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Burhani, Ahmadudin. "Correlation Study on the Falling Weight Deflectometer and Light Weight Deflectometer for the Local Pavement Systems." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470663356.
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Steinert, Bryan Christopher. "Field and Laboratory Evaluation of the Portable Falling Weight Deflectometer." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/SteinertBC2005.pdf.
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Qin, Jianfeng. "Predicting Flexible Pavement Structural Response Using Falling Weight Deflectometer Deflections." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1275612839.
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Jansen, Dirk. "Temperaturkorrektur von mit dem Falling-Weight-Deflectometer gemessenen Deflexionen auf Asphaltbefestigungen." Essen Inst. für Straßenbau und Verkehrswesen, 2009. http://d-nb.info/1000217728/34.
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Mehta, Jay. "Rigid pavement condition evaluation using dynaflect and falling weight deflectometer measurements." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183652762.
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Sveinsdóttir, Berglind Ösp. "Pavement behaviour evaluation during spring thaw based on the falling weight deflectometer method." Thesis, KTH, Transportvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-45981.
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The bearing capacity of a road decreases greatly during spring thaw, when the previously frozen road begins to thaw. The extent of this decrease can be evaluated by making Falling Weight Deflectomter (FWD) measurements on the road, measuring the deflection of the road when an impact load is applied to it. The bearing capacity of the road can then be evaluated by backcalculating the layer modules with backcalculation programs, or through more simple calculations based on the deflection basin indices. Both analyses were carried out in this thesis with data from FWD measurements which were carried out on county road Lv 126 in Southern Sweden during the year 2010. The temperature and moisture content of the road were monitored during the same time. The aim with the thesis was to compare the two ways of analyses, and to find out if there is some relationship between them and the measured environmental data. The results showed that the base course layer and subbase decreased in stiffness during spring thaw about 50% while the decrease in the subgrade was 20%, compared to the backcalculated summer and autumn value. The results of the simple calculations from the deflection basin indices were well comparable to the backcalculation results. By comparing the backcalculated stiffness values to the moisture content measurements it was stated that the stiffness decreased as the moisture content increased.
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Park, Hee Mun. "Use of Falling Weight Deflectometer Multi-Load Level Data for Pavement Strength Estimation." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011120-151143.
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PARK, HEE MUN. Use of Falling Weight Deflectometer Multi-Load Level Data for Pavement Strength Estimation. (Under the direction of Y. Richard, Kim).The objective of this study is to describe a mechanistic-empirical approach to developing an analysis method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established.A condition assessment procedure for pavement layers using multi-load level FWD deflections is presented in this study. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. However, large variations were observed in the relationships between the DBCI and desg values and the subgrade CBR values for aggregate base pavements. A FWD test with a load of 53 kN or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer are found to be better indicators than the deflection basin parameter.The procedures for performance prediction of fatigue cracking and rutting are developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using both single and multi-load level deflections show good agreement with measured rut depths over a wide range of rutting potential. However, the procedure using single load level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure using multi-load level deflections can estimate an excessive level of rutting quite well and, thus, improve the quality of prediction for rutting potential in flexible pavements.
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Meier, Roger William. "Backcalculation of flexible pavement moduli from falling weight deflectometer data using artificial neural networks." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/18991.
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Schweiger, Daniel J. "Instrumentation of flexible pavement." Ohio University / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1178911279.
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Bueno, Lucas Dotto. "AVALIAÇÃO DEFLECTOMÉTRICA E DE RIGIDEZ: ESTUDO DE CASO EM TRÊS TRECHOS MONITORADOS EM SANTA MARIA/RS." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/7926.
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Petróleo Brasileiro S/AIt is unusual practice, in national projects of new pavements and restorations, the consideration of viscoelastic behavior and non-linear elastic of materials that compound or will compound the layers of pavement. However, the linear elastic response is a simplification of the actual behavior of the pavements layers, since the materials used in the structure have dependent stiffness of the stress state (granular layers and subgrades) or temperature and load application time (asphalt concrete). Therefore, it was aimed to study the behavior of the pavements structures of three monitored sections in the city of Santa Maria/RS. For this, tests were performed with the equipment FWD applying four different loads in each stake that compounds the extension of the three sections. It was found from deflection basins and backcalculated resilient moduli the nonlinear elastic behavior of granular layers (base and sub-base) of the sections 1 and 2, with resilient modulus directly proportional to the increase of the confining pressure. The subgrades of both sections exhibited varied behavior and can be simplified by the linear elasticity without considerable loss. The same happened to the asphalt concrete of section 1. On the other hand, the coating of the section 2 resulted in resilient modules dependent of the increase of vertical surface tension in the center of the load plate. In relation to section 3, the results related only to deflection measures indicated mostly behavior near of linearity in all evaluated reading distances, except for that carried out under the load application. Sequentially to load pulses, also were determined deflections with the Benkelman beam, aiming to find a local correlation between the results obtained from different equipments. The deflections basins indicated higher values, measured with the beam, in relation to those determined by FWD. Consequently, the resilient modules were higher when determined from the backcalculation of the readings taken with FWD, in relation to Benkelman beam. In parallel, it was verified and quantified the influence of bounding conditions between the layers and correction, total or partial, of deflections basins, depending on the temperature, in backcalculated resilient moduli. It was found that the assignment of total bounding in the interfaces between the layers reduces considerably the backcalculated resilient moduli of granular materials. Regarding to the temperature correction, it is appropriate the determination of the rigidity of the granular materials and the subgrade by performing backcalculation without any adjustment in the field basins. Taking these values as a basis, it was considered appropriate to repeat the iterative procedure, with adjustment of the deflections depending on the temperature in the initial readings, thereby determining the new asphalt concrete resilient moduli.
Não é prática usual, em projetos nacionais de pavimentos novos e restaurações, a consideração do comportamento viscoelástico e elástico não linear dos materiais que constituem, ou que irão constituir as camadas do pavimento. Todavia, a resposta elástica linear é uma simplificação do comportamento real das camadas dos pavimentos, já que os materiais empregados na estrutura possuem rigidez dependente do estado de tensões (camadas granulares e subleitos) ou da temperatura e tempo de aplicação de carga (concretos asfálticos). Em vista disso, buscou-se estudar o comportamento das estruturas dos pavimentos de três trechos monitorados, na cidade de Santa Maria/RS. Para isso, foram realizados ensaios com o equipamento FWD, aplicando quatro diferentes carregamentos em cada estaca que compõe a extensão dos três trechos. Verificou-se, a partir das bacias deflectométricas e dos módulos de resiliência retroanalisados, o comportamento elástico não linear das camadas granulares (base e sub-base) dos Trechos 1 e 2, com módulo de resiliência diretamente proporcional ao incremento da tensão confinante. Os subleitos de dois trechos exibiram comportamento variado, podendo ser simplificados pela elasticidade linear, sem prejuízo considerável. O mesmo aconteceu para o concreto asfáltico do Trecho 1. Já o revestimento do Trecho 2 resultou em módulos resilientes dependentes do incremento da tensão vertical na superfície no centro da placa de carga. Em relação ao Trecho 3, os resultados, referentes apenas às medidas deflectométricas, indicaram comportamento majoritariamente próximo da linearidade em todas as distâncias de leitura avaliadas, com exceção daquela medida abaixo do centro da placa de carga. Sequencialmente aos pulsos de carga, foram determinadas também as deflexões com a viga Benkelman, objetivando encontrar uma correlação local entre os resultados obtidos a partir dos diferentes equipamentos. As bacias deflectométricas indicaram valores superiores, medidos com a viga, em relação àqueles determinados pelo FWD. Consequentemente, os módulos de resiliência foram maiores quando determinados a partir da retroanálise de leituras efetuadas com o FWD, em relação à viga Benkelman. Em paralelo, foi verificada e quantificada a influência das condições de aderência entre as camadas e da correção, total ou parcial, das bacias deflectométricas, em função da temperatura, nos módulos de resiliência retroanalisados. Constatou-se que a atribuição de aderência total nas interfaces entre as camadas reduz consideravelmente os módulos de resiliência retroanalisados dos materiais granulares. Em relação à correção de temperatura, verificou-se adequada a determinação da rigidez dos materiais granulares e subleito mediante a realização da retroanálise sem nenhum ajuste nas bacias de campo. Tomando estes valores como base, julgou-se pertinente a repetição do procedimento iterativo, com ajuste das deflexões em função da temperatura nas leituras iniciais, determinando assim o novo módulo de resiliência do revestimento.
