Dissertations / Theses on the topic 'Subgrade soils'
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1
Sekulovic, Dejan. "Identification of modulus of subgrade reaction of soils at pile/soil interface." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/MQ52659.pdf.
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Orman, Marc Elliot 1958. "A study of bedding intrustion into low strength subgrade." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558102.
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Han, Zhong. "Modelling Stiffness and Shear Strength of Compacted Subgrade Soils." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35059.
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Compacted soils are frequently used as subgrade for pavements as well as commercial and residential buildings. The stiffness and shear strength properties of compacted soils, which are collectively denoted as Ω in this thesis, fluctuate with moisture content changes that result from the influence of environmental factors such as the evaporation and infiltration. For example, mechanistic pavement design methods require the information of resilient modulus (MR), which is the soil stiffness behavior under cyclic traffic loading, and its variation with respect to the soil moisture content determined from laboratory tests or estimation methods. Significant advances have been made during the last five decades to understand and model the variation of the Ω with respect to soil moisture content and soil suction (s) based on the principles of mechanics of unsaturated soils. There are a variety of models presently available in the literature relating the Ω to the s using different approaches. There are however uncertainties extending these models for predicting Ω - s relationships when they are used for a larger soil suction range. In addition, the good performance of these models are only valid for certain soil types for which they were developed and calibrated.
Studies presented in this thesis are directed towards developing a unified methodology for modelling the relationship between the Ω and the s using limited while easy-to-obtain information. However, more emphasis has been focused on the MR - s relationships of pavement subgrade soils considering the need for the application of the mechanistic pavement design methods in Canada. The following studies have been conducted:
(i) State-of-the-art review on existing equations in the literature for the MR - s relationships is summarized. A comparison study is followed to discuss the strengths and limitations of these equations;
(ii) A unified methodology for modelling the Ω - s relationships is proposed. Experimental data on 25 different soils are used to verify the proposed unified methodology. The investigations are applied on small strain shear modulus, elastic modulus, and peak and critical shear strength. Good predictions are achieved for all of the investigated soils;
(iii) Performance of the proposed methodology is examined for the MR - s relationships using experimental data of 11 subgrade soils. Reasonably good predictions are achieved for all of the subgrade soils;
(iv) Extensive experimental investigations are conducted on the MR - s relationships for several subgrade soils collected from various regions in Canada. Experimental results suggest non-linear variation in the MR with respect to s, moisture content and the external stress. The measured results are modelled using the proposed methodology with adequate success;
(v) Additional experimental investigations are performed to determine the variation of the elastic modulus (E) and unconfined compression strength (qu) with the s and the gravimetric moisture content (w) for several Canadian subgrade soils. An approach, which is developed extending the proposed unified methodology, is used to normalize the measured MR - w, E - w and qu - w relationships. It is shown that the normalized MR - w, E - w and qu - w relationships exhibit remarkable similarity and can be well described using the proposed approach. Such similarity in the normalized Ω - moisture content relationships are also corroborated using the experimental data on several other soils reported in the literature.
The proposed unified methodology alleviates the need for the determination of the Ω - s relationships which requires elaborate testing equipment that needs the supervision of trained personnel and is also time-consuming and expensive. In addition, experimental programs in this thesis provide detailed experimental data on the MR, E, qu, and soil-water characteristic curves of Canadian subgrade soils. These data will be helpful for the better understanding of the hydro-mechanical behavior of the Canadian subgrade soils and for the implementation of the mechanistic pavement design method in Canada. The simple tools presented in this thesis are promising and encouraging for implementing the mechanics of unsaturated soils into conventional geotechnical engineering practice.
4
Mao, Baimin. "Predicting resilient modulus of highway subgrade soils in Ohio." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179257407.
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Parker, John Wesley. "Evaluation of Laboratory Durability Tests for Stabilized Subgrade Soils." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2393.pdf.
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Lee, Jangguen. "The Behavior of Pore Water Pressure in Cohesive Subgrade Soils." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1364216774.
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Ouf, Mohamed El-Sadek Abdel Rahman. "Stabilisation of clay subgrade soils using ground granulated blastfurnace slag." Thesis, University of Leeds, 2001. http://etheses.whiterose.ac.uk/327/.
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Roads constructed on expansive clays may be adversely affected by the behaviour of the clay. Expansive clays suffer volume change due to changes in moisture content which causes heaving, cracking and the break up of the road pavement. Stabilisation of these types of soil is necessary to suppress swelling and increase the strength of the soil and thus partially decrease the thickness of road pavement layers. The use of by-product materials for stabilisation has environmental and economic benefits. Ground granulated blastfurnace slag (GGBS), a by-product material in Egypt, and lime are used in the current work to stabilise samples of a clay soil similar to a typical Egyptian clay soil. This test soil comprises 80% River Aire soil and 20% calcium montmorillonite. The main objectives of this research were to investigate the effect of GGBS, with and without lime, on the engineering behaviour (plasticity characteristics, compaction, unconfined compressive strength (UCS) and swelling potential) of the test soil and to identify the reaction products of the stabilised materials to determine the mechanisms by which changes in engineering properties are obtained. In order to achieve these objectives, extensive laboratory investigations were carried out. Various mixes (up to 10% GGBS by dry weight of the test soil and up to 30% replacement by hydrated lime) were prepared and cured under two representative conditions {20°C with 90-100% relative humidity (CCI) and 35° C with 50-60% relative humidity (CC2)} for up to 12 months. Compaction and plasticity were measured soon after mixing, the swelling potential and UCS were measured after longer curing periods. Four analytical techniques {X ray diffraction, scanning electron microscopy, differential thermal analysis and nuclear magnetic resonance (NMR)} were used to identify the reaction products of the clay fraction of the test soil mixed with various amount of GGBS and lime. This pure clay test soil was used to ease identification of the reaction products. The investigations showed that generally the engineering properties (UCS, swelling, plasticity) improved with the addition of GGBS and with increasing curing period and temperature. The addition of lime resulted in a dramatic improvement within the test ranges covered in the programme. The maximum dry density, MDD, decreased and the optimum moisture content, OMC, increased with increasing GGBS and lime content. The major changes in the UCS and swelling behaviour are due to the formation of new cementitious materials. The analytical investigation confirmed two major reactions when GGBS and lime were added to the pure clay soil, hydration of GGBS activated by lime to produce calcium aluminosilicate hydrate gel (C-A-S-H) and hydrotalcite type phase, and the clay-lime reaction to produce calcium silicate hydrate (C-S-H), (C-A-H) and (C-A-S-H). The NMR test results revealed that the aluminosilicate chain length (EL), the aluminium: silicate (Al/Si) ratio and the amount of Si in the formed C-S-H significantly increased with an increase in the curing temperature and period, which indicates a more stable and well crystalline C-S-H. The results indicate that the use of GGBS alone, or preferably with lime, could have a significant effect on the behaviour of potentially swelling clays. Recommendations for further studies include a study of the effect of cyclic loading on the test soil. Also, site trials should be carried out to assess the suitability of using these materials in the field.
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Rasul, Jabar. "Investigating the use of stabilized subgrade soils for road pavements in Kurdistan." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6819/.
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Road pavement design in Kurdistan is based on ASSHTO 1993. However, it seems not to be entirely satisfactory since it is unable to take full account of properties of local soils or those which have been stabilised. To address this, a design procedure applicable to different material and environmental conditions was developed. The associated research consisted of a suite of laboratory experiment allied to the development of a finite element model. The laboratory work was undertaken on three types of subgrade soils found in Kurdistan to determine their permanent deformation behaviour, UCS and resilient modulus for a range of moisture contents. The experimental investigation considered soils stabilised with 2%, 4% cement content and a combination of cement and lime with 2% cement plus 1.5% lime and 4% cement and 1.5% lime. The results were used to develop empirical equations to: (i) predict resilient modulus values of deteriorated modified soils as a function of different stabiliser contents and types; (ii) correlate resilient modulus values of soils with their UCS and stress state; (iii) determine the accumulation of permanent deformation in modified subgrade soils subject to weathering. These relationships, together with the developed finite element model were used to establish the design procedure.
