• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8
  • 3
  • 1
  • Tagged with
  • 15
  • 15
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Geotextile separators for dust suppression on gravel roads

Freeman, Elisabeth A. January 2006 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 7, 2007) Includes bibliographical references.
2

The formulation and application of a gravel loss model in management of gravel roads in Iringa region, Tanzania

Mwaipungu, Richard Robert January 2015 (has links)
Submitted in fulfillment of the academic requirements for the degree of Doctor of Engineering: Civil Engineering and Surveying, Durban University of Technology. Durban. South Africa, 2015. / Among various gravel roads distress prediction models in existence, a gravel loss prediction model is considered critical in selecting the optimal re-gravelling schedule for effective maintenance management of gravel roads. However, due to the number of variables contributing to deterioration of gravel roads and hence gravel loss, gravel loss prediction models are not readily transferable from one geographical location to another, particularly if the locations in question differ in climatic condition, gravel material characteristics, quality of construction and maintenance, terrain, traffic characteristics and driver behaviours. Addressing the aforementioned local characteristics pose a challenge to existing international gravel loss prediction models when employed locally, resulting in inaccurate prediction of gravel loss. Hence the need for a gravel loss prediction model to be formulated locally so as to address local characteristics influencing gravel roads deterioration. The main objective of this study was to formulate locally, a statistically accurate gravel loss prediction model for marginal gravel materials employed to surface gravel roads in Iringa region. The intention was to address local characteristics influencing gravel roads deterioration in the region. To promote research on gravel roads management, the author has published seven papers and presented ten papers in established journals and conferences respectively, as indicated in the Appendix 13. It is author expectation that, given the right impetus, locally formulated gravel loss prediction models can be incorporated, as one of a tool, in gravel roads management systems (GRMS). The literature review focused on the gravel road condition surveys, modelling exercises, gravel loss, and a review of existing gravel loss prediction models. The literature review also examined the version of GRMS currently practiced in Tanzania by its road organizations. The study used factorial experimental design. Parameters which are deemed to influence the gravel loss were collected and studied. A questionnaire was used to study the status of gravel road MMS in Tanzania. The data obtained from the questionnaire responses were analysed with the aid of Statistical Package for Social Sciences (SPSS) and Microsoft Excel. A detailed gravel road condition survey of each 300 m long test section was carried out during site visits. The measurement of gravel loss through the change in average height loss formed a crucial part of the study. The modelling of a gravel loss prediction model was performed using pavemetric principles, the term coined by this study, which is principally based on econometric principles. From the analysis of questionnaire responses, it was evident that each Tanzania Roads Agency (TANROADS) regional office and district council works department needs to have a unique MMS and GRMS which reflect their operating capacity. The results of the condition survey led to the formulation of a new range of grading coefficient (GC) to suit the local marginal materials. The gravel loss survey results assisted in establishing gravel loss thresholds. The thresholds were based on the rate of gravel loss noted in the study. These thresholds can be employed to enhance the quality control of gravel roads construction and maintenance practices. The study formulated a gravel loss prediction model for Iringa region. The process utilized average daily traffic, climate, and derivatives of sieve analysis and Atterberg limits. The model is statistically significant at 1 % level. The model gives a constant gravel loss of 0.1 mm per annum regardless the state of the six variables in the model. This was attributed to autonomous loss that is the amount of gravel material lost through mechanical and chemical weathering. Recommendations include the need for gravel loss prediction models to reflect local characteristics influencing the deterioration of the gravel roads in question and the modelling capacity of local road agencies. Areas for further studies are highlighted.
3

Comparison of various types of road surfacing

Tevis, Charles Cyrus. January 1935 (has links) (PDF)
Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1935. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed June 9, 2010) Includes bibliographical references (p. 36) and index (p. 37).
4

Guidelines for determining the most economical roadway surface type for local rural roads