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Roussel, Jean-Marie. "Apport de la viscoélasticité dans l’analyse dynamique des essais au Heavy Weight Deflectometer." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSET015.
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Le Heavy ou Falling Weight Deflectometer (F/HWD), est un appareil d’auscultation non destructive des chaussées basé sur la mesure de la déflexion engendrée par un chargement impulsionnel. Les essais F/HWD sont généralement exploités par des méthodes d’analyse inverse, dont le but est de déterminer les propriétés mécaniques des couches de chaussée. Ces méthodes consistent en la recherche du jeu de propriétés mécaniques pour lequel les déflexions calculées à l’aide de modèles numériques sont comparables aux déflexions mesurées in situ. Malgré son utilisation très répandue sur chaussées routières et aéroportuaires, il s’avère que les données de cet essai sont souvent interprétées dans un cadre d’hypothèses discutable car la méthode élastostatique couramment utilisée ne prend pas en compte les effets dynamiques et limite le comportement des matériaux bitumineux à l’élasticité linéaire. Ce travail, dans le cadre d’une coopération entre le Service Technique de l’Aviation Civile (STAC) et le Laboratoire de Tribologie et de Dynamique des Systèmes (LTDS) a pour objectif principal d’étudier les méthodes d’analyse de l’essai F/HWD en incluant les effets dynamiques et les propriétés viscoélastiques linéaires des matériaux bitumineux. Au cours des travaux entrepris, le fonctionnement de l’appareil F/HWD a été analysé grâce à des systèmes d’instrumentation externes. Puis deux méthodes de simulation de l’essai F/HWD ont été développées : la Méthode des Eléments Finis dans le domaine temporel et la Méthode des Eléments Spectraux dans le domaine fréquentiel. Ces deux outils permettent le calcul de la réponse d’une chaussée sous un chargement impulsionnel de type F/HWD selon plusieurs hypothèses d’équilibre (quasi-statique et dynamique) et de comportement des matériaux bitumineux (élastique linéaire et viscoélastique linéaire). Enfin, une méthode d’analyse inverse viscoélastique dynamique est proposée. Après avoir été vérifiée et évaluée, elle est appliquée à des essais HWD réalisés sur la planche expérimentale du STAC à différentes températures entre 0°C et 30°C. Les propriétés viscoélastiques linéaires déduites des essais HWD sont également comparées aux résultats d’essais de module complexe sur les matériaux de la même planche réalisés au laboratoire de l’ENTPEThe Heavy or Falling Weight Deflectometer (F/HWD) is a non-destructive pavement assessment device. The F/HWD test is based on the measurement of the deflection generated by an impulse loading. F/HWD tests are generally analysed by inverse analysis methods, the purpose of which is to determine the mechanical properties of the pavement layers. These methods are based on the search of mechanical properties for which the deflections calculated using numerical models are comparable to the deflections measured in situ. Despite its widespread use on road and airport pavements, it turns out that the data from this test are often interpreted within a questionable background because the elastostatic method commonly used does not consider dynamic effects and limits the behaviour of bituminous materials to linear elasticity. This work, in the framework of a cooperation between the Civil Aviation Technical Centre (STAC) and the Laboratory of Tribology and Systems Dynamics (LTDS) has the main objective to study the analysis methods of the F/HWD test data by including the dynamic effects and the linear viscoelastic properties of bituminous materials. During this work, the F/HWD devices has been studied with external sensors. Then, two numerical methods for simulating the F/HWD test were set up: the Finite Element Method in time domain and the Spectral Element Method in frequency domain. These two tools allow the calculation of the pavement response under F/HWD impulse loading according to several hypotheses of equilibrium (quasi-static and dynamic) and behaviour of bituminous materials (linear elastic and linear viscoelastic). Finally, a dynamic viscoelastic inverse analysis method is proposed. After having been verified and evaluated, it is applied to HWD tests carried out on the STAC test facility at several pavement temperatures between 0°C and 30°C. The results are compared with those obtained by the classical elastostatic and elastodynamic methods. The linear viscoelastic properties deduced from the HWD tests are also compared to the results of complex modulus tests on the materials of the test facility carried out in the ENTPE laboratory
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Alkasawneh, Wael Mohammad. "Backcalculation of Pavement Moduli Using Genetic Algorithms." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1176831189.
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Wasniak, Daniel L. "Subgrade and base variability on the Ohio SHRP test road." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175276775.
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Luis, Andre Denis. "Utilização do equipamento tipo Falling Weight Deflectometer para medição de deflexão recuperavel para diferentes tipos de pavimentos asfalticos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258119.
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Orientador: João Virgilio MerighiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Esta pesquisa versa sobre a utilização do equipamento FWD - Falling Weight Deflectometer, sendo analisados os diversos aspectos que influenciam nos resultados dos ensaios com o equipamento FWD. Dificuldade de interpretações das especificidades de tipos distintos de estruturas de pavimentos e uma vasta gama de correlações com a Viga Benkelman, as quais foram deduzidas por autores de diversas nacionalidades, demonstram que não há regra harmônica para os estudos. Assim, faz se imprescindível a percepção acurada, a consciência e experiência adquirida do engenheiro de projeto em cada situação. Esta hipótese foi corroborada pelo estudo dos ensaios realizados em malha viária experimental, abordados nesta dissertação. São propostos ainda temas relevantes para futuro desenvolvimento que possam agregar em confiabilidade e em economia dos projetos de pavimentação na Engenharia Nacional. Este trabalho foi desenvolvido utilizando-se a bibliografia sobre deflectometria internacional e brasileira, abrangendo os editais de concessões rodoviárias estaduais e federais.
Abstract: This research is about the use of equipment FWO - Falling Weight Deflectometer, and analyzed the various aspects that influence the results of tests with the FWO equipment. Difficulty in interpretation of the peculiarities of different types of pavement structures and a wide range of correlations with the Benkelman beam, which were derived by authors from different nationalities, shows that there is no rule for harmonic studies. Thus, it is essential to accurate perception, awareness and experience of the design engineer in every situation. This hypothesis was confirmed by the study of tests on experimental road network, discussed in this dissertation. Are still relevant topics proposed for future development that can add reliability and economy of paving projects in the National Engineering. This work was developed using the literature on international and Brazilian deflection, covering the tenders for state andfederal road concessions.
Mestrado
Transportes
Mestre em Engenharia Civil
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Young, Tyler B. "Early Age Assessment of Cement Treated Materials." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/885.