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Kim, Dong-Gyou. "Engineering properties affecting the resilient modulus of fine-grained soils as subgrade." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1298905282.
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Ika, Putra Agus. "Stabilisation of expansive subgrade soils with slag and cement for road construction." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/374.
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This research evaluates stabilisation of expansive soil as a subgrade for road pavement. The recommended stabiliser proportion was 13.5% slag + 1.5% cement at 28 days curing time, which based on obtaining UCS test results that eight times magnitudes higher than the strength of the non-stabilised soil. The CBR values were more than four times higher than the minimum required for designing road pavement. The best resilient modulus correlation model was the hyperbolic correlation model.
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Davies, Beresford O. A. "A model for the prediction of subgrade soil resilient modulus for flexible-pavement design : influence of moisture content and climate change /." See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1102690606.
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Thesis (M.S.V.)--University of Toledo, 2004.Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Civil Engineering." Bibliography: leaves 80-83.
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Kim, Dong-Gyou. "Development of a constitutive model for resilient modulus of cohesive soils." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078246971.
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Gu, Huanda. "Environmental Geotechnical Approach on the Application of Ferrum-Series Lime Stabilized Soils to Road Base and Subgrade." Kyoto University, 1998. http://hdl.handle.net/2433/182351.
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Vizcarra, S., S. Vizcarra, I. Lujan, M. Soto, and G. Durán. "Experimental analysis of the addition of rice husk ash to the clayey subgrade of a road stabilized with lime." Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/651791.
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There are many studies about how the addition of lime and rice husk ash (RHA) gives the soil a better mechanical behavior, particularly on clayey soils, where usually fine particles reach more than 75%. However, the soils with a small presence of fine particles (59-60%) do not have much research. This analysis evaluates the influence that RHA has on this kind of soil stabilized with 3% of lime. After the initial mix of soil-lime, CBR increased 11.2 times its initial value; within the addition of the ash, the CBR averaged between 45-50% up until 28% of RHA was added, where the results decreased considerably. Soil workability improved and the specimens with more ash resulted in a more granular material, with a group index value 0 following the AASHTO standards. The greatest CBR record was obtained with the specimen of 16% RHA, 3% lime and soil, reaching a 51.3% CBR, 1.58g/cm3 of MDD and 16.5% of OMC. Yet, it only showed a 1.55% more resistance than the lime-soil specimen. The CBR with more presence of RHA tends to decrease its value, therefore for silica-rich clayey soils, the addition of lime by itself should be enough for an adequate performance.
15
Saarenketo, T. (Timo). "Electrical properties of road materials and subgrade soils and the use of Ground Penetrating Radar in traffic infrastructure surveys." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514282221.
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This PhD thesis is composed of a synopsis and five published papers that are focused on both the research results of studies on electrical properties of road materials and subgrade soils and their seasonal changes and the use of Ground Penetrating Radar technique in traffic infrastructure surveys. The data for this survey was collected mainly in Finland, Texas, Scotland and Sweden and thus presents many kinds of road materials, subgrade soils and climate conditions.
The synopsis of this work begins with a presentation of the theory and basic principles of GPR techniques. Special attention is given to the dielectric properties and seasonal changes of unbound road materials and subgrade soils. The synopsis also presents different kinds of GPR hardware systems as well as recommendations and experiences from different data collection, processing and interpretation techniques. Special attention is given to a method whereby GPR data is integrated with other road survey data and then analysed using a number of structural diagnostic methods. Finally, the synopsis provides an overview of of the various GPR applications on roads and streets, bridges, railways and airports.
The laboratory test results presented in this work show that the relationship between dielectric value and increasing water content is not linear or exponential but more likely a series of logarithmic functions. Laboratory results also showed that dielectric dispersion, which can be related to poorly performing subgrade soils and road aggregates, takes place mainly in loosely bound adsorption water and capillary water layer. As such these moisture sensitive problem materials can also be identified during the dry summer seasons when they are stiff. Dielectric value and electrical conductivity can also be related to other technical properties of road materials and subgrade soils such as frost susceptibility, shear strength, plastic limit, compaction degree and voids content. Laboratory tests and field data collected using the Percostation technique also demonstrate that a knowledge of seasonal changes and thermodynamics is very important in understanding and modelling the mechanical behaviour of road structures. Finally, laboratory and field tests indicate that colloids have an important role in the failure mechanism of the road materials.
This research demonstrates that the GPR technique not only gives valuable structural information on the different types of structures and subgrade soils but it provides a wide range of information of the electrical properties of the materials under survey which can be further related to their mechanical performance. The best information will be gained if GPR data is analysed together with other non destructive testing data collected form the roads, railways and airports.
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Cekinmez, Zeynep. "Effect Of Foundation Rigidity On Contact Stress Distribution In Soils With Variable Strength / Deformation Properties." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611478/index.pdf.
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In this study, a typical mat foundation and structural loading pattern is considered. Three dimensional finite element analyses, PLAXIS 3D, is performed to determine the soil / foundation contact stress distribution, settlement distribution, distribution of modulus of subgrade reaction as a function of column spacing, stiffness of the soil and thickness of the foundation. A parametric study is performed to demonstrate the dependence of those distributions on various parameters. Moreover, a relationship between size of the foundation, deformation modulus of foundation soil and modulus of subgrade reaction is proposed. Depending on the variations in those parameters, obtained shear force and bending moment distributions are compared. Consistency between the resulting shear forces and bending moments of a typical foundation, modeled in two different three dimensional finite element programs, PLAXIS 3D and SAP 2000, is discussed.
It is found that the variation in the aforementioned parameters cause different influences on contact stress distribution, settlement distribution, distribution of modulus of subgrade reaction. The importance of those variations in beforementioned parameters, under different situations is discussed. A relationship between modulus of subgrade reaction and deformation modulus of foundation soil is proposed.
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Dong, K., D. P. Connolly, O. Laghrouche, P. K. Woodward, and Costa P. Alves. "The stiffening of soft soils on railway lines." Elsevier, 2018. https://publish.fid-move.qucosa.de/id/qucosa%3A73234.
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Railway tracks experience elevated rail deflections when the supporting soil is soft and/or the train speed is greater than approximately 50% of the wave propagation velocity in the track-soil system (i.e. the critical velocity). Such vibrations are undesirable, so soil replacement or soil improvement of the natural soil (or alternatively mini-piles or lime-cement treatment) is often used to increase track-ground stiffness prior to line construction. Although areas of existing soft subgrade might be easily identified on a potential new rail route, it is challenging to determine the type and depth of ground remediation required. Therefore, major cost savings can be made by optimising ground replacement/improvement strategies.
This paper presents a numerical railway model, designed for the dynamic analysis of track-ground vibrations induced by high speed rail lines. The model simulates the ground using a thin-layer finite element formulation capable of calculating 3D stresses and strains within the soil during train vehicle passage. The railroad track is modelled using a multi-layered formulation which permits wave propagation in the longitudinal direction, and is coupled with the soil model in the frequency-wavenumber domain. The model is validated using a combination of experimental railway field data, published numerical data and a commercial finite element package. It is shown to predict track and ground behaviour accurately for a range of train speeds.
The railway simulation model is computationally efficient and able to quickly assess dynamic, multi-layered soil response in the presence of ballast and slab track structures. Therefore it is well-suited to analysing the effect of different soil replacement strategies on dynamic track behaviour, which is particularly important when close to critical speed. To show this, three soil-embankment examples are used to compare the effect of different combinations of stiffness improvement (stiffness magnitude and remediation depths up to 5 m) on track behaviour. It is found that improvement strategies must be carefully chosen depending upon the track type and existing subgrade layering configuration. Under certain circumstances, soil improvement can have a negligible effect, or possibly even result in elevated track vibration, which may increase long-term settlement. However, large benefits are possible, and if detailed analysis is performed, it is possible to minimise soil improvement depth with respect to construction cost.
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Ferreira, Carla de Castro. "Aspectos do coeficiente de recalque de solos da formação Guabirotuba." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-02032016-141913/.