Patel, Himanshu S. January 1900 (has links)
Master of Science / Civil Engineering / Sunanda Dissanayake / The percentage of gravel roads in rural areas in Kansas is higher than most states. A wide variation of traffic volumes across different regions and variations of local conditions and scenarios present a great challenge for local agencies to determine suitable roadway surface types for local rural roads, especially considering constraints on transportation budgets. The primary objective of this research was developing specific guidelines to identify the most suitable roadway surface for a particular roadway section with given conditions. Surveys were carried out to determine the importance of factors affecting the selection of a roadway surface type, where were later used for guideline development. General guidelines were developed using the multi-criteria assessment method in order to fulfill the main objective. The main important factors in decision-making were identified as agency cost, safety, Vehicle Operating Cost (VOC), traffic volume, purpose of road usage, and public preference. Multi-criteria assessment method involves calculating the weights for the factors important in decision-making, the respective scaled values for each factor for paved surface and gravel surface, and eventually calculating the final score for paved and gravel surface type. Equations were formulated to carry out life cycle cost (LCC) analysis along with the present worth evaluation. The formulas provided flexibility to calculate agency cost by considering local variation. VOC was calculated for paved and gravel roads considering variations in speed of different classes of vehicles, gradient and horizontal curve of the road, and the conversion factor for cost on paved surface versus gravel surface. Safety analysis was carried out for local rural roads in Kansas for five years, from 2010 to 2014, using the Kansas Department of Transportation’s KCARS database. After calculating the EPDO crash rates on paved and gravel roads in Kansas, results showed that paved surfaces were in general safer than gravel surfaces, which was taken into consideration while calculating the scaled values for safety. The final score was calculated by multiplying the weights of each factor and their respective scaled values. Roadway surface type with higher score is the preferred alternative for a road section under consideration. A computer-based program was created as a user interface, using Visual Studio, to carry out all complex calculations for determining LCC and VOC considering local variations. The program also helped determine final total scores for paved and gravel roads by considering scaled values of all-important factors considered for conversion. Another approach using cost versus traffic volume showed that the break-even point for traffic volume decreased with an increased percentage of trucks and increased vehicle speeds. Thus, the developed guideline helps determine the best roadway surface type for any set of local conditions.
5

Reducing sediment production from forest roads during wet-weather use /

Toman, Elizabeth Myers. January 2007 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.
6

The Spatial Effects of Road Use Intensity on Forest Plant Communities and Soil Chemistry

Asmussen, David 19 July 2011 (has links)
Roads alter the ecological landscape and affect the function and composition of nearby soil chemistry and plant communities in an area of impact termed the “edge-effect zone”. While the 6.3 million kilometers of roads in the US cover only about 1% of the land, the edge effect zone around these roads has been estimated to occupy nearly 20% of the total land area in the US (Forman 2000). The objective of this study was to examine the spatial extent of transported materials and impacts on forest soil and vegetative communities immediately surrounding roadways based on road types classified as “Highway,” “Two-Lane Paved,” and “Gravel.” This research was located within two watersheds in the state of Vermont, in areas where a substantial area of forest existed adjacent the roadway. Using GIS mapping, transects were constructed at right angles to the road, and samples were gathered at the Shoulder, Ditch, Backslope, 10m from the edge of the forest, and 50m from road center during the summer of May 2009 to August 2009. Soil samples were analyzed for a suite of nutrients and physical characteristics, as well as heavy metals. The forest composition and percent area coverage by species of herbaceous flora and woody shrubs were also recorded. The main effects from roads were dependent on the extent of clearing and topography modification required for a roadway. The spatial extent of these modifications was correlated positively with road use intensity. Highways have the greatest ecological impact and gravel roads the least impact. The cleared area defines how much sunlight is available to plant communities and the distance that road pollutants will travel. Some heavy metals (such as Pb, Cd, Ni and Zn) were correlated positively with road use intensity. Gravel roads have higher calcium content in nearby soil when compared to other road types. This is most likely due to mobilized dust from the road base. Proximity to all road types had neutralizing effects on the soil pH relative to the acidic native forest soil. Changes in microtopography next to the road have marked effects on the composition of plant communities through maintenance and direction of water flow. Ditch areas support wetland plants, and have greater soil moisture and sulfur content, while plant communities closer to the road are characteristic of drier upland zones. The area past the edge of the forest does not appear to be affected chemically or physically by any of the road types, possibly due to the dense vegetation that develops outside of the right-of-way. To reduce the ecological footprint of future road development, road corridors should be narrowed, traffic consolidated to mass transit systems such as busses or railroad, and buffer zones of vegetation next to the right-ofway should be encouraged to contain the spread of pollutants.
7

Identificação e discussão dos mecanismos de degradação de pavimentos com revestimento primário / Identification and discussion on distress mechanisms of unsurfaced gravel roads