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In order to avoid the occurrence of early-age damage, cement-treated base (CTB) materials must be allowed to cure for a period of time before the pavement can be opened to traffic. The purpose of this research was to evaluate the utility of the soil stiffness gauge (SSG), heavy Clegg impact soil tester (CIST), portable falling-weight deflectometer (PFWD), dynamic cone penetrometer, and falling-weight deflectometer for assessing early-age strength gain of cement-stabilized materials. Experimentation was performed at four sites on a pavement reconstruction project along Interstate 84 near Morgan, Utah, and three sites along Highway 91 near Richmond, Utah; cement stabilization was used to construct CTB layers at both locations. Each site was stationed to facilitate repeated measurements at the same locations with different devices and at different curing times. Because of the considerable attention they have received in the pavement construction industry for routine quality control and quality assurance programs, the SSG, CIST, and PFWD were the primary focus of the research. Statistical techniques were utilized to evaluate the sensitivity to curing time, repeatability, and efficiency of these devices. In addition, the ruggedness and ease of use of each device were evaluated. The test results indicate that the CIST data were more sensitive to curing time than the SSG and PFWD data at the majority of the cement-treated sites during the first 72 hours after construction. Furthermore, the results indicate that the CIST is superior to the other instruments with respect to repeatability, efficiency, ruggedness, and ease of use. Because the CIST is less expensive than the SSG and PFWD, it is more likely to be purchased by pavement engineers and contractors involved with construction of CTBs. For these reasons, this research suggests that the CIST offers greater overall utility than the SSG or PFWD for monitoring early-age strength gain of CTB. Further research is needed to identify appropriate threshold CIST values at which CTB layers develop sufficient strength to resist permanent deformation or marring under different types of trafficking.
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Appea, Alexander Kwasi. "In-Situ Behavior of Geosynthetically Stabilized Flexible Pavement." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/9570.
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The purpose of a geotextile separator beneath a granular base, or subbase in a flexible pavement system is to prevent the road aggregate and the underlying subgrade from intermixing. It has been hypothesized that in the absence of a geotextile, intermixing between base course aggregate and soft subgrade occurs. Nine heavily instrumented flexible pavement test sections were built in Bedford County Virginia to investigate the benefits of geosynthetic stabilization in flexible pavements. Three groups of different base course thicknesses (100, 150 and 200mm) test sections were constructed with either geotextile or geogrid stabilization or no stabilization. Woven geotextile was used in sections 2, 5 and 8. Geogrids were used in sections 3, 6 and 9, and sections 1, 4 and 7 were controls. Six Falling weight deflectometer (FWD) tests were performed on all the nine sections over 30 months. The nine sections were subjected to at least 5 load drops with wide loading range each time. The measured deflections were analyzed using the MODULUS back-calculation program to determine layer moduli. The measured deflections were used together with elastic, viscoelastic and the MODULUS program to determine the extent of intermixing at base-subgrade interface. The study concluded that a transition layer would develop when a separator is absent, especially in the weak sections (designed to fail in three years). Other measurements such as in-situ stresses, rut depth, and subsurface profiling (using ground penetrating radar) support the conclusion of the development of a transition layer.Master of Science
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Sharkins, Anthony August. "Instrumentation for SPS-2." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178043493.
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Jansen, Dirk [Verfasser]. "Temperaturkorrektur von mit dem Falling-Weight-Deflectometer gemessenen Deflexionen auf Asphaltbefestigungen / Dirk Jansen. Universität Duisburg, Essen, Institut für Straßenbau und Verkehrswesen." Essen : Inst. für Straßenbau und Verkehrswesen, 2009. http://d-nb.info/1000217728/34.
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Macioce, Damon J. "Performance of instrumented flexible pavement." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177092747.
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Knauff, Marcel [Verfasser], Edeltraud [Akademischer Betreuer] Straube, Doru C. [Akademischer Betreuer] Lupascu, and Jürgen [Akademischer Betreuer] Hothan. "Quantitative Bewertung der Tragfähigkeit von Asphaltbefestigungen durch Falling-Weight-Deflectometer Messungen / Marcel Knauff. Gutachter: Doru C. Lupascu ; Jürgen Hothan. Betreuer: Edeltraud Straube." Duisburg, 2015. http://d-nb.info/1074825195/34.
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Walters, Shane A. "Field performance of dowel bars." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175281160.
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NASCIMENTO, Mauro Henrique Alves. "Análise da incompatibilidade de rigidez entre camadas de revestimentos asfálticos na ocorrência de slippage em pavimento aeroportuário." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/386.
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Com a finalidade de sanar as degradações do pavimento, devem-se realizar estudos avaliativos das condições estruturais, objetivando identificar as possíveis causas dos defeitos e sobretudo fornecer subsídios, sobre quais medidas corretivas devem ser adotadas para a restauração das condições adequadas e aceitáveis do pavimento. Diante destas circunstâncias, o presente trabalho tem como objetivo identificar as possíveis causas das ocorrências dos defeitos parabólicos observados na superfície dos pavimentos flexíveis das pistas de pouso e decolagem e de taxiamento do Aeroporto Internacional de Natal. Para isso, realizou-se uma avaliação estrutural não destrutiva, por meio do levantamento deflectométrico com o Falling Weight Deflectometer (FWD), o qual foi realizado em toda a extensão das pistas e em diversas faixas de aquisição de dados. Com o FWD obteve-se as bacias de deflexões que possibilitaram por processo de retroanálise, por meio do software BAKFAA 2.0, caracterizar o comportamento resiliente in situ das camadas do pavimento. Com o software ELSYM5 realizou-se a análise empírico-mecanística, para verificar os níveis de tensões cisalhantes atuantes nas diversas profundidades das camadas do pavimento, inclusive na interface de ligação entre as camadas asfálticas. Também foram realizados ensaios laboratoriais de caracterização das propriedades mecânicas, tais como: módulo de resiliência, resistência a tração indireta e o ensaio de Leutner shear Test. Concluiu-se que os defeitos observados na superfície das pistas enquadravam-se na série de defeitos classificados de escorregamento do revestimento asfáltico, ou Slippage, e que os fatores que culminaram na ocorrência destes defeitos relacionam-se com a baixa aderência da interface de ligação e com a incompatibilidade de rigidez entre as camadas adjacentes de mistura asfálticas.
In order to remedy pavement degradation, evaluation studies of the structural conditions should be carried out to identify the possible causes of the defects and, above all, provide information on which corrective measures should be taken to restore adequat and acceptable conditions of the pavement. In view of these circumstances, the present work has the objective of identifying the possible causes of parabolic defects seen in the surface of the flexible pavements of the landing and take - off runways and taxiways of Natal International Airport runway. For this, a non-destructive structural evaluation was carried out by means of the deflectometric survey with the Falling Weight Deflectometer (FWD), which was carried out along the whole length of the tracks and in several ranges of data acquisition. With the FWD, the deflection basins were obtained, which enabled the BAKFAA 2.0 software to characterize the in situ resilient behavior of the pavement layers by means of a retro-analysis process. With the ELSYM5 software, the empirical-mechanistic analysis was performed to verify the levels of shear stresses at different depths of the pavement layers, including the interface between the asphalt layers. Furthermore, laboratory characterization of mechanical properties such as: resilience modulus, tensile strength and Leutner shear test were carried out. It is concluded that the defects observed on the runway surface fit into the series of defects classified as slippage of the asphalt coating, or Slippage, and that the factors that culminated in the occurrence of these defects are related to the low adhesion of the interface and With the incompatibility of stiffness between the adjacent layers of asphalt mixtures.
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Liao, Yun. "Viscoelastic FE Modeling of Asphalt Pavements and Its Application to U.S. 30 Perpetual Pavement." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1190919049.
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Zhu, Junqing. "Forensic Study and Finite Element Modeling of Unbonded Concrete Overlay Pavements on Interstate 70 & 77 in Ohio." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1501156328255479.
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Coleri, Erdem. "Relationship Between Resilient Modulus And Soil Index Properties Of Unbound Materials." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608660/index.pdf.
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In the mechanistic design approach, which has already been started to utilize in several countries, the variations in material properties are better taken into account based on fundemental engineering principles. Resilient modulus is the most important material property that is used in the mechanistic design since it describes the true martial performance of unbound pavement layers under traffic loading. In this thesis, the objective is to determine the resilient modulus, used in the mechanistic design of pavement structures, for the unbound material types used in Turkey and develop linear and nonlinear prediction models to determine resilient response of unbound layers based on soil index properties, California Bearing Ratio (CBR) and Light Falling Weight Deflectometer (LFWD) test results. Application of
genetic algorithm and curve shifting methodology to estimate design resilient modulus at various stress states is also investigated using the test results for finegrained soils. Resilient modulus estimation for a constant stress state based on genetic algorithm and curve shifting methodolgy is quite promising for fine-grained soils since nonlinear constitutive models do not have the capability of representing resilient responses under different conditions. Furthermore, tree-based modeling is discussed as an alternative way to develop resilient modulus prediction models. The outcome of the study will be a basis for the performance based design specifications
of flexible pavements.