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Este trabalho parte de um acervo pré-existente de provas de carga em placa (segundo os procedimentos ABNT-NBR-6489 e ASTM-D-1196) em solos da Formação Guabirotuba, importante unidade geológica da região metropolitana de Curitiba. O objetivo do trabalho é favorecer o entendimento destes solos no que diz respeito à sua competência como subleito para pavimentos industriais rígidos. É realizada uma revisão sobre modelos de fundação de pavimento, aspectos geológicos e geotécnicos da Formação Guabirotuba, e métodos de determinação do coeficiente de recalque. A análise baseia-se no coeficiente de recalque \"k\" obtido em trinta e duas provas de carga em placa e utiliza uma classificação prática dos solos, quanto ao seu nível de intemperismo: argilas cinzas \"inalteradas\", argilas vermelhas \"laterizadas\" e argilas variegadas \"intemperizadas\", as quais mostram valores decrescentes de coeficiente de recalque, nessa ordem. Notou-se que algumas correlações existentes na literatura permitiram obter razoáveis previsões do coeficiente de recalque, como aquelas baseadas em valores de SPT e de CBR. Os valores de coeficiente de recalque medidos para estes solos mostram-se superiores àqueles sugeridos por tabelas práticas. Devido à variabilidade de resultados encontrada e à influência do subleito no desempenho final do sistema de fundação, fica evidenciada a importância da realização de provas de carga em placa para obtenção dos parâmetros de dimensionamento de pavimentos industriais rígidos.The present work employs a data base of plate load tests (performed according the ABNT-NBR-6489 and ASTM-D-1196 procedures) in soils of the Guabirotuba Formation, important geological unit of Curitiba metropolitan region. The purpose of the work is the improving of the knowledge of these soils related to their behavior as subgrade for rigid industrial pavements. It is provided a revision about pavements foundation models, geological and geotechnical aspects of the Guabirotuba Formation and methods of the determination of the modulus of subgrade reaction. The analysis is based on the modulus of subgrade reaction \"k\" from 32 plate loading tests and uses a practical classification of the soils, according to their weathering level: intact gray clays, lateritic red clays and weathered variagate clays that showed a derease of the modulus in this order. Some correlations were found to predict fair values of \"k\", such as those based on SPT and on DCP. It was also noticed that the values of the modulus of subgrade reaction obtained are higher than the usual recommendations of the literature. The variability and the influence of the subgrade in the final performance of the pavaments make evident the importance of the plate load tests for obtaining reliable design parameters.
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Khasawneh, Mohammad Ali. "LABORATORY CHARACTERIZATION OF COHESIVE SUBGRADE MATERIALS." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1124387175.
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Gomes, Adriana Cristina. "Monitoramento de uma estrutura de contenção em estacas espaçadas considerando perfil de sucção." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5404.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This study presents the results of an extensive field monitoring program in which the lateral displacements of a nail reinforced sheet pile wall in Goiânia, Brazil were measured during the excavation process. The instrumentation methods adopted were multiple point borehole extensometers (MPBX) and optical surveying. The MPBX showed good results that could be appropriately interpreted as the excavation progressed. However, the measurements of optical surveying were not reliable due the low precision of total station and for being highly affected by user’s errors. In order to determine the geotechnical profile, laboratory test were undertaken to obtain strength and deformation parameters for unsaturated and saturated soil conditions. The large variability of the soil, observed in terms of void ratio, presented an important obstacle, making the determination of representative shear strength parameters a challenge. As a way to bridge the analysis of field monitoring results, soil properties and the numerical back analyses of the retaining walls, the water content profile and the soil-water characteristic curve were measured. Such data was used to obtain the suction profile and evaluated its influence in the monitored field data. Finally, the numerical code Sheeting Check (Geo5), which uses the beam on elastic foundation method, was employed to obtain the soil subgrade reaction modulus (ks) and determine the retaining wall deformation profile and earth pressures in saturated and unsaturated soil condition. The maximum lateral displacements values found in the numerical back analyses were compatible with the monitoring results. Besides, the influence of unsaturated soil conditions and soil suction in the reduction of the retaining wall deformations and the active earth pressures were observed.
Este estudo apresenta resultados de um extenso monitoramento de deslocamentos horizontais de uma estrutura de contenção em estacas espaçadas com tirantes passivos na cidade de Goiânia, Brasil que foram medidas durante o processo de escavação. Os métodos de instrumentação adotados foram de extensômetros de hastes horizontais múltiplas (EHHM) e medições topográficas. O EHHM apresentou bons resultados que permitiu interpretar corretamente o progresso da escavação. Todavia, as medições topográficas não foram confiáveis devido à baixa precisão da Estação Total e sendo bastante afetados por erros do usuário. Para determinar o perfil geotécnico do solo, ensaios em laboratório foram realizados para obter parâmetros de resistência e deformabilidade para o solo na condição natural e saturada. A grande variabilidade do solo, observada em termos de índice de vazios, se apresenta como importante obstáculo, tornando a determinação representativa dos parâmetros de resistência ao cisalhamento um desafio. Buscando acoplar as análises dos resultados de monitoramento em campo, propriedades do solo e retro análises da estrutura de contenção, o perfil de umidade e a curva característica solo-água foram medidos. Esses dados foram utilizados para obter o perfil de sucção do solo e avaliar sua influência nos dados monitorados em campo. Por fim, a ferramenta numérica Shetting Check (Geo5), que aplica o método de viga apoiada sobre base elástica, foi utilizada para obter o módulo de reação do solo (ks) e avaliar o comportamento do perfil de deformação da parede de contenção e do empuxo de terra para o solo na condição saturada e não saturado. Os valores de deslocamentos horizontais máximos obtidos a partir da retro análise apresentam-se compatíveis com valores da literatura. Além disso, a influência da sucção na redução da deformação da parede de contenção e dos empuxos ativos foi observada.
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Veisi, Maryam. "Accelerated mix design of stabilized subgrades." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Glatz, Thomas. "The electro-osmotic acceleration of infiltration into the subgrade of pavements." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16326.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The moisture content of road foundations plays an important role in the durability of the pavement and the driving comfort of the road. After a pavement has been completed, gradual moisture changes occur in the foundations until equilibrium conditions can be reached, and this can have negative results if expansive clays, for example, are present in the foundation. Pre-wetting of the foundation material is seen as a method to minimilize moisture changes after construction, but if the pavement was already completed, it would be very difficult to change or alter the moisture content in the foundation, because water could then only be applied to the shoulder areas of the road and horizontal infiltration in the soil is exceptionally slow. The research which is reported in this account was undertaken to determine whether the process of electro-osmosis could be applied to accelerate water infiltration underneath covered areas, as in, for example, road foundation layers. Electro-osmosis, if found to be successful, has various advantages, of which the most important is that it can be applied without stopping the normal operations of the road. This research was carried out on a mixture of G5 material (TRH14 classification) and fine material in the form of clay with a low plasticity. Firstly, tests were performed to determine the percentage of fines required. It was found that, if too little fines were present infiltration did not occur, because moisture could flow freely through the openings between the rough aggregate. Electro-osmosis also had no effect on the rate of flow. The allocated amount of fines required to fill sufficient openings was about 30% (TRH14 classification of mixture is G10). Free flow was stopped and true infiltration occurred. Simultaneously, the rate of infiltration could be accelerated with electro-osmosis. Furthermore, a two-dimensional model of a road was constructed with electrodes placed on both sides, with the aim to determine the infiltration pattern controlled by electro-osmosis and what the effect of the initial moisture content would be on the process. Water was introduced to the one side of the model road and the wetting of the foundation was investigated. If the electric current for electro-osmosis was switched off, the infiltration was mainly vertical, as expected, but with the current switched on, there was an obvious acceleration of infiltration in the horizontal direction. As in the case of the initial tests, it was found that electro-osmosis was not very successful to accelerate horizontal infiltration at low percentages of fines. Furthermore, it was obvious that electroosmosis was also more effective if the initial moisture content of the soil was low. Low amounts of fines and high initial moisture contents had rather the electroosmotic flow of water passing underneath the road as a result instead of infiltration acceleration, with the result that the moisture content did not change much. The research thus showed that electro-osmosis is a possible manner in which moisture could be conducted into the foundation layers of roads to increase the moisture content if the appropriate amount of fines and moisture content were present in the foundation material. Further research could still be carried out and the materials in each case should be practically evaluated before this method could be continued with.
