Geosynthetic reinforced soil (GRS) is a soil improvement technology in which closely spaced horizontal layers of geosynthetic are embedded in a soil mass to provide lateral support and increase strength. GRS is popular due to a relatively new application for bridge support, as well as long-standing application in mechanically stabilized earth walls. Several different GRS design methods have been used, and some are application-specific and not based on fundamental principles of mechanics. Because consensus regarding fundamental behavior of GRS is lacking, numerical and mathematical analyses were performed for laboratory tests obtained from the published literature of GRS under triaxial compression in consolidated-drained conditions. A three-dimensional numerical model was developed using FLAC3D. An existing constitutive model for the soil component was modified to incorporate confining pressure dependency of friction angle and dilation parameters, while retaining the constitutive model's ability to represent nonlinear stress-strain response and plastic yield. Procedures to obtain the parameter values from drained triaxial compression tests on soil specimens were developed. A method to estimate the parameter values from particle size distribution and relative compaction was also developed. The geosynthetic reinforcement was represented by two-dimensional orthotropic elements with soil-geosynthetic interfaces on each side. Comparisons between the numerical analyses and laboratory tests exhibited good agreement for strains from zero to 3% for tests with 1 to 3 layers of reinforcement. As failure is approached at larger strains, agreement was good for specimens that had 1 or 2 layers of reinforcement and soil friction angle less than 40 degrees. For other conditions, the numerical model experienced convergence problems that could not be overcome by mesh refinement or reducing the applied loading rate; however, it appears that, if convergence problems can be solved, the numerical model may provide a mechanics-based representation of GRS behavior, at least for triaxial test conditions. Three mathematical theories of GRS failure available in published literature were applied to the laboratory triaxial tests. Comparisons between the theories and the tests results demonstrated that all three theories have important limitations. These numerical and mathematical evaluations of laboratory GRS tests provided a basis for recommending further research. / Ph. D. / Sometimes soils in nature do not possess the strength characteristics necessary to be used in a specific engineering application, and soil improvement technologies are necessary. Geosynthetic reinforced soil (GRS) is a soil improvement technology in which closely spaced horizontal layers of geosynthetic material are placed in a soil mass to provide lateral support and increase the strength of the reinforced mass. The geosynthetic materials used in GRS are flexible sheets of polymeric materials produced in the form of woven fabrics or openwork grids. This technology is widely used to improve the strength of granular soil to form walls and bridge abutments. Current design methods for GRS applications are case specific, some of these methods do not rely on fundamental principles of physics, and consensus regarding the fundamental behavior of GRS is lacking. To improve understanding of GRS response independent of application, the three dimensional response of GRS specimens to axisymmetric loading were investigated using numerical and mathematical analysis. A numerical model using the finite difference method in which the domain is discretized in small zones was developed, and this model can capture the response of GRS laboratory specimens under axisymmetric loading with reasonably good accuracy at working strains (up to 3% strain). This numerical model includes a robust constitutive model for the soil that is capable of representing the most important stiffness and strength characteristics of the soil. For large strains approaching failure loading, the numerical model encountered convergence difficulties when the soil strength was high or when more than two layers of reinforcement were used. As an alternative to discretized numerical analysis, three mathematical theories available in the published literature were applied to the collected GRS laboratory test data. These evaluations demonstrated that all three theories have important limitations in their ability to represent failure of GRS laboratory test specimens. This study is important because it proposed a numerical model in 3D to represent the GRS behavior under working strains, and it identified several limitations of mathematical theories that attempt to represent the ultimate strength of GRS. Based on these findings, recommendations for further research were developed.