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Pinto, Filho Washington Luiz. "Avaliação e diagnóstico de vias urbanas expressas de Manaus: condições estruturais e funcionais." Universidade Federal do Amazonas, 2013. http://tede.ufam.edu.br/handle/tede/4621.
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The city of Manaus has the highest average growth rates of the fleet, according to the DENATRAN. Over the past 10 years, the fleet of cars rose from 124,840 (2003) to 297,473 cars (2013) and 3,179 buses (2003) to 7,398 buses (2013). This equates to a 138% increase. Moreover, although, according to DENATRAN in 2003, Manaus was 220,816 vehicles. In 2013, Manaus already has 551,455 registered vehicles in its municipal fleet, which equates to an increase of almost 150%. As a result of this growth, the city roads are presented with its ability to flow and dead, visually, with their decks completely deformed. In this sense, we tried to carry this research, a structural evaluation of pavements of the main streets of the town (Av. Constantino Nery, Avenida Djalma Batista, Recife Av, Av and Av Efigênio Sales Paraíba), employing the technique FWD (Falling Weight Deflectometer) in the diagnosis of the pavement structures of these pathways. The results showed that the structures of those decks still have the condition to withstand the demands of traffic load applied to them, since their structural quality obtained by the mentioned technique, presented in good condition, according to the floors they presented deflections smaller than the allowed maximum, and radii of curvature much greater than 100 m. In addition, analysis was performed of the safety of the coating with respect to tire-pavement grip, which presented values for microtexture and macrotexture well outside the ranges recommended by the standards.
A cidade de Manaus apresenta uma das maiores taxas de crescimento médio da frota de veículos, segundo dados do DENATRAN. Nos últimos 10 anos, a frota de automóveis aumentou de 124.840 (2003) para 297.473 automóveis (2013) e 3.179 ônibus (2003) para 7.398 ônibus (2013). Isto equivale a um aumento de 138 %. Ademais, ainda, segundo o DENATRAN, em 2003, Manaus tinha 220.816 veículos. Em 2013, Manaus já possui 551.455 veículos registrados na sua frota municipal, o que equivale a um aumento de quase 150 %. Como consequência deste crescimento, as vias da cidade apresentam-se com sua capacidade de fluxo inoperante e, visualmente, com seus pavimentos totalmente deformados. Neste sentido, procurou-se realizar, nesta pesquisa, uma avaliação estrutural dos pavimentos das principais vias da cidade (Av. Constantino Nery, Av. Djalma Batista, Av. Recife, Av. Paraíba e Av. Efigênio Sales), empregando a técnica FWD (Falling Weight Deflectometer) no diagnóstico das estruturas dos pavimentos das referidas vias. Os resultados obtidos mostraram que as estruturas daqueles pavimentos ainda apresentam a condição de suportar as solicitações de carga de tráfego a elas aplicadas, visto que sua qualidade estrutural, obtida pela técnica mencionada, apresentou-se em boas condições, em função dos pavimentos terem apresentado deflexões máximas inferiores às admissíveis, bem como raios de curvatura muito superiores a 100 m. Como complemento à análise estrutural, realizou-se análise das condições funcionais do revestimento com relação à aderência pneu-pavimento, a qual apresentou valores para microtextura e macrotextura bem fora dos intervalos recomendados pelas normas.
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Rahimi, Nahoujy Mahdi [Verfasser], Martin [Gutachter] Radenberg, and J. Stefan [Gutachter] Bald. "An artifical neural network approach to model and predict asphalt deflections as a complement to experimental measurements by falling weight deflectometer / Mahdi Rahimi Nahoujy ; Gutachter: Martin Radenberg, J. Stefan Bald ; Fakultät für Bau- und Umweltingenieurwissenschaften." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1212664256/34.
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Capace, Brunella. "NDT application in Transport Asset Management. QA/QC performance specifications in pavement construction and maintenance." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4100.
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Nowadays, in Transport Asset Management, there is the need to identify measures to guarantee high levels of performance over time. The application of Non-Destructive Techniques, through high-efficiency equipment, turns out to be an optimal solution to ensure the quality of transport infrastructures.
Asset Management take into account the importance of monitoring the performance characteristics of the transport infrastructures and QA/QC performance-based contracts specifications in order to guarantee the preservation of environmental, social and economic resources, as well.
This study consists of two parts of research activity: in field tests and numerical simulations.
The first part consists of in situ experimental activities to investigate both road and rail transport infrastructures. The tests have shown the versatility of high-performance instruments, such as FWD, LWD, GPR and ARAN, in railway monitoring, in the evaluation of ballast conditions and sleeper/ballast interaction, and also in the reuse of volcanic ashes that after stabilization can be used in road subbase layers. The high-efficiency equipment allow a faster execution of the tests with the possibility of a higher number of measurements, the combination of several instruments at the same time with a continuous mapping of the infrastructures, performance measures and a significant cost reduction.
In the second part, the study focuses more specifically on road pavements. Considering several flexible pavements pulled out from the Italian Catalog, numerical simulations of FWD tests were carried out in the hypothesis of multilayer elastic theory with the aim to develop performance-based criteria and specifications for QC of pavement construction work.
The results allow to estimate effects of structural deficits in the perspective of future performance and Life Cycle Cost Analysis in order to quantify penalties to restore expected higher maintenance costs.
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Ossich, Giulio. "Utilizzo di support vector machine per l'identificazione delle caratteristiche meccaniche delle sovrastrutture stradali a partire da misure deflettometriche." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2750.
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2006/2007L’obiettivo di questo lavoro è stato lo sviluppo di una metodologia per l’identificazione delle caratteristiche meccaniche dei materiali costituenti le pavimentazioni stradali basate sull’utilizzo della tecnica SVM (Support Vector Machine) di recente sviluppo. Tale procedura che fa parte delle cosiddette tecniche di apprendimento è stata adottata per la complessità numerica del problema indagato che consiste nell’analisi dinamica di pavimentazioni stradali sottoposte ad un carico impulsivo. Vista la natura dinamica del problema infatti le tradizionali tecniche di backcalculation che prevedono un procedimento iterativo che interviene sui parametri del problema fino ad ottenere, attraverso delle simulazioni, i medesimi risultati misurati, rendono il procedimento molto dispendioso in termini di tempo. La procedura messa a punto in questa tesi invece elimina tale problema utilizzando degli algoritmi di apprendimento che prevedono una prima fase di addestramento nella quale sono state eseguite migliaia di simulazioni in campo dinamico variando i vari parametri del problema. Successivamente, quando la “macchina” risulta addestrata il problema viene risolto in maniera diretta eliminando tutti i procedimenti iterativi che altrimenti dovrebbero essere eseguiti per ogni test e che con questa tecnica vengono “effettuati” una sola volta durante la fase di apprendimento. Tale procedimento è stato in grado di dare buoni risultati in campo dinamico ottenendo errori percentuali modesti in tutto il range di valori considerati potendo quindi considerare tale approccio una valida alternativa ai metodi iterativi. Gli argomenti sono stati trattati in modo rigoroso dando spazio ad approfondimenti teorici sia dal punto di vista delle meccanica della pavimentazione che dal punto di vista delle tecniche di identificazione mettendo inoltre in luce alcuni aspetti migliorativi alle tecniche utilizzate.