AFRIKAANSE OPSOMMING: Die voginhoud van padfondamente speel ’n belangrike rol in die duursaamheid van die plaveisel en die rygerief van die pad. Nadat ’n plaveisel voltooi is, vind daar geleidelike vogverandering in die fondamente plaas totdat ewewigstoestande bereik is, en dit kan nadelige gevolge inhou indien uitsettende kleie byvoorbeeld in die fundament teenwoordig is. Voorafbenatting van die fondamentmateriaal word gereken as ’n metode om vogveranderinge na konstruksie te minimeer, maar indien die plaveisel reeds voltooi is, is dit baie moeilik om die voginhoud in die fondament te verander of beheer omdat water dan slegs buite die skouerareas van die pad toegedien kan word en horisontale infiltrasie in grond uiters stadig is. Die navorsing waaroor hierin verslag gedoen word, is onderneem om te bepaal of die proses van elektro-osmose aangewend kan word om waterinfiltrasie onder bedekte areas, soos byvoorbeeld padfondamentlae, te versnel. Elektro-osmose, indien dit suksesvol blyk te wees, hou verskeie voordele in, waarvan die belangrikste dat dit aangewend kan word sonder om die normale bedryf van die pad te staak. Die ondersoek is uitgevoer op ’n mengsel van G5 materiaal (TRH14 klassifikasie) en fynstof in die vorm van klei met ’n lae plastisiteit. Eerstens is toetse uitgevoer om die persentasie fynstof wat nodig is, te bepaal. Daar is bevind dat, indien te min fynstof teenwoordig is, infiltrasie nie plaasvind nie aangesien water vryelik deur die openinge tussen die growwe aggregaat kan vloei. Elektro-osmose het ook geen effek op die vloeitempo gehad nie. Die aangewese hoeveelheid fynstof om genoegsame openinge te vul was ongeveer 30% (TRH14 klassifikasie van mengsel is G10). Vrye vloei is dan gestuit en ware infiltrasie het plaasgevind. Terselfdertyd kon die tempo van infiltrasie versnel word met elektro-osmose. Voorts is ’n twee-dimensionele model van ’n pad gebou, met elektrodes aan weerskante geplaas, met die doel om te bepaal of die infiltrasiepatroon deur elektro-osmose beheer kon word en wat die effek van beginvoginhoud op die proses sal wees. Water is aan een kant van die modelpad ingevoer en die benatting van die fondament bestudeer. Indien die elektriese stroom vir elektroosmose afgeskakel was, was die infiltrasie hoofsaaklik vertikaal, soos verwag, maar met die stroom aangeskakel was daar duidelike versnelling van infiltrasie in die horisontale rigting. Net soos in die geval van die aanvanklike toetse is bevind dat elektro-osmose nie baie suksesvol was om horisontale infiltrasie te versnel by lae persentasies fynstof nie. Dit het verder geblyk dat elektro-osmose ook meer effektief was indien die aanvanklike voginhoud van die grond laag was. Lae hoeveelhede fynstof en hoë aanvanklike voginhoude het eerder elektroosmotiese deurvloei van water onderdeur die pad tot gevolg gehad as infiltrasieversnelling, met die gevolg dat die voginhoud nie veel verander het nie. Die navorsing het dus getoon dat elektro-osmose ’n moontlike wyse is waarop water in die fondamentlae van paaie ingevoer kan word om die voginhoud te verhoog indien die geskikte hoeveelheid fynstof en voginhoud in die fondamentmateriaal teenwoordig is. Verdere navorsing kan nog uitgevoer word en die materiale van elke geval sal prakties evalueer moet word voordat met die metode voortgegaan kan word.
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Freese, Kevin M. "Assessment of Sulfate in Ohio Transportation Subgrades." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404393723.
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Loh, Beng Heng. "Behaviour of railway track subgrade under cyclic loading." Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/2100.
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The railway track foundation of fine-grained soil subgrade, under repeated loading of cyclic nature, can gradually build up excess pore pressure and result in progressive shear failure at a stress level much lower than the monotonic loading strength of the soil. It is widely accepted that a threshold stress exists, above which, the induced stress generates large shear deformation and; below which, the soil deformation become stabilized irrespective of the number of loading applications. Previous studies into the behaviour of fine-grained subgrade under cyclic loading had mainly involved slow loading rate. The advance in transportation technology and the required efficiency of transporting goods and commuting passengers demands higher train speed and heavier loads. Consequently, better understanding on the behaviour of fine-grained subgrade under higher rate of loading (i.e. cyclic frequency) will be necessary as it influences the build-up of excess pore water pressure and strain accumulation of subgrade soil, hence the stability of the railway track. In addition, current design approaches to the railway tracks foundation of fine-grained subgrade have largely been empirical or semi-empirical unique to a range of geological characteristic, operating and traffic condition. The rationalization and reformulation of design approach may be required if general design means will to be devised.In this research, an in-depth study of undrained triaxial testing on the behaviour of a typical fine-grained reconstituted kaolinite clay soil, simulating the characteristic subgrade responses exhibit under the passing axles / wheel load of the contemporary train speed was performed and discussed. Four series of both static and cyclic undrained triaxial test were conducted. The static undrained triaxial test provides the behavioural benchmark and a prior indication on the maximum stress level from which the cyclic stress level can be apportioned. The cyclic undrained triaxial test simulates the behaviour of clay subgrade under a large number of passing axles/wheel load. The results of the testing described and characterized the stress / strain behaviour for saturated kaolinite clay of various consolidated state and stress history. In particular, it described the general concept of cyclic stress equilibrium state and resilient state, and detailed the characteristic pattern of the line of cyclic stress equilibrium state which dictates the way in identifying the threshold stress (or critical level of cyclic stress). The study demonstrated that, using effective stress analysis, the threshold stress can be obtained for clay under high cyclic loading rate. In conjunction with the stress response, the deformation and resilient characteristics of various series of cyclic undrained triaxial tests carried out on the saturated clay was described. Apart from highlighting and confirming the influence of consolidated state and stress history on the threshold stress and deformation characteristics, influence of the cyclic loading frequency simulating higher train travelling speed was also investigated and examined.Using the framework of critical state soil mechanics, the study described the existence of cyclic stress equilibrium state surface CSESS within the stress state boundary surface SSBS for saturated clay under cyclic undrained compression. A form of analytical / theoretical model was established which enables threshold stress to be ascertained without resort to lengthy laboratory testing at the preliminary design stage of railway track foundation design. Developed from the “original Cam-clay” model and validated by the cyclic triaxial test data on reconstituted kaolin clay, the theoretical model which described the CSESS enables the prediction of threshold stress (or critical level of cyclic stress) of general saturated clay soil under undrained cyclic compression to be made from the fundamental properties of the soil, based on the designed consolidated state and the stress history of subgrade soil.In addition, this study proposed a new approach which rationalized and reformulated the current state of design and management process of railway track substructure involved clay subgrade. The rational approach was developed based on the comprehension of “lower-bound threshold stress” and potential strengthening and densification of fine-grained subgrade soil through progressive and deliberate incremental loading of the track foundation. Concept of “Managing current lower-bound threshold stress” for clay subgrade was elaborated. The readily use of the developed theoretical model and design charts for predicting the threshold stress could offer a key advantage for the new approach over current practices.
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Geiman, Christopher Matthew. "Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32499.