[pt] O presente estudo apresenta o comportamento dos solos reforçados com PET em pó e triturado, através de ensaios de laboratório. Foram utilizados três solos: um solo coluvionar, uma areia limpa e mal graduada e uma bentonita. Caracterização física, química e ensaios mecânicos (triaxiais CIU e cisalhamento direto) foram realizadas para cada material e misturas. O ensaio triaxial foi realizado em amostras de solo argiloso compactado com porcentagens de pó de PET de 0, 10, 20 e 30 por cento de PET triturado de 3,0 e 5,0 por cento, por seco peso de solo. Os ensaios triaxiais, em amostras de areia foram feitas a uma densidade relativa de 50 por cento e 10 por cento de teor de umidade, e com 0, 10 e 20 por cento de pó de PET, em relação ao peso seco do solo. Os ensaios de cisalhamento direto com bentonita foram feitos com porcentagens de 0 e 30 por cento de pó de PET e 3,0 e 5,0 por cento de PET triturado, por peso seco de solo. Os resultados mostraram que o teor de PET e nível de confinamento têm influência sobre o comportamento mecânico final das misturas. Com ambos os resíduos de PET, as misturas apresentam um comportamento satisfatório, aumentando ou mantendo os parâmetros de resistência ao cisalhamento semelhantes ao solo puro. Assim, para as misturas argilosos, a mistura com 30 por cento de pó de PET e a com 5 por cento de PET triturado são mais eficazes, uma vez que nelas observou-se maior melhora nos parâmetros de resistência. Para misturas de areia a inclusão PET é mais eficaz com 10 por cento de pó PET em tensões confinantes menores e umidade ótima de 10 por cento. Para misturas bentonita, a inserção de PET é mais eficaz para o PET triturado na porcentagem de 5 por cento. Portanto, o uso de resíduos de PET para o reforço do solo poderia minimizar os problemas atuais disposição do resíduo, contribuir com a redução do consumo de recursos naturais e dar um uso nobre para este material. / [en] This study presents the behavior of soils reinforced with crushed PET (Polyethylene Terephthalate) residue through experimental study. Three soils were used: a coluvionar soil, a clean and poorly graduated sand and a bentonite. Physical characterization, chemical and mechanical tests (isotropically consolidated-drained triaxial and direct shear) were performed for each material and mixtures. The triaxial test was performed on samples of clayey soil compacted within the maximum dry density and optimum moisture content with ratios of 0, 10, 20 and 30 per cent of fine crushed PET and 3,0 and 5,0 per cent of PET flakes, by dry weight of soil. The triaxial tests on sand samples were made to a relative density of 50 percent and 10 per cent of water content, and with 0, 10 and 20 percent fine crushed PET, by dry weight of soil. The direct shear tests with bentonite were made with ratios of 0 and 30 percent of fine crushed PET and 3,0 and 5,0 percent of PET flakes, by dry weight of soil. The results have shown that the PET content and level of confining stress have influence on the final mechanical behavior of the mixtures. With both residue of PET, the mixtures present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure soil. Thus, for the clayey mixtures, the fine crushed PET content of 30 percent and the PET flakes content of 5 percent are more effective, once they increase the strength parameters. For sandy mixtures the PET inclusions is more effective with 10 percent of fine crushed PET at lower confining stresses and the optimum content is 10 percent. For bentonite mixtures the PET inclusions is more effective for PET flakes and the optimum content is 5. Therefore, the use of PET waste for soil reinforcement could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.

[pt] Este estudo apresenta o comportamento de solos reforçados com adição de pérolas de EPS (Poliestireno Expandido) através de estudo experimental. Os solos utilizados foram: um solo argiloso de origem coluvionar, uma areia limpa, mal graduada e bentonita. Foram realizados ensaios de caracterização física e de caracterização mecânica, como ensaios de compactação Proctor Normal, ensaios triaxiais consolidados isotropicamente drenados (CID) e ensaios de cisalhamento direto para buscar estabelecer padrões de comportamento que possam explicar a influência da adição de pérolas de EPS, relacionando-a com os parâmetros de resistência ao cisalhamento. Os ensaios triaxiais CID foram realizados em amostras de solo argiloso compactadas na densidade máxima seca e umidade ótima, com teores de pérolas de EPS de 0 por cento, 0,25 por cento, 0,50 por cento, 0,75 por cento e 1 por cento, em relação ao peso seco do solo e os ensaios triaxiais CID em amostras de areia foram realizados para uma densidade relativa de 50 por cento e umidade de 10 por cento, com teores de pérolas de EPS de 0 por cento, 0,50 por cento e 0,75 por cento, em relação ao peso seco do solo. Os ensaios de cisalhamento direto com bentonita foram realizados com teores de pérolas de EPS de 0 por cento, 0,50 por cento e 0,75 por cento, em relação ao peso seco do solo. Os resultados mostraram que o tipo de solo, o teor de pérolas de EPS e o nível de tensão confinante influenciam positivamente o comportamento mecânico final dos compósitos com relação aos parâmetros de resistência, porém não há uma tendência de comportamento bem definida ao analisar cada fator independentemente. Portanto, o uso de pérolas de EPS em obras geotécnicas de carregamento estático contribuiria com o menor consumo de material natural e a consequente redução dos custos de transporte e volume de material mobilizado. / [en] This study presents the behavior of soils reinforced with EPS (Expanded Polystyrene) beads through experimental study. The soils used were a coluvionar soil, a clean and barely graduated sand and bentonite. Physical characterization, Standard Proctor, consolidated drained triaxial and direct shear tests were performed to establish patterns of behavior that may explain the influence of the addition of expanded polystyrene beads, linking it with shear strength parameters. The CID triaxial was performed on samples of clayey soil compacted within the maximum dry density and optimum moisture content with expanded polystyrene beads ratios of 0 percent, 0.25 percent, 0.50 percent, 0.75 percent and 1 percent by dry weight of soil. CID triaxial tests on sand samples were made to a relative density of 50 per cent and 10 per cent of moisture content, with EPS beads ratios of 0 percent, 0.50 percent and 0.75 percent by dry weight of soil. The direct shear tests with bentonite were made with EPS beads ratios of 0 percent, 0.50 percent and 0.75 percent by dry weight of soil. The results showed that the kind of soil, the EPS content and level of confining stress level influence positively on the final mechanical behavior of the composites with respect to strength parameters, but there is no well-defined pattern of behavior to examine each factor independently. Therefore, the use of EPS beads in geotechnical works, contribute to lower consumption of natural material and the consequent reduction in transport costs and volume of mobilized material.