XX Ciclo
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Mataramba, Kankanamge Kasun Dilhara Wimalasena. "Evalutate the performance of geosynthetic reinforced subgrades under monotonic loading." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235924/1/Kasun_Kankanamge_Thesis.pdf.
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A series of large-scale pavement model tests were conducted in a laboratory environment to investigate the effect of geosynthetics in improving the modulus of weak subgrades. Then, a series of supplement design charts that could be useful for industry practitioners to design geosynthetic reinforced flexible pavements were developed. The outcomes of this study promote the use of geosynthetics in road construction to make economical, environmentally friendly, climate resilient, and sustainable road infrastructure.
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Paliukaitė, Miglė. "Klimato įtakos automobilių kelių asfalto dangos konstrukcijos stipriui tyrimai ir vertinimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100701_091723-23606.
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Analizuojama asfalto dangos konstrukcijos elgsena Lietuvos klimato sąlygomis, įvertinant temperatūros ir drėgnio, kaip vienų iš svarbiausių klimato veiksnių, įtaką kelio asfalto dangos konstrukcijos stipriui. Pateikta krintančio svorio deflektometro matavimo metodikų apžvalga kitose šalyse. Atlikta temperatūros ir drėgnio kiekvienos dienos pokyčių analizė, įvertinant jų įtaką dangos konstrukcijai. Nustatyta kelio dangos stiprio ir Eo modulio priklausomybė nuo dangos temperatūros, matuojant kelio dangos įlinkius krintančio svorio deflektometru. Kai asfalto dangos stipris matuojamas skirtingu metų laiku ar įvairiu paros metu, tai Eo modulio reikšmės turi būti redukuojamos priimtai standartinei temperatūrai. Eksperimentiniame asfalto dangų konstrukcijų ruože atliktu tyrimu patikslintas temperatūrinis redukcijos koeficientas, kuris leidžia krintančio svorio deflektometru nustatytas asfalto dangos sluoksnių Eo modulio vertes redukuoti standartinei +20 °C temperatūrai.This final master thesis performs asphalt pavement structural behavior of the Lithuanian climate conditions, taking into account the temperature and moisture, as one of the most important climatic factors that influence the road asphalt pavement structural strength. The Falling Weight Deflectometer (FWD) measurement methods used in other countries are presented. The temperature and moisture changes in the day are analysed, evaluating their impact on pavement design. The strength of asphalt pavement layers, as well as Eo modulus values, measured using the falling weight deflectometer, strongly depend on the pavement temperature. When we use deflectometer for measuring asphalt pavement strength at different environmental conditions and in different season, the values of Eo modulus should be reduced to the assumed standard temperature. So during this research at the experimental asphalt pavement structure the temperature correction factor was revised. The use of this factor enables to adjust the Eo modulus values of asphalt pavement layers measured by the Falling Weight Deflectometer to the standard temperature of +20 °C.
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Hope, Charles A. "Evaluation of Portable Devices for Monitoring Microcracking of Cement-Treated Base Layers." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2965.
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A relatively new method used to reduce the amount of cement-treated base (CTB) shrinkage cracking is microcracking of the CTB shortly after construction. Three portable instruments used in this study for monitoring the microcracking process include the heavy Clegg impact soil tester (CIST), portable falling-weight deflectometer (PFWD), and soil stiffness gauge (SSG). The specific objectives of this research were 1) to evaluate the sensitivity of each of the three portable instruments to microcracking, and 2) to compare measurements of CTB stiffness reduction obtained using the three devices. The test locations included in this study were Redwood Drive and Dale Avenue in Salt Lake City, Utah; 300 South in Spanish Fork, Utah; and a private access road in Wyoming. Experimental testing in the field consisted of randomized stationing at each site; sampling the CTB immediately after the cement was mixed into the reclaimed base material; compacting specimens for laboratory testing; and testing the CTB immediately after construction, immediately before microcracking, immediately after each pass of the vibratory roller during the microcracking process, and, in some instances, three days after microcracking. Several linear regression analyses were performed after data were collected using the CIST, PFWD, and SSG during the microcracking process to meet the objectives of this research. Results from the statistical analyses designed to evaluate the sensitivity of each of the three portable instruments to microcracking indicate that the PFWD and SSG are sensitive to microcracking, while the CIST is insensitive to microcracking. Results from the statistical analyses designed to compare measurements of CTB stiffness reduction demonstrate that neither of the instrument correlations involving the CIST are statistically significant. Only the correlation between the PFWD and SSG was shown to be statistically significant. Given the results of this research, engineers and contractors should utilize the PFWD or SSG for monitoring microcracking of CTB layers. The heavy CIST is unsuitable for monitoring microcracking and should not be used. For deriving target CTB stiffness reductions measured using either the PFWD or SSG from specified targets measured using the other, engineers and contractors should utilize the correlation chart developed in this research.
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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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Bartku, Elaine Cleare. "In-Situ Recycling: Applications, Guidelines, and Case Study for Local Governments." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49669.
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This thesis investigates the application of In-Situ Recycling and provides guidelines for localities to aid in the selection of recycling methods, as well as documents a local government's experience with Cold In-Place Recycling. The recycling methods discussed in this study include Cold In-Place Recycling (CIR), Hot In-Place Recycling (HIR), and Full Depth Reclamation (FDR). These methods are performed onsite and in-place in a continuous process of milling, mixing, and placement.
The In-Situ Recycling guidelines include suggestions based on: traffic characteristics, existing road condition, distress types, road access, local climate, road geometry, and other road characteristics. The guidelines are based on information from sources including NCHRP Synthesis 421, American Recycling and Reclamation Association (ARRA), FHWA, and state agencies with recycling experience.
This study also resulted in documenting obstacles that localities may face when in-situ recycling, as well as the impact of limited experience with recycling. The study also evaluated the construction of Cold In-Place Recycled pavement sections in Christiansburg, VA, using Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR). Additionally, using the FWD and GPR data, alternate recycled designs were proposed in addition to a cost comparison to a conventional design.Master of Science
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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.
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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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Quick, Tyler James. "Temporal and Spatial Variability in Base Materials Treated with Asphalt Emulsion." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2715.
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The first objective of this research was to investigate temporal trends in the mechanical properties of base materials stabilized with asphalt emulsion and to assess the rate at which emulsion-treated base (ETB) design properties are achieved. The second objective of this research was to identify construction and environmental factors most correlated to specific mechanical properties of ETB layers and to determine which construction factors exhibit the greatest variability. Additional statistical analysis was performed to determine if significant differences existed between different test sections on a given project. In this research, three experimental sections were established along a pavement reconstruction project near Saratoga Springs, Utah. Field tests were performed to assess the structural properties of the ETB immediately following construction and at 2, 3, 7, and 14 days; 4 months; and 1 year. Measured values were plotted against time to determine trends in ETB strength development. Several statistical analyses were then performed on the collected data. Modulus values were consistently low in all three sections during the first two weeks of testing, increased dramatically by 4 months, and then decreased considerably by 1 year. During the first two weeks following construction, the average ETB structural coefficient was 0.04. Only two of the three sections reached the design structural coefficient of 0.25, which occurred after approximately 3 months; however, the average structural coefficient measured for all three sections after 1 year of curing, which included a winter, was only 47 percent of the design strength. The results of this research show that, while pavement capacity is sufficient at 4 months, it is severely reduced during the first two weeks and at 1 year. Trafficking under these reduced capacities is not recommended. Statistical analysis showed that gradation, binder change during emulsion treatment, and moisture content have the most significant impact on ETB structural properties. Gradation and binder change during emulsion treatment also exhibited significant variability; tighter specifications on material gradations and improved uniformity in emulsion distribution should therefore be considered. Because of the negative impacts of moisture on ETB strength development, construction should not be performed in conditions of excess moisture.
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Pokluda, Radim. "Stavební recykláty pro stmelené směsi vozovek." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226040.