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Many pavement subgrades in Virginia consist of wet, highly plastic clay or other troublesome soils. Such soils can be treated with traditional lime and cement stabilization methods. Alternatives, including lignosulfonates and polymers, are available, but their performance record is mixed and solid engineering data is lacking, which prevents reliable design. The goal of this research was to screen a suite of traditional and non-traditional stabilizers against three Virginia soils that have caused problems during construction or resulted in poor performance in service. The selected stabilizers were: quicklime, hydrated lime, pelletized lime, cement, lignosulfonate, synthetic polymer, magnesium chloride, and a proprietary cementitious stabilizer. A laboratory procedure was developed and applied to three Virginia soils obtained from Northern Virginia, Staunton, and Lynchburg.
Key findings from the research include that (1) traditional lime and cement stabilizers were far more effective than liquid stabilizers (lignosulfonate, synthetic polymer, and magnesium chloride) in increasing strength, (2) the liquid stabilizers were ineffective on soils with high moisture content, (3) the proprietary cementitious stabilizer was more effective in increasing strength than lime for all cases tested, but not was not as effective as the cement stabilizer, (4) quicklime and hydrated lime increased workability of the soils although they did not produce strengths comparable to cement, (5) the strength of soils stabilized with cement and the proprietary cementitious stabilizer can be estimated based on the water-amendment ratio of the mixture, and (6) the strength of soils stabilized with lime can be estimated based on a combination of plasticity index and water-amendment ratio of the mixture.Master of Science
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Yassin, Hendro. "The behaviour of beams and slabs with soffit projections supported by uniform subgrades." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278708.
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Hidalgo, F., F. Hidalgo, J. Saavedra, C. Fernandez, and G. Duran. "Stabilization of clayey soil for subgrade using rice husk ash (RHA) and sugarcane bagasse ash (SCBA)." Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/651798.
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This document studies the stabilization of the soil used as a subgrade, by adding locally available materials such as rice husk ash (RHA) and sugarcane bagasse ash (SCBA). These aggregates were added to the soil in substitution by weight between 5%, 7.5% and 10%. By adding these, the expansiveness is reduced while the maximum dry density increases, in addition the tendency of CBR is increasing and then tends to decrease proportionally to the addition of the aforementioned aggregates. This indicates a peak in CBR and expandability. The best result obtained from CBR was 33.75% with the 5% replacement mixtures.
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Švarcová, Monika. "Dvoufázový systém stabilizace podloží vozovek." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392147.
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This diploma thesis is focused on the properties of unsuitable and conditionally unsuitable fine-grained soils after a one-stage or two-stage treatment by using a binder. The theoretical part occupies with problematical properties of the fine grained soils in a subgrade and a possible technology of the change of these properties. The laboratory testing of treated soils is described and a practical technology of the one stage and two-stage stabilization. In the practical part the fine grained soils are treated by one-stage or two-stage stabilization. For the one stage stabilization the cement is used, for the two-stage stabilization the properties of the soil are improved by lime and then the soil is stabilized by cement. The treated soils are laboratory tested, the initial bearing index IBI, California bearing ratio CBR, unconfined compressive strength and frost susceptibility is tested. Based on the results of the laboratory tests the benefit of the two-stage stabilization is measured.
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Al-Jhayyish, Anwer K. "Incorporating Chemical Stabilization of the Subgrade in Pavement Design andConstruction Practices." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1405480246.
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Lorenc, Daniel. "Namrzavost upravených zemin v podloží vozovky." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372244.
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This diploma thesis deals with the issue of the effect of freezing on soils in subgrades of road structures. The theoretical part compares methods of determining the frost susceptibility of soils used in selected countries of the European Union and the Czech Republic. It also explains the principle of frost heave in subgrade layers. The aim of the practical part is to compare the direct and indirect method of determining frost susceptibility in the Czech Republic and the California bearing ration CBR or the immediate bearing ratio IBI.
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Mohn, Douglas M. "Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216.
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DAVIES, BERESFORD OBAFEMI ARNOLD. "A MODEL FOR THE PREDICTION OF SUBGRADE SOIL RESILIENT MODULUS FOR FLEXIBLE-PAVEMENT DESIGN: INFLUENCE OF MOISTURE CONTENT AND CLIMATE CHANGE." University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1102690606.
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Kennedy, Kalub S. "Evaluation of Chemically Stabilized Subgrades with High Sulfate Concentrations." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1554807825765069.
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Castro, M., M. Castro, J. Navarro, G. Aybar, and G. Duran. "Analysis of high plasticity clayey soil improvement at subgrade level through Portland cement added to decrease volumetric change." Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/651763.
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This research includes the potential for resistance and the expansion that the soil presents, this evaluation was carried out through CBR tests. The soil cement technique was used to improve the physical and mechanical characteristics; this process consists in mixing the material with Portland cement type I. That combination forms soil cement 10%, 15% y 20%, which present an increase of the CBR (max: 138.7% and min: 91.9%) achieving a type of extraordinary subgrade to resist the structure of the pavement and a reduction of 7.18% in the expansion of the samples.
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Barnes, Glen James. "An experimental investigation on the properties and performance of geogrid and geocomposite as subgrade reinforcement in granular pavements." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/129219/2/Glen%20Barnes%20Thesis.pdf.
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This experimental study focuses on developing a new laboratory testing model that expedites the performance verification process for future geosynthetic products, for use in foundation stabilisation. Through a series of tensile and pullout tests on geosynthetic and CBR tests on geosynthetic reinforced subgrade using a bespoke CBR mould, this research highlights the benefits of including geosynthetics in granular pavement design. Further research will allow future road pavement designs in Australia to include geosynthetics as part of design specifications and reduce the environmental impact of pavement construction by minimising the required subbase layer thickness without compromising on foundation strength.
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Khoueiry, Nicole. "Study of granular platforms behaviour over soft subgrade reinforced by geosynthetics : Experimental and numerical approaches." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI027.
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Les géosynthétiques sont utilisés depuis les années 70 dans le renforcement des plateformes granulaires reposant sur des sols de faible portance pour des applications de routes non revêtues. La complexité des mécanismes développés et la diversité des produits de renforcement nécessitent encore d’étudier ces plateformes renforcées. Un essai au laboratoire permettant de tester des plateformes à échelle réelle a été développé. Une plateforme granulaire non revêtue reposant sur un sol de faible portance a été reproduite. Un protocole de mise en place de ce sol a été élaboré pour assurer son homogénéité et la répétabilité des essais. Une instrumentation spécifique a été développée pour collecter le maximum de mesures utiles pour l’interprétation du transfert de charge et du comportement des géogrilles utilisées. Trois types de géogrille ont été testées : une géogrille extrudée et deux géogrilles tricotées de rigidité différente. Après de nombreux essais de faisabilité, dix essais ont été effectués sous un chargement cyclique sur plaque circulaire, la plateforme testée a été placée dans un banc d’essai de 1,8 m de large, 1,9 m de long et 1,1 m de haut. Sur la base du même protocole de mise en œuvre, des essais de circulation avec un Simulateur Accélérateur de Traffic (SAT) ont été effectués. Ce simulateur a été spécifiquement conçu et construit pour cette application. Pour ces essais, la plateforme testée a été placée dans le banc d’essai allongé à 5 m. La plateforme a été soumise à deux types de sollicitations : un chargement cyclique sur plaque et un chargement de circulation. Des essais de répétabilité ont permis de vérifier le protocole mis en place. A partir des essais, plusieurs observations ont pu être faites sur le comportement des plateformes granulaires, le sol peu porteur, et sur l’efficacité du renforcement. De plus, ces essais ont permis de montrer que le chargement de circulation est beaucoup plus endommageant que le chargement sur plaque. Parallèlement à ces essais, un modèle numérique a été développé en se basant sur la méthode des différences finies avec le logiciel FLAC 3D. Cette modélisation a permis de prédire le comportement de la plateforme sous le premier chargement de plaqueGeosynthetics were used since 1970 in the base course reinforcement supported by soft subgrade in unpaved road application. The various factors and parameters influencing the dominant mechanism and its relative contribution on the platform improvement explain the need of more investigations in this topic. In this research work, large-scale laboratory test was developed to study the reinforcement contribution in the unpaved road improvement. Therefore, an unpaved platform was built of 600 mm of artificial subgrade supporting a base course layer. A detailed experimental Protocol was established regarding the soil preparation, the installation and the soils compaction procedure to reproduce the site conditions and insure the platform repeatability for each test. Three geosynthetics were tested first under a cyclic plate load test. Cyclic load was performed on the prepared platform, with a maximum load of 40 kN resulting in a maximum applied pressure of 560 kPa. The platform was subjected to 10,000 cycles with a frequency of 0.77 Hz. An advanced and complete soil instrumentation was provided in order to collect the maximum data needed for thorough analysis. Quality control tests were performed before each test to verify the soil layers homogeneity and properties. Two base course thicknesses were tested under this test condition, 350 and 220 mm. Once the developed protocol was confirmed under the circular plate load tests, further tests using the Simulator Accelerator of Traffic (SAT) were performed. Indeed, the laboratory prepared platform was placed in a larger box of 1.8 m in large, 5 m in length and 1.1 m in height. The prepared platform was subjected to two solicitations: a particular plate and traffic load. The Simulator Accelerator of Traffic was developed specially for this application. A machine that simulates the traffic load under an effective length of 2 m and a velocity of 4 km/h. The two areas were instrumented: the area under the circulation load, and the area under the plat load, located aside. In addition, a numerical model based on the differential element method using FLAC 3D was developed. The model simulated the circular plate load test with the same platform configuration under monotonic load. The results were compared to the first monotonic load applied on the rigid plate experimentally
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Roshani, Atena. "Road infrastructure vulnerability to groundwater table variation due to sea level rise." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/74509/1/Atena_Roshani_Thesis.pdf.