Design of retaining structures depends upon the load which is transferred from backfill soil as well as external loads and also the resisting capacity of the structure. The traditional safety factor approach of the design of retaining structures does not address the variability of soils and loads. The properties of backfill soil are inherently variable and influence the design decisions considerably. A rational procedure for the design of retaining structures needs to explicitly consider variability, as they may cause significant changes in the performance and stability assessment. Reliability based design enables identification and separation of different variabilities in loading and resistance and recommends reliability indices to ensure the margin of safety based on probability theory. Detailed studies in this area are limited and the work presented in the dissertation on the Optimum design of retaining structures under static and seismic conditions: A reliability based approach is an attempt in this direction. This thesis contains ten chapters including Chapter 1 which provides a general introduction regarding the contents of the thesis and Chapter 2 presents a detailed review of literature regarding static and seismic design of retaining structures and highlights the importance of consideration of variability in the optimum design and leads to scope of the investigation. Targeted stability is formulated as optimization problem in the framework of target reliability based design optimization (TRBDO) and presented in Chapter 3. In Chapter 4, TRBDO approach for cantilever sheet pile walls and anchored cantilever sheet pile walls penetrating sandy and clayey soils is developed. Design penetration depth and section modulus for the various anchor pulls are obtained considering the failure criteria (rotational, sliding, and flexural failure modes) as well as variability in the back fill soil properties, soil-steel pile interface friction angle, depth of the water table, total depth of embedment, yield strength of steel, section modulus of sheet pile and anchor pull. The stability of reinforced concrete gravity, cantilever and L-shaped retaining walls in static conditions is examined in the context of reliability based design optimization and results are presented in Chapter 5 considering failure modes viz. overturning, sliding, eccentricity, bearing, shear and moment failures in the base slab and stem of wall. Optimum wall proportions are proposed for different coefficients of variation of friction angle of the backfill soil and cohesion of the foundation soil corresponding to different values of component as well as lower bounds of system reliability indices. Chapter 6 presents an approach to obtain seismic passive resistance behind gravity walls using composite curved rupture surface considering limit equilibrium method of analysis with the pseudo-dynamic approach. The study is extended to obtain the rotational and sliding displacements of gravity retaining walls under passive condition when subjected to sinusoidal nature of earthquake loading. Chapter 7 focuses on the reliability based design of gravity retaining wall when subjected to passive condition during earthquakes. Reliability analysis is performed for two modes of failure namely rotation of the wall about its heel and sliding of the wall on its base are considering variabilities associated with characteristics of earthquake ground motions, geometric proportions of wall, backfill soil and foundation soil properties. The studies reported in Chapter 8 and Chapter 9 present a method to evaluate reliability for external as well as internal stability of reinforced soil structures (RSS) using reliability based design optimization in the framework of pseudo static and pseudo dynamic methods respectively. The optimum length of reinforcement needed to maintain the stability against four modes of failure (sliding, overturning, eccentricity and bearing) by taking into account the variabilities associated with the properties of reinforced backfill, retained backfill, foundation soil, tensile strength and length of the geosynthetic reinforcement by targeting various component and system reliability indices is computed. Finally, Chapter 10 contains the important conclusions, along with scope for further work in the area. It is hoped that the methodology and conclusions presented in this study will be beneficial to the geotechnical engineering community in particular and society as a whole.