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In the theoretical part of the thesis are generally characterized hydraulically bound mixtures, their types, classification systems, manufacturing technology and the laying. There are also described experiences from abroad with the use secondary and recycled materials in hydraulically bound mixtures. The practical part deals with the experimental verification of the possibility of the use of secondary materials in hydraulically bound mixtures in construction of road infrastructure. In road laboratory Institute of road structures Brno university of technology was the five proposed mixtures, an assessment of their parameters with regard to the possibility of using these mixtures in the road sub-base layers. The work is also aimed at comparison of results elasticity modules reached laboratory testing and experimental measurements on road polygon.
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Shu-PingLan and 藍舒平. "Evaluation of Highway Pavements Using Falling Weight Deflectometer." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/yq2ypt.
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碩士國立成功大學
土木工程學系
104
The falling weight deflectometer (FWD) has been used extensively of nondestructive testing (NDT) to support pavement design, rehabilitation strategy selection, overall bearing capacity, and other pavement management activities. These data are used to determine the load-response properties of the pavement structure and subgrade. This study consists of 2 parts: (1) Investigating the 1st National Freeway Miaoli section three years FWD data collected by Central Area National Freeway Bureau. However, the tests were conducted during different seasons. To get comparable results, the measured deflections have to be corrected to a reference temperature. Compare and analysis the data with the following 5 methods: normalized D0 deflection, impulse stiffness modulus (ISM), AASHTO Mr equation, Area method, and Deflection Bowl Parameter method. (2) Investigating the Gang Shan district in situ testing FWD data. Different from part 1, temperatures are measured complete and accurate on surface temperature and in-depth temperature of pavement structures. More data on other thicknesses are being collected. Material types and layer thicknesses can be measured by using field cores. Evaluating the pavement structural capacity with the above 5 methods.
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Hou-IeongKuan and 關灝揚. "Structural Capacity Evaluation of Pavements Subjected to Falling Weight Deflectometer." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/h42w25.
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碩士國立成功大學
土木工程學系
104
Although Falling Weight Deflectometer (FWD) is widely used in pavement performance test, FWD data has not been fully analyzed, resulting in limited use of FWD as a follow-up assessment. This study investigates the three years FWD data collected by Central Area National Freeway Bureau, and the Gang Shan district in situ testing FWD data, respectively using normalized deflection, impulse stiffness modulus (ISM), AASHTO Mr equation, Area method and Area parameter (Ar’) such methods to analyze, and with backcalculated modulus, evaluating the pavement structural capacity. Normalized D0 deflection and impulse stiffness modulus ISM can indicate the status of the pavement, however, they are susceptible to the temperature and thickness of pavement surface layer; AASHTO Mr equation can determine the variety of the subgrade among the testing sections, but comparison with the backcalculated results shows that AASHTO Mr equation will have a higher subgrade resilient modulus. As Area method involves more deflections to calculate, it is a better pavement strength index, however, it may have a misjudging result when the overall deflection bowl drops or rises, weak pavement and strong pavement may have similar Area value. Area parameter Ar’ is the most feasible method among all the indicators, it involves more deflections and can assess pavement situation; backcalculation result shows that Area method and Area parameter Ar’ are more susceptible to be affected by pavement surface rather than crushed stone subbase and subgrade.
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Lin, Heng-Cheng, and 林恒丞. "Application of Portable Falling Weight Deflectometer for Flexible Pavement Condition Assessment." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/23156209499559143854.
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碩士東南技術學院
防災科技研究所
97
The use of non-destructive testing (NDT) techniques for the evaluation of in-service pavement conditions has been widely accepted in the past few decades. Among the available NDT devices, the Falling Weight Deflectometer (FWD) is one of the most popular equipments being used due to its fast testing speed and loading characteristics. The Portable FWD (PFWD), which is a resembled FWD device, was introduced about a decade ago and was mainly utilized to control the soil quality under pavements in the field. This study explored the possibilities of using PFWD to examine the flexible pavement conditions. A series of factors that may affect the use of PFWD data has been performed, such as the loading levels, diameters of the loading plate, pavement temperatures, and the layer thicknesses. The finite element analysis method was employed to evaluate the effects of those factors. Both filed FWD and PFWD test data were analyzed and the comparison of backcalculated layer moduli was carried out. The finite element analysis model showed that the 2-layer pavements may predict the layer moduli better than those of the 3-layer pavements. It was also found that surface layer moduil can be over-estimated if PFWD measurements were used. It was noticed that the loading force and the pavement surface conditions (cracks or rutting) under the loading plate have large effects on the backcalculation of layer moduli. Thus one should pay particular attention when performing the PFWD tests on cracked or rutted pavements to minimize the backcalculation errors.
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Chen, Bo-Ruei, and 陳柏瑞. "Construct the Deflection Correction via Falling Weight Deflectometer at National Freeway." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/vta7tk.
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碩士國立中央大學
土木工程研究所
96
Falling weight deflectometer (FWD) is the most effective and well-developed nondestructive testing equipment and has been used to evaluate the structural capacity and calculate the remaining life of pavements. With Dynatest 8000 FWD of Taiwan Area National Freeway Bureau (MOTC), this study draws a set of field operation guideline, local pavement deflection correction model, and backcalculation procedures appliable to freeways in Taiwan based on the result of field testing. This study constructed a standard test field, including test sections representing Freeway No. 1, No. 3, No. 6, drainage, and stone mastic asphalt (SMA) pavements. Standard FDW operation procedures were developed based local testing experiences, with reference to the LTPP and ASTM standard procedures. Then, the study evaluated several pavement temperature prediction models, and pavement deflection correction model for applicability in Taiwan’s freeway, and found it necessary to develop localized pavement deflection correction model. This study collected 3,302 temperature gradient data during 2007/06 to 2008/06, and 727 deflection statistics from 2007/12 to 2008/3 for analysis. A new temperature prediction model is proposed to accurately predict the effective temperature of pavements. From testing results on freeway, it is found that the deflection correction model based on deflection theory and statistics is fairly applicable to Taiwan. The results of this study provide a useful meansof evaluating pavement structures and can be used in the decision-making of pavement maintenance for National Freeway Bureau.
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Liao, Chi-chou, and 廖啟州. "A Study of the Portable Falling Weight Deflectometer Measured Pavement Modulus." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/94825138068683480613.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
92
Portable Falling Weight Deflectometer (PFWD) was a new tech machine that first applied to monitor pavement structure in this research. To Aim at accuracy, different type of soil, and deflection backcalculated model which established one by one. The results indicated that the variation was smaller than 5% for stress, deflection, and modulus from PFWD, and also proofed that it’s acceptable in accuracy. At different diameter circle plate it also shown when 100mm plate was changed to 300mm diameter plate that the stress and modulus were reduced 88% and 65% respectively. According to the results of soil materials from PFWD and DCP testing, it shown the relationship of modulus in soil materials between PFWD and DCP which indicated PFWD=0.49DCP in sandy clay, PFWD=0.48DCP in gravel soil, PFWD=0.68DCP in sandy soil. The variation of three kinds of soil in DCP and PFWD was about 30~60%. Moreover, utilize PFWD three true deflections to combine the deflections of four assumptions and form FWD deflection blow, it shown the backcalculation of surface layer had 30~50% difference with laboratory. Backcalculation of base and subgrade that had 30~50% differences with DCP. In suggestion, consider the influences of loading and deflections of assumptions to regulate to improve the accuracy of backcalculation. According to the model shown that coefficient R2 is up to 0.77 in DCP and PFWD, it can provide to project personnel for use DCP is tried to get and similar to the base and subgrade resilience modulus of PFWD. Of value to DCP dependability of measuring, need to collect more effective feasibility by way of improving of data achievement in the future.
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Heathcote, Johan Henry. "Towards using the light falling weight deflectometer as a construction control device." Diss., 2016. http://hdl.handle.net/2263/57182.