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This study was conducted to assess the vulnerability of coastal road infrastructures due to climate change induced sea level rise and extreme weather conditions through the estimation of road subgrade strength reduction as a result of changes in soil moisture content. The study area located in the Gold Coast, Australia highlighted that the risk is significant. In wet seasons or areas with wet condition, the groundwater table is already high, so even a small change in the groundwater table can raise the risk of inundation; particularly, in areas with existing shallow groundwater. The predicted risk of a high groundwater table on road infrastructure is a long-term hazard. Therefore, there is time to undertake some management plans to decrease the possible risks, for instance, some deep root plants could be planted along the roads with a high level of risk, to decrease the groundwater table elevation.
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Berti, Carolina. "Avaliação da capacidade de suporte de solos "in situ" em obras viarias atraves do Cone de Penetração Dinamica : estudo experimental." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258212.
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Orientador: Cassio Eduardo Lima de PaivaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-06T16:48:11Z (GMT). No. of bitstreams: 1 Berti_Carolina_M.pdf: 4127695 bytes, checksum: f8e52fd73231b7c47f0a12b5c7e759cc (MD5) Previous issue date: 2005
Resumo: Esta pesquisa procurou estabelecer uma correlação entre os valores de capacidade de suporte resultantes dos ensaios CBR (Califórnia Bearing Ratio) versus DCP (Dynamic Cone Penetrometer), realizados com o solo proveniente de vias não-pavimentadas dentro do Campus da UNICAMP, situado em Campinas, São Paulo. O Cone de Penetração Dinâmica (DCP) é caracterizado como um equipamento simples, portátil e de baixo custo, cujo ensaio revela ser praticamente não-destrutivo. Com ele é possível determinar o perfil de resistência de camadas de solo compactadas ou em seu estado natural, controlar a execução de obras viárias e avaliar estruturas de pavimentos. Uma investigação do solo através de ensaios DCP e CBR conduziu ao desenvolvimento de modelos de regressão, correlacionando a capacidade de suporte obtida através de ensaios ¿in situ¿ com o auxílio do DCP, e ensaios de laboratório utilizando o ensaio de CBR e DCP. Através das informações contidas na literatura técnica, dos procedimentos experimentais efetuados e das análises de regressão realizadas, ficou evidenciado o relacionamento entre o DCP e o CBR, validando as correlações estabelecidas e propondo modelos próprios, aumentando a confiabilidade dos resultados dos ensaios DCP para avaliação da capacidade de suporte de solos
Abstract: This research establishes a correlation among the strength or supporting values of the tests: CBR (California Bearing Ratio) versus DCP (Dynamic Cone Penetrometer), accomplished with the soil originating from no-paved roads inside of the Campus of UNICAMP. The Cone of Dynamic Penetration (DCP) it is characterized as an equipment simple, portable and of low cost, whose tests reveals to be practically no-destructive. DCP test determines the profile of resistance of soil layers compacted or in your natural state, to control the execution of road buildings and to evaluate structures of pavements. An investigation of the soil through DCP and CBR tests led to the development of regression models, correlating the strength measures obtained through in-situ tests with the aid of DCP and laboratory tests using the CBR and DCP. Through the information contained in the technical literature, of the made experimental procedures and of the regression analyses accomplished, the relationship was evidenced between DCP and CBR, validating the established correlations and proposing own models, increasing the reliability of the results of the DCP tests for determining strength values of soils
Mestrado
Transportes
Mestre em Engenharia Civil
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Mokeddem, Abdelhammid. "Modélisation géomécanique et probabiliste des rideaux de palplanches : prise en compte de l’interaction sol-structure et de la variabilité spatiale du sol." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0057/document.
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Le comportement géomécanique des ouvrages géotechniques à l’exemple des rideaux de palplanches est entaché d’incertitudes épistémiques liées aux hypothèses régissant le modèle géomécanique de calcul, mais aussi d’incertitudes aléatoires liées à la variabilité spatiale du sol. L’objectif principal de cette thèse est de mieux appréhender l’effet de ces incertitudes sur le comportement d’un rideau de palplanches. Pour cela le présent mémoire s’articule autour de quatre points principaux : Le premier point est relatif d’une part à l’analyse des hypothèses utilisées pour la modélisation géomécanique d’un rideau de palplanches et d’autre part à l’extension de la méthode des coefficients de réaction d’un système unidimensionnel basé sur une poutre et des appuis élastoplastiques à un système bidimensionnel de plaque orthotrope sur le même type d’appuis (MISS-CR-PLQ). Le deuxième point concerne la modélisation de la variabilité spatiale du sol. Après une comparaison entre deux méthodes de génération de champs aléatoires nous avons retenu la méthode Circulant Embedding pour son efficience. Plusieurs études paramétriques ont été menées pour analyser les effets des hypothèses prises lors de la génération des champs aléatoires. Le troisième point concerne la mise en place d’une démarche mécano-fiabiliste permettant d’intégrer la variabilité spatiale du sol pour le cas des rideaux de palplanches. Le quatrième point est consacré à l’application de la démarche développée pour un cas d’étude à travers des analyses probabilistes et fiabilistes. L’influence des paramètres statistiques (e.g. les longueurs de corrélations, la corrélation croisée, …), mécanique et géométrique a été étudiéeThe geomechanical behaviour of geotechnical structures such as sheet pile walls is subjected to epistemic uncertainties due to geomechanical models’ assumptions and also the aleatory uncertainties which could be related to the soil spatial variability. The main objective of this thesis is to gain more insight into the effect of these uncertainties on the sheet pile behaviour. To this end, this thesis focuses on four main issues: The first one is related on the one hand to the analysis of the used geomechanical hypotheses for modelling of retaining walls. On the other hand, to extend the one-dimensional subgrade reaction method which is based on a beam relying on elastoplastic supports to a two-dimensional system that call to an orthotropic plate relying on the same supports (MISS-CR-PLQ). The second issue concerns the soil spatial variability modelling. After a key comparison between two random field generation methods, we selected the Circulating Embedding method for its efficiency. Several parametric studies have been conducted to analyse the effects of different assumptions of random field generation. The third issue is related to the implementation of the proposed mechanical-reliability approach taking into account the soil spatial variability. The last issue is devoted to the application of the developed approach to a case study through probabilistic and reliability analyses. The influence of statistical parameters (e.g. correlation lengths, cross-correlation,...), mechanical and geometrical has been examined
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Umlauf, Jiří. "Návrh zajištění stavební jámy hloubeného úseku tunelu na vysokorychlostní trati Brno-Přerov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409753.
