidade de suporte e alterando os mecanismos de ruptura. As medidas de tensões mostram uma mudança na distribuição de tensões com a inclusão do reforço. / The aim of this work is to study the polypropylene fiber-reinforced sand stress distribution through circular plate load tests, with direct stress measurement using total stress cells. The influence of fiber inclusion in load-settlement behavior of thick compacted soil layers was investigated and the fiber content effect evaluated. Laboratory calibrations were carried out in order to evaluate the factors that affect the stress measurements in total stress cells inserted in the soil. The Finite Element Method (FEM) was applied to simulate the numerical stress distribution inside the calibration chambers. Plate load tests with 0.30 m diameter plate bearing on compacted sand reinforced and non-reinforced layers were carried out to investigate the load-settlement behavior, failure mechanisms and stress distributions inside the sand layers and in the soil/plate contact. The analysis of the results shows that the vertical stress distribution inside the calibration chambers is a function of the high/diameter relationship and the calibration constants are a function of the stress cells installation position. It can be observed that the sand load-settlement behavior is significantly influenced by fiber inclusion, increasing bearing capacity and changing failure mechanisms. The stress measurements indicate an alteration in the stress distribution with the fiber inclusion.
|
8 |
[pt] AVALIAÇÃO DO COMPORTAMENTO CARGA-RECALQUE DE UMA AREIA REFORÇADA COM FIBRAS DE COCO SUBMETIDOS A ENSAIOS DE PLACA EM VERDADEIRA GRANDEZA / [en] EVALUATION OF LOAD-SETTLEMENT BEHAVIOR OF COCONUT FIBERS REINFORCED SAND UNDER PLATE LOAD TESTS IN REAL SCALEJUAN MANUEL GIRAO SOTOMAYOR 07 October 2015 (has links)
[pt] Este estudo avaliou a influência da inclusão de fibra de coco como reforço de solo. A fibra de coco utilizada foi obtida por processo mecânico na empresa ECOFIBRA, que possui uma parceria com a Companhia de Limpeza Urbana da cidade do Rio de Janeiro (COMLURB) em projeto piloto de coleta seletiva das cascas de coco verde. Foi realizada uma comparação entre a areia pura e a areia reforçada com fibras de coco para avaliar o comportamento carga-recalque por meio de ensaios de placa em verdadeira grandeza. O objetivo é usar a fibra de coco que normalmente é descartada em grande quantidade, após o consumo do fruto. Procura-se estabelecer padrões de comportamento que possam explicar a influência da inclusão de fibras aleatoriamente distribuídas e de fibras colocadas no formato de manta entre as camadas de solo. Os ensaios foram realizados utilizando uma densidade relativa padrão de 50 por cento e um teor de umidade de 10 por cento. Foi observado nas curvas carga-recalque que o reforço de fibra em manta conseguiu uma diminuição maior do recalque, mas com um maior fissuramento superficial, enquanto que o reforço com as fibras colocadas aleatoriamente conseguiu uma menor redução dos recalques, mas uma melhor inibição da propagação de fissuras. Ambos os resultados, comparados com a areia sem adição de fibras, demostraram uma maior resistência e redução do recalque ocorrido na areia pura. Os resultados são satisfatórios para a aplicação de reforço de solo com fibras de coco em camadas de aterros sanitários e aterros sobre solos moles, dentre outros, dando um fim mais nobre para este material e obtendo-se uma solução para o problema da acumulação da fibra de coco, devido ao grande consumo existente na cidade de Rio de Janeiro. / [en] This study evaluated the influence of the inclusion of coconut fiber as reinforcement of soil. The coconut fiber used is obtained by a mechanical process in ECOFIBRA Company, which has a partnership with the Urban Cleaning Company of the city of Rio de Janeiro (COMLURB) in a pilot project about separate collection of green coconut. Sandy soil reinforced and unreinforced were compared, evaluating load-settlement behavior through real-scale plate load testing. The aim is to use the coconut fiber, discarded in large quantities after consumption of the fruit. It seeks to establish patterns of behavior that may explain the influence of the inclusion of fibers randomly (individual) and as a reinforcing mat (composed) between layers of soil. The tests were performed using as a standard, a relative density of 50 per cent and a humidity content of 10 per cent. The load-settlement curves showed a better stress distribution using fiber rug but a greater degree of surface fissuring was noted. Instead using randomization distribution, stress distribution was lower but was inhibited surface fissuring propagation; both results were compared with soil without addition of fibers increased resistance to settlement. The results are satisfactory for an application of reinforcement layers of soil in landfills and platforms over soft ground, giving a nobler end to this material, trying to give a solution to the problem of accumulation due to the large consumption existing in Rio de Janeiro city.
|
9 |
Ground Improvement using 3D-Cellular Confinement Systems : Experimental and Numerical StudiesHegde, Amarnath January 2014 (has links) (PDF)
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%.
|
Page generated in 0.0573 seconds