Full textAbstract:
The Light Falling Weight Deflectometer (LFWD) is a dynamic non-destructive test developed to estimate the in-situ stiffness modulus of pavement materials. The technology of this device is very similar to that of the Falling Weight Deflectometer (FWD) to most closely simulate the loading rate and area of a single moving wheel. The LFWD is a portable scaled down hand operated version of the mechanical electrical FWD that applies an impulse load from a drop weight impacting a circular plate resting on the surface to impose various contact pressures through a calibrated system of rubber buffers. The LFWD, like the FWD, measures both the force and deflections with a velocity transducer to calculate the stiffness of the particular layer.
Over the past decade the LFWD has experienced increased popularity due to the fact that non-destructive tests can be undertaken to determine aspects of a constructed layer s engineering and physical properties and because it is portable. The LFWD would ideally be used to provide better engineering parameters for the quality assurance and quality control during the construction of granular and lightly cemented layers.
Previous LFWD research consists of correlation studies between different strength characterisation testing equipment of pavement layers, there is however, a lot of variability present in these
correlation relationships. One of the most prominent sources of engendering variability within the LFWD measurements is attributed to inconsistent operation protocol.
This study was undertaken to establish an operation protocol for the Dynatest 3031 LFWD device and to consequently investigate the influence of various parameters on the surface moduli and deflection bowl parameters yielded by the LFWD and to determine a reliable relationship between LFWD stiffness results, deflection bowl parameters and other pavement material parameters. The ensuing intention is to accurately predict the model or monitor the basic material characteristics and enhance standard construction quality control testing in a practical engineering quality control application.
LFWD deflection bowl benchmark analysis in conjunction with the calculated surface modulus values can effectively be used as a first step screening tool in identifying areas or zones of distress in a newly constructed pavement layer. The concept of the well-known Red, Amber, Green (RAG) structural condition rating system have been utilised for the LFWD derived deflection bowl parameters and proposed surface moduli ranges for granular base pavements.
This study confirms that the LFWD can be utilised as a non-destructive quality control testing device in a practical engineering quality control application. In spite of the lack of exactness of the current RAG criteria, it had been experienced that such a high sample density non-destructive test method and benchmarking can help identify areas or spots in a constructed layer which warrants additional conventional testing. Additional research is however necessary to continuously improve and revise the proposed ranges in order to achieve accurate and reliable flexible pavement quality and acceptance control procedures for the LFWD device.Die Ligte Vallende Gewig Deflektometer (LVGD) is 'n dinamiese nie-destruktiewe toetsapparaat wat ontwikkel is om die in-situ styfheid modulus van plaveisel materiale te bepaal. Die tegnologie van hierdie toestel is soortgelyk aan dié van die Vallende Gewig Deflektometer (VGD) om die belading en kontakdruk van 'n enkele bewegende wiel akkuraat te simuleer. Die LVGD is 'n draagbare, afgeskaalde handgekontroleerde weergawe van die meganiese elektriese VGD wat 'n impulslas toepas van n vallende gewig op n ronde plaat wat op die oppervlak rus, impakteer om ? kontakdruk oor te dra op die plaveisel deur 'n gekalibreerde stelsel van rubber buffers. Die LVGD, soos die VGD, meet beide die kontakdruk en defleksies met 'n versnellingsmeter om die styfheid van n bepaalde laag te kan bereken. Gedurende die afgelope dekade het die LVGD toenemende gewildheid ervaar te danke aan die feit dat draagbare nie-destruktiewe toetse gedoen kan word om aspekte te bepaal van n gekonstrueerde laag se ingenieurs en fisiese eienskappe. Die LVGD sou ideaal gebruik word om beter ingenieurs-parameters vir die kwalitiet konstruksie kontrole beheer te verskaf tydens die konstruksie van klip en gruis-materiaal en ligte gestabiliseerde plaveisellae. Vorige LVGD navorsing bestaan uit korrelasiestudies tussen verskillende sterkte karakteriserings toetstoerusting van die plaveisellae. Daar is egter baie variasie teenwoordig in hierdie korrelasie verwantskappe. Een van die mees prominente bronne van variasie binne die LVGD meetings word toegeskryf aan teenstrydige operasionele protokol tydens toetsing. Hierdie studie is onderneem om 'n operasionele protokol te vestig vir die Dynatest 3031 LVGD toestel en om gevolglik die invloed van verskeie parameters op die oppervlakmoduli en defleksiekom parameters wat opgelewer word deur die LVGD te ondersoek. Dit het 'n betroubare verhouding tussen LVGD styfheid resultate, defleksiekom parameters en ander plaveisel materiaal parameters daar gestel. Die daaropvolgende voorneme is om die basiese materiaal eienskappe met behulp van 'n model akkuraat te voorspel of te kan moniteer. en om as eerste orde aanduider toetse gebruik te word met standaard konstruksie kontrole beheertoetsing in 'n praktiese ingenieurswese kontrole beheer omgewing. LVGD defleksiekom parameters maatstaf of relatiewe ontleding in samewerking met die berekende oppervlakmodulus waardes kan effektief gebruik word as 'n eerste orde keuringsinstrument in die identifisering van gebiede of sones van swakker materiaal kwaliteit in 'n nuut gekonstrueerde plaveisellaag. Die konsep van die bekende relatiewe maatstaf met Rooi, Amber, Groen (RAG) strukturele toestand graderingstelsel is gebruik, en kriteria voorgestel vir die LVGD afgeleide defleksiekom parameters en voorgestelde oppervlakmoduli vir klip en gruis-materiaal of korrelmateriaal kroonlaag plaveisels se strukturele sterkte evaluering. Hierdie studie bevestig dat die LVGD benut kan word as 'n nie-destruktiewe konstruksiekontrole beheertoetsing apparaat in 'n praktiese konstruksiekontrole beheer omgewing. Ten spyte van die gebrek aan akkuraatheid van die huidige RAG kriteria, is dit ervaar dat so 'n hoë frekwensie toets potensiaal, nie-destruktiewe toets metode kan help om areas of kolle in 'n gekonstrueerde laag te identifiseer wat bykomende konvensionele toetse regverdig. Verdere navorsing is egter noodsaaklik om voortdurend die voorgestelde evalueringskriteria te verbeter en te hersien om akkurate en betroubare buigsame plaveisel kwaliteit en aanvaarding beheer prosedures vir die LVGD toestel daar te stel.
Dissertation (MEng)--University of Pretoria, 2016.
tm2016
Civil Engineering
MEng
Unrestricted
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Wang, Ssu-Tsun, and 王嗣村. "The assessment of strength for a runway using GIS associated the Falling Weight Deflectometer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/91257150580259814855.
Full textAbstract:
碩士立德大學
資源環境研究所
96
Because the powerful of digitally store is a massive and complex spatial data, process them and render them into a readable format for the decision marker′s reference, the Geographic Information System (GIS) has been comprehensively applied in recent years in various fields in order to tackle the problems concerning geographic factors and spatial data. Furthermore, many military and civilian airports and airfields in Taiwan have been operating for quite a long time and some of their pavements on runways are undergoing or going to undergo repaid deterioration. If there is no timely reaction to recover the deteriorating pavements, the airports and airfields might have to shut themselves off to maintain those pavements and their operations might well be adversely affected. Therefore, the survey and maintenance of runways become exceptionally important. The study is focused on the application on the pavement maintenance management system by integrating Falling Weight Deflectometer (FWD) and the GIS and chose an airport to sample its relevant data to verify the application. The analytical results of he FWD survey have shown that through both indexical method and reverse-calculation the structural strength of pavement can be revealed by the GIS and through the spatial analysis, the GIS can effectively locate the inferior areas on the pavement.
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Chou, Min-Hui, and 周明輝. "A Study on the Significance of Calibration and Performance from Pavement Falling Weight Deflectometer." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/27694959495067746381.