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In first part of the thesis are proposed four variants of retaining structures for deep excavation of cut-and-cover tunnel part. It is nailed slope, pile wall, nailed slope in combination with pile wall and soldier pile wall. For those structures is in following part carried out an economic analysis and the most cost effective variant is chosen. Chosen structure is further analyzed in next part. This analysis is carried out with finite element method in software PLAXIS. As a material model is chosen Hardening Soil model and input parameters were determined by empiric formulas from literature. Behavior of neogene clays, in which is the structure designed, is considered as undrained, by type Undrained A. In the last part of the thesis is described technological procedure of construction this retaining structure.
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Salour, Farhad. "Moisture Influence on Structural Behaviour of Pavements : Field and Laboratory Investigations." Doctoral thesis, KTH, Väg- och banteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162076.
Full textAbstract:
The structural behaviour of pavements in cold regions can considerably be affected by seasonal variation in environmental factors such as temperature and moisture content. Along with the destructive effect of heavy traffic loads, climatic and environmental factors can considerably contribute to pavement deterioration. These factors can influence the structural and functional capacity of the pavement structures which, as a result, can trigger and accelerate pavement deterioration mechanisms. Studies on the influence of variation of the environmental factors on the response and behaviour of pavement materials have shown that proper consideration to these factors must be given in realistic pavement design and analysis. In flexible pavement structures, particularly with a thin hot mix asphalt (HMA) layer, unbound materials and subgrade soil largely contribute to the overall structural behaviour of the pavement system. In unbound materials, moisture content and its variation can significantly affect pavement layer stiffness and permanent deformation characteristics. Therefore, the moisture condition of pavements and its influence on the mechanical behaviour of pavement materials has been of interest among the pavement research community. A proper understanding of moisture transformation in pavement systems and its effects on pavement performance are important for mechanistic pavement design. The present summary of this doctoral thesis is based on four main parts. The first part of the thesis covers field measurements and findings from a test section along county road 126 in southern Sweden and consists of two journal papers (paper I and II) tackling different aspects of the research topic. This test section is located in a relatively wet ground condition and consists of a thin flexible pavement structure with a deep drainage system. It is instrumented with subsurface temperature, volumetric moisture content and groundwater probes. The mechanical response of the pavement structure was investigated using Falling Weight Deflectometer (FWD) measurements. The second part of the thesis (paper III and IV) are based on laboratory experiments and investigates different recent approaches that have been proposed to apply principles of unsaturated soil mechanics for incorporating seasonal variation of moisture content into the resilient modulus models using matric suction. The third part of the thesis (paper V) builds a bridge that spans between the laboratory and field investigations with an attempt to evaluate one of the predictive models presented in Paper III. The fourth part of the thesis (paper VI) mainly focuses on the laboratory-based investigation of the permanent deformation characteristic of subgrade soils. In this part, the permanent deformation characteristics of two different silty sand subgrade soils were investigated and modelled using the data obtained from repeated load traxial tests. Paper I mainly focuses on the spring-thaw weakening of the pavement structure. The environmental data collected using different sensors and the FWD tests were used to investigate variations in moisture content with thaw penetration and its influence on the stiffness of unbound layers and the pavement’s overall bearing capacity. Using the backcalculated layer stiffness and corresponding in situ moisture measurements in the unbound layers, a degree of saturation-based moisture-stiffness model was developed for the granular material and the subgrade. In Paper II, the drainage system of the structure was manually clogged during a three month period in summer to raise the groundwater level and increase the moisture content of the layers. Along with the subsurface groundwater level and moisture content monitoring, the structural response of the pavement was studied. In this research work, the FWD tests were conducted at three different load levels. The stress dependent behaviour of the unbound granular layer and the subgrade soil were further studied using the multilevel loads FWD test data. Additionally, parameters of a nonlinear stress-dependent stiffness model were backcalculated and their sensitivity to in situ moisture content was studied. In Paper III and IV, series of suction-controlled repeated load triaxial (RLT) tests were conducted on two silty sand (SM) subgrade materials. Several resilient modulus prediction models that account for seasonal moisture content variation through matric suction were summarized and after optimizing the model parameters, the capability of the prediction models in capturing the material response were evaluated. In Paper V, an attempt was made to evaluate the proficiency of one of the suction-resilient modulus models using the field moisture content and FWD measurements from the Torpsbruk test site. The backcalculated subgrade stiffness dataset at different moisture contents were compared with resilient modulus models obtained from the suction-resilient modulus predictive model. Paper VI presents an evaluation of several permanent deformation models for unbound pavement materials that incorporate the time-hardening concept using a series of multistage repeated load triaxial (RLT) tests conducted on silty sand subgrade materials. The permanent deformation tests were conducted at four different moisture contents with pore suctions measurement throughout the test. The effect of moisture content (matric suction) on the permanent deformation characteristics of the materials and the predictive model parameters were further investigated.QC 20150324
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Sokolová, Veronika. "Namrzavost zemin a druhotných materiálů v podloží vozovek." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227447.
Full textAbstract:
Destruction of road constructions due to the frost is in locations with temperatures under the zero a problem which leads to permanent deformation. The theoretical part of this thesis deals with the freezing process of the pavement and its subgrade. It presents methods for determining the rate of frost susceptibility in both the Czech Republic and abroad. Describes the materials used in the subgrade of roads and their suitability in terms of frost susceptibility. The thesis closely examines the fly-ashes, their properties and possibilities of using in the construction industry. The practical part of the thesis focuses on the performance of direct laboratory frost heave tests, immediate bearing index tests, California bearing ratio tests and cyclic load triaxial tests to determine the modulus of elasticity. Tests are carried out on the soil, the soil mixtures with certain percentages of fly ash from different sources at the same soil treated with lime. Then the results are compared and dependence between the measured characteristics of materials is created.
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Mašek, Jakub. "Namrzavost zemin a materiálů v podloží vozovek." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226039.
Full textAbstract:
This diploma thesis deals with the issue of the determination of the frost susceptibility of soils in the subgrades of road structures. The theoretical part compares the ways of testing the frost susceptibility in the Czech Republic and other selected countries of the European Union. Furthermore, it also deals with the development of the frost susceptibility index in the Czech Republic. The empirical part focuses on the laboratory testing of the frost susceptibility of the given sample of soil by the direct frost heave method. Moreover, it also deals with the simulation of penetration of frost by the subgrade and the possibility of shortening the length of the freezing during the direct testing the frost susceptibility.
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Imanzadeh, Saber. "Effets des incertitudes et de la variabilité spatiale des propriétés des sols et des structures sur le dimensionnement des semelles filantes et des conduites enterrées." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00803563.
Full textAbstract:
Le sol présente une variabilité spatiale des propriétés physiques et mécaniques dont les effets sur des structures légères avec semelles filantes et sur les conduites enterrées ne sont pas bien pris en compte dans leur dimensionnement. Cette variabilité naturelle peut être très importante dans le cas de ces ouvrages car elle induit des tassements différentiels, dont les conséquences peuvent être dommageables : fissures dans les murs, les poutres ou encore des fuites dans les réseaux d'assainissement. La variabilité naturelle du sol et l'incertitude liée à la connaissance imparfaite des propriétés du sol et/ou du béton ou de l'acier de la structure sont les principales sources d'incertitude dans le choix des paramètres de calcul pour le dimensionnement de ces structures. Dans cette thèse, une approche analytique avec les méthodes probabilistes (FOSM et SOSM) et le modèle de Winkler, puis numérique avec le couplage de la méthode des éléments finis avec des approches géostatistiques ont été successivement menées pour modéliser le comportement des semelles filantes et des conduites enterrés lorsque les incertitudes sur les propriétés mécaniques du sol et de la structure sont prises en compte dans leur dimensionnement. Il apparait ainsi, l'importance du comportement longitudinal de ces ouvrages et du poids des incertitudes dans leur dimensionnement.