The EC Landfill Directive (1999), which is enforced in England and Wales through the Landfill (England and Wales) Regulations (2002), has increased the technical challenge associated with the design and construction of landfill containment systems, in particular those on steep side slopes. Increased numbers of lining system components, varied configurations, and complex loading scenarios require advanced analysis tools to facilitate design. This project involved the development of advanced numerical modelling techniques, based on the FLAC finite difference modelling code. The analysis toolbox can be used to predict the behaviour of multilayered geosynthetic and soil lining systems, during and after staged construction. The model can include non-linear interface and geosynthetic axial properties, represent complex loading, including downdrag from the waste mass, whilst retaining the flexibility to represent varied geometries and include engineered support structures. Whilst numerical modelling is becoming increasingly commonplace in commercial design, there is little evidence of the validation of numerical models with field or experimental data. Validation of the analysis toolbox described in this document was conducted by back analysis of published data, modelling of landfill failure mechanisms, and comparisons to large scale laboratory testing. Design of field scale instrumentation has also been carried out as part of this project. The influence of interface shear strength variability has been assessed through the compilation of a comprehensive database, and the effect of this variability on lining system behaviour assessed through reliability based analyses. This has shown probability of failures may be higher than proposed limiting values when adopting traditional accepted factors of safety. A key area of interest identified during the project was the requirement for support, potentially through reinforcement, of the geological barrier. The inclusion of randomly reinforced fibres in bentonite enhanced soil has shown the potential for increased strength, without adverse effects on hydraulic barrier performance. ii Additionally, the influence of geomembrane seams on lining system integrity has been investigated, showing that fusion welded seams can result in stress concentration and extruded seams can cause significant stress concentration.

[pt] O presente trabalho tem como objetivo a implementação e avaliação de um modelo constitutivo para solos reforçados com fibra (compósito). A principal característica do modelo constitutivo implementado é que cada material (matriz de solo e fibra) segue sua própria lei constitutiva e ao mesmo tempo interagem entre si. Utilizando um algoritmo explícito, são implementados os modelos Cam Clay Modificado e Lade-Kim para a matriz de solo, cuja verificação é feita mediante o programa PLAXIS 2D e curvas tensão-deformação obtidas da literatura, respectivamente. Posteriormente, é adicionado o comportamento da fibra no desenvolvimento das tensões no compósito e verificado mediante a comparação das curvas tensão-deformação com as apresentadas por Diambra et al. (2013). As linguagens de programação utilizadas neste trabalho foram duas, a primeira é a utilizada no programa MATLAB, onde os códigos dos modelos são verificados e validados em relação à um conjunto de ensaios triaxiais de areia reforçada com fibra. Posteriormente foi usada a linguagem de programação FORTRAN para incluir o modelo constitutivo para solo reforçado com fibras no programa de elementos finitos ABAQUS, através da sub-rotina UMAT. Porém, para a implementação na sub-rotina UMAT os códigos dos modelos implementados no MATLAB sofrem algumas modificações com a finalidade de que o ABAQUS consiga compilar e representar adequadamento o comportamento do modelo constitutivo, mediante a correta utilização de vetores e propriedades desta. Finalmente, são modelados ensaios triaxiais drenados para verificar que a implementação mediante a sub-rotina UMAT é satisfatória. / [en] The present work aims to implement and evaluate a constitutive model for fiber-reinforced soils (composite). The main characteristic of the constitutive model implemented is that each material (soil and fiber matrix) follows its own constitutive law and at the same time interact with each other. Using an explicit algorithm, the Cam Clay Modified and Lade-Kim models are implemented for the soil matrix, verified by the PLAXIS 2D software and stress-strain curves obtained from the literature, respectively. Later, it is included the behavior of the fiber in the development of the stresses in the composite and verified by the comparison of the stress-strain curves with those presented by Diambra et al. (2013). The programming languages used in this work were two, the first one is the one used in the MATLAB program, where the codes of the models are verified and validated in relation to a set of triaxial tests of fiber-reinforced sands. Later the programming language was converted into FORTRAN to include the constitutive model for fiber reinforced soil in the ABAQUS finite element software, through the UMAT subroutine. However, for the implementation in the UMAT subroutine the codes of the models implemented in MATLAB undergo some modifications in order that ABAQUS can compile and represent adequately the behavior of the constitutive model through the correct use of vectors and its properties. Finally, drained triaxial tests are modeled to verify that the implementation through the UMAT subroutine is satisfactory.

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%.