Full textAbstract:
碩士中原大學
土木工程研究所
89
The main researches in pavement engineering field in the European and American countries all take resilient modulus, MR as an index on evaluating the structure strength of the pavement and the performance. And the Falling Weight Deflection, FWD instrument can measure the deflection of the pavement directly and recalculate the MR of each layer of the pavement structure. Because of the efficiency of this testing method and can also remain the oneness of the pavement, FWD instrument is now replacing the traditional coring sample method and been wildly used on evaluating the performance and structure strength of the pavement. And this test instrument and method is very helpful to the construction to check and accep, deciding maintain tactic, and overlay pavement design. The first FWD instrument (Dynatest 8000) was involved into the domestic by Taiwan Area National Freeway Bureau 1995, the each sense cell and entire system haven’t been calibrated or evaluate studied until now, therefore the reliability and precision of the measurement result cannot be confirmed. In this study, the calibration work of the sense cells will be done, and compare the results of dynamic backcalculation program ( DBFWD ), static backcalculation program ( WESDEF ), and the MR of the in-situ coring samples and remolded samples, in order to calibrate the general system of the FWD instrument, and also provide a confidence on the reliability of the analysis of evaluating the performance of the pavement by this instrument. According the study results, every sense cell of the instrument still remains stable and precision with a testing procedure recommended by the manufacturer and the standard test method of ASTM D4694-96, and the absolutely calibrate of the velocity gage. And DBFWD program showed a better result of higher reliability and reasonability than WESDEF program, this program is also more suitable for investigation of the open layer of the asphalt concrete and the capacity of the BTB. General speaking, using FWD instrument to investigate the strength of the pavement and predict the life time would be a efficiency, suitable, fast method and the workability is confirmed.
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LAI, J. C., and 賴榮俊. "The Deflection Testing value of Falling Weight Deflectometer in the use of Pavement Maintenance." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/79025557404910675834.
Full text
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Huang, Shu-Fang, and 黃琡芳. "The Study of Input and Information Manage System for Falling Weight Deflectometer Field Survey." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/89141973354262337775.
Full textAbstract:
碩士中原大學
土木工程研究所
90
To meet the continuously construction of the total mileage of the National Freeway system, a better pavement question investigation approach has become necessary. With a new approach that can keep the investigated section intact and fast to perform, the efficiency of whole investigation process can be increased and the impact on traffic and cost to the society can both be lowered. Therefore, the research presents a field investigation information input and management system specially designed for Falling Weight Deflectometer. Research works include the selection of database Management System, the protocol of system transmission, length determination of each investigated section, and development of the Database system. Microsoft ACCESS 2000 was selected to develop platform for the final product. The back ground information for each investigated section (such as beginning/ending stations and others) and corresponding field data readings are the two major parts of the information stored in the database system. In situ, background information of each investigation, current conditions of the investigated pavement and deflection readings from FWD were needed to be entered into the system. For each FWD investigation, the effective range for each test is 5 meters. Considering the significance of random sample, it is recommended by this research that the segment length should be 100 meters for each investigation. If the Pavement Condition Index (PCI) is less than 60, it is recommended that the frequency of investigation have to be increased. In other words, the segment length should be 50 meters instead of 100 meters. PDA (Personal Digital Assistant) is to be used in the field as the information gathering tools. Using USB (Universal Serial Bus), the data between PDA and computer can be synchronized. The conclusions of this research show that the incorporation between the Non-Destructive Deflection Investigation of FWD and the field investigation information input and management system can significantly increase the efficiency of the pavement evaluation.
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Peddibhotla, Sruthi Sree Sravya. "Implementation of a network-level pavement structural condition index based on falling weight deflectometer data." 2010. http://hdl.handle.net/2152/10001.
Full textAbstract:
The Texas Department of Transportation (TxDOT) uses the Pavement Management Information Systems (PMIS) to store and analyze pavement data, and to summarize information needed to support pavement-related decisions. The information on overall condition of the pavement is stored in PMIS, measured with various scores based on visual distress and ride quality surveys. However, a direct measure of the pavement structural condition is currently not in use. A network-level index that can distinguish pavements that require Preventive Maintenance (PM) from those that require Rehabilitation (Rhb) is required, because, it is not cost-effective to apply PM treatments to pavements that are structurally inadequate. The necessity to use an index to improve pavement treatment selection process, especially under financial constraints has motivated this research. The objective of this research is to validate the pavement Structural Condition Index (SCI) developed under a previous Research Project 0-4322, and to develop guidelines for implementing the SCI at the network level.text
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Chen, Chung Wei, and 鐘偉逞. "The Study on Using Falling Weight Deflectometer(FWD) Evaluate Highway Pavement Structure Strength in Taiwan." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/54981656885581845065.
Full textAbstract:
碩士國立中央大學
土木工程研究所
88
The main purpose of using the Falling Weight Deflectometer (FWD), a widely used non-destructive testing equipment, is to evaluate the structural integrity and the bearing capacity of existing pavements. The data measured by FWD can be further analyzed to estimate the remaining life of a pavement and to design the overlay thickness. As such, FWD deflections provide the primary means of making rehabilitation decisions for highway agencies. The JILS-20 FWD was employed in this study for the evaluation of pavement conditions. The major goal is to develop a localized pavement evaluation model based on the characteristics of the testing equipment with the environmental conditions in Taiwan. FWD tests were performed on a standard pavement test section built in this study. The deflection correction model was developed based on FWD measurements using regression analysis with three prime affecting variables; the pavement temperature, the pavement thickness, and the test load. This deflection correction model was further verified to develop a pavement strength evaluation model using FWD data collected from in-service pavements together with site conditions observed by pavement engineers and the applications of backcalculation analysis. Unlike other researches using solely numerical methods for model development, this study used in-situ data to derive the pavement strength evaluation model. As a result, a localized pavement strength evaluation model using FWD deflections can be practically achieved.
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Liu, Jung, and 劉蓉. "The Back-Calculation Analysis of Falling Weight Deflectometer and the Development of Temperature Evaluation Model for Asphalt Pavement." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e8x42j.
Full textAbstract:
碩士國立中興大學
土木工程學系所
107
The Falling Weight Deflectometer (FWD) is a non-destructive test (NDT) and has been used to evaluate the structural capacity and calculate the remaining life of pavements. It is used to measure the deflection when each measuring point on the road surface is subjected to an impact load. According to the measured deflection, carry out back-calculation analysis to obtain the structural strength of each layer of the road. However, the strength of the asphalt material layer is affected by temperature. Hence, the strength of the asphalt material layer needs to be corrected by temperature, and the FWD test back-calculation analysis results at different temperatures are corrected to the same temperature to evaluation the strength of the asphalt material under the same standard. In addition, the temperature prediction mode of each depth of the road is needed to evaluate the temperature of each depth of the road, due to the temperature of each depth of the existing road is difficult to measure. This study first analyzes the temperature data collected at the FWD standard test field in Nantou, Taiwan and establishes a temperature prediction model. Then, in order to determine the relationship between the temperature and the shift factor of the asphalt material, a dynamic modulus test is performed in the laboratory, and the FWD test is also carried out and back-calculated. The back-calculated asphalt layer strength was corrected by the temperature shift factor and compared with the dynamic modulus test results. According to the comparison between back-calculation of asphalt material layer and dynamic modulus test and the back-calculation results of the base layer of each section, it can be seen that the FWD test can effectively distinguish the structural strength of different layers of the road, and the temperature-corrected asphalt material layer strength and laboratory test results have Highly correlated. Furthermore, the depth temperature prediction model proposed by the Institute can effectively predict the temperature of each depth in the road structure in Taiwan. Compared with the actual measured temperature, the correlation coefficient is as high as 90% at the road depth of 5.5 cm, and it is also more than 82% at the road depth of 24.5 cm. The slope falls within 1±0.05, which confirms that the model temperature is close to the actual measured temperature.