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Lin, Jian-Liang, and 林建良. "Resilient Modulus of Unsaturated Cohesive Subgrade Soils." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64692912006177736861.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
93
Subgrade often lies above the groundwater level and appear in unsaturated conditions. Its function is to bear the weight transfered down from the pavement. The subgrade can be affected by the seasonal rainfall or the detrimental road drainage system. As a result, water content of the subgrade may increase and the matric suction of the soils may decrease at the same time .The resilient modulus will be reduced because the increase of the water content. The axis-translation technique is used to control the soil suction and the water content state after road serving in order to investigate the relation between suction and the resilient modulus. This research used the MTS cyclic triaxial test system to carry out the resilient modulus tests on subgrade soils. The test results show that the main factor influencing the matric suction of subgrade, except the water content increase induced by the seasonal rainfall, is the deviator stress. The deviator stress loaded repeatedly may result in pore water pressure rises and then matric suction decreases. Test results also show that when the matric suction is relatively close to Equilibrium Moisture Content (EMC), the resilient modulus will increase with the increased matric suction.
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Acosta, Hector A. "Stabilization of soft subgrade soils using fly ash." 2002. http://catalog.hathitrust.org/api/volumes/oclc/50873191.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 120-125).
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Yang, Shu-Rong, and 楊樹榮. "Behavior of unsaturated subgrade soils under repeated loading." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/13284393083991916139.
Full textAbstract:
博士國立中央大學
土木工程研究所
93
Construction specifications generally require that subgrade soils be compacted in the field at or near optimum moisture content (OMC). As such, subgrade soils should be treated as unsaturated soils. Soil suction is a fundamental physical property of unsaturated soils, since soil suction dictates the state of stress in unsaturated soils. It was known resilient modulus model is a function of stress state. Hence, this study developed a resilient model based on deviator stress and matric suction. This study was undertaken to evaluate the variations of soil suction with the moisture content for two soils. In particular, the effects of compaction energy on soil suction were investigated. The matric suctions were determined by the filter paper method on soil specimens after the resilient modulus test. Findings from these tests indicated that soil suction of compacted soil is influenced by the compaction energy and water content. Soil suction increases with decreasing water content. However, high compaction energy does not necessarily lead to high soil suction. Test results demonstrated that resilient modulus correlates better with the matric suction than with total suction. Matirc suction was found to be a key parameter when predicting the resilient modulus of cohesive subgrade soils. Also, a prediction model incorporating deviator stress and matric suction for subgrade soil resilient modulus, called the deviator stress-matric suction model was established. Based on the response of subgrade soil under repeated loading tests, a critical stress level can be defined. At stress levels higher than the critical level, the plastic strain of subgrade soil accumulates rapidly and an unstable condition occurs, and soil tends to soften after a specific number of load applications. Using the plastic strain data obtained at stress states below the critical level, a multiple regression plastic model for cohesive subgrade soils was developed. Taking both the deviator and confining stresses into account, the model can be used to predict the permanent deformation in the subgrade of flexible pavements under repeated loading in a reasonable way.
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Liao, Chih-ying, and 廖志穎. "The Wetting Effect and Shear Modulus of Unsaturated Cohesive Subgrade Soils." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/9m6gx8.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
95
The subgrade soil often lies above the groundwater level and appears in unsaturated conditions. Since the subgrade soil is affected by the seasonal rainfall or the groundwater changes, the long-term water content of subgrade soil would increases to Equilibrium Moisture Content. This result often causes the matric suction and parameter in soils to change. In order to understand this variational process, this research used wetting simulation test by the equipment and process developed by ourselves. It could discuss the relationship between the matric suction and parameter changed. The test result showed a big influence between matric suction and parameter in soil at the beginning of the wetting process. While the water content was very close to equilibrium moisture content, this influence tended to steady. In pavement engineering, the maximum shear modulus could assess the stiffness of pavement. Therefore, this research discussed the relation between the maximum shear modulus and the other parameters for understand their relationship. This research also developed a axis-translation technique of unsaturated soil triaxial apparatus which could control different matric suction. So we could understand the influence of matric suction changed for the soil parameters directly. The test results showed: the dry of optimum sample had the highest maximum shear modulus at beginning of wetting process, but the maximum shear modulus of it decreased quickly after wetting process .So the maximum shear modulus of optimum sample became the highest. And the matric suction had high relationship with the maximum shear modulus.
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Hariharan, Narain. "Effect of Ionic Stabilization on Vertical Movement in Expansive Subgrade Soils in Texas." Thesis, 2013. http://hdl.handle.net/1969.1/151141.
Full textAbstract:
An important consideration for the successful design of flexible pavement systems in Texas is the prediction and control of the vertical change in height of the subgrade soils due to swelling upon wetting and shrinkage upon drying. The purpose of this study was two-fold. The first objective was to measure the volume change characteristics of clayey subgrade soils from the SH130 corridor in Texas through a suction based approach using the pressure plate. The second goal was to test the effects of treating the soils with the EcSS-3000 chemical stabilizer and lime on controlling the vertical movement and moisture susceptibility.
Recent research studies have indicated that the suction compression index, γh, is the parameter that has the most significant direct influence on the amount of vertical movement taking place in expansive soils. The results indicate a 40-50 % reduction in the average γh values and a similar magnitude of reduction in combined swell and shrink potential.
Further, the resilient modulus (Mr) of representative samples was compared prior to and after treatment separately with 6% hydrated lime and EcSS-3000. The purpose of measuring the Mr of the soils was to analyze the moisture susceptibility of the soils and to study the effects of subgrade stabilization on performance of typical pavement systems against the common distresses using the ME-PDG software tool. Also, the contribution of the expansive soils to pavement roughness was measured in terms of loss of serviceability (ΔPSI) using the measured Mr and vertical movement values. The analysis indicate a significant reduction in drop of Mr values of the lime and EcSS-3000 treated soils and a marked improvement in cracking and subgrade rutting characteristics of the pavements. An average reduction in ΔPSI of the pavements by 0.2 to 0.3 points was observed on the stabilized soils.
This study on expansive subgrades and the associated effects of ionic stabilization have yielded the information necessary as guidance for dealing with relevant engineering problems due to expansive soils.
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Soliman, Haithem. "Modelling of the resilient and permanent deformation behaviour of subgrade soils and unbound granular materials." 2015. http://hdl.handle.net/1993/30865.
Full textAbstract:
Laboratory characterization of subgrade soils and unbound granular materials is an essential component of the Mechanistic-Empirical Pavement Design Guide (Pavement ME). The design thickness and performance of a pavement structure are highly dependent on the deformation behaviour of subgrade and granular material. Specifications for granular materials vary among transportation agencies based on the availability of materials, climatic conditions, and function. Specifications aim to provide durable materials that meet design requirements and achieve the target design life with cost effective materials.
The objectives of the research are to:
• evaluate resilient modulus of typical fine-grained soils under traffic loading.
• evaluate resilient modulus, permanent deformation, and permeability of typical unbound granular materials.
• evaluate the effect of moisture and fines fraction on the performance of unbound granular materials and subgrade soil.
• develop prediction models for resilient modulus to improve reliability of Level 2 inputs in the Pavement ME.
• provide test data in support of updating Manitoba Infrastructure and Transportation specifications for unbound granular materials to improve the performance of pavement structures.
Resilient modulus tests were conducted on three types of subgrade soil (high plastic clay, sandy clay, and silty sand/sandy silt) at four levels of moisture content. Resilient modulus, permanent deformation and permeability tests were conducted on six gradations representing two types of granular material (100% crushed limestone and gravel) at two levels of moisture content. Prediction models were developed for resilient modulus and compared to the models developed under the Long Term Pavement Performance program. The proposed models provided more reliable predictions with lower root mean square error.
The deformation behaviour of the granular materials was classified according to the shakedown and dissipated energy approaches. Among the tested fines contents, limestone and gravel materials with optimum fines contents of 4.5% and 9%, respectively, had better resistance to plastic deformation and higher resilient modulus. The dissipated energy approach can be used to determine the stress ratio for the boundary between post compaction and stable zones from multistage triaxial testing. Result of permeability tests showed that the hydraulic conductivity of unbound granular material increased as the fines content decreased.February 2016