Nervis, Leandro Olivio January 2016 (has links)
As rodovias com revestimento primário constituem a imensa maioria da extensão da malha viária do Brasil e de muitos países. Sua manutenção em um nível mínimo aceitável de serventia consome parcelas importantes de orçamentos governamentais. Contudo, na maioria das vezes, as atividades de implantação e manutenção têm escasso sucesso, porque os agentes encarregados desconhecem a tecnologia específica. Visando contribuir para práticas mais efetivas, esta tese analisa os resultados de uma pesquisa realizada com o objetivo de identificar e discutir os mecanismos de degradação de rodovias com revestimento primário, à luz das Mecânicas dos Solos e dos Pavimentos. O projeto experimental incluiu ensaios laboratoriais, bem como a construção e monitoramento de desempenho, ao longo de 30 meses, de um pavimento experimental, em projeto de assentamento da Reforma Agrária, no Rio Grande do Sul. O revestimento primário foi construído em duas camadas (a superior constituída por 7 cm de saibro e a inferior por 17 cm de argila laterítica) assentes sobre um subleito estratificado, com camada superior arenosa. As formações geológicas são constituídas por depósitos aluvionares (subleito) e por siltito (jazida de argila) e gnaisse (jazida do saibro). A compactação das camadas foi verificada por meio de ensaios clássicos e com emprego do cone de penetração dinâmica (DCP). As deflexões foram medidas no topo do subleito e sobre cada camada de revestimento, com utilização de viga Benkelman. Amostras deformadas dos materiais do revestimento primário e da camada superior do subleito foram coletadas. Em laboratório realizaram-se ensaios de caracterização, bem como da classificação MCT; foram avaliadas a resistência ao desgaste e a durabilidade da fração graúda do saibro (abrasão Los Angeles e alteração de rochas água-estufa). Realizaram-se ensaios de compactação, Índice de Suporte Califórnia, Inderbitzen (erodibilidade), cisalhamento direto e triaxiais de carga repetida, para obtenção de módulos de resiliência e avaliação do comportamento quanto à deformação permanente. Complementarmente, foram obtidas curvas de retenção de água. Com base nos resultados laboratoriais foram realizadas previsões de desempenho do pavimento experimental, fundamentadas em conceitos, prescrições e em modelos matemáticos e estatísticos encontrados na literatura e no emprego do programa HDM 4. Durante o período de monitoramento do pavimento experimental foram realizados 3 levantamentos para a obtenção da Irregularidade Longitudinal (IRI), com o emprego de um perfilômetro inercial e 4 inspeções para a avaliação da evolução dos principais defeitos típicos de pavimento com revestimento primário. Os defeitos observados foram: afundamento de trilha de roda, buracos, perda de abaulamento, perda de espessura de revestimento e sulcos de erosão; identificando-se e discutindo-se os mecanismos de degradação a eles associados. Também foram comparadas as previsões de desempenho com a evolução da serventia do pavimento experimental, constatando-se que os modelos apresentados na literatura internacional nem sempre apresentam acurácia satisfatória. Isto mostra a necessidade de se desenvolverem novos modelos e calibrar os existentes, como condição indispensável para otimizar as atividades de manutenção das rodovias com revestimento primário. / Most of Brazilian and other countries’ roads networks mainly comprise unsurfaced gravel roads. The maintenance of such roads at a minimum acceptable level of serviceability consumes large percentages of governs budgets. In spite of that, the construction and maintenance activities are scarcely well-succeeded, since the personnel involved do not know the specific technology. Aiming at contributing for more effective practices, this thesis analyses the results of a research carried out with the objective of identifying and discussing distress mechanisms of unsurfaced gravel roads, based on Soil and Pavement Mechanics. Experimental procedures included laboratory tests, as well as the construction and performance monitoring, along 30 months, of a test section, in an agrarian reform settlement, in Rio Grande do Sul state, southern Brazil. The wearing course of the unsurfaced pavement consisted of two different layers (a 7-cm-thick upper layer, made of genuine residual soil and a lower one with 17 cm of lateritic clay), built over a stratified subgrade, with a sandy upper layer. Geological formations consisted of alluvial fans (the subgrade), siltstone (the clay site) and gneiss (genuine residual soil site). Layers compaction was quantified by means of classic tests and also using the dynamic cone penetrometer (DCP). Using a Benkelman beam, surface deflections were measured on the top of the subgrade and every layer. Samples were taken from the subgrade and from both materials that constitute the wearing course, in order to perform laboratory tests of characterization and those of a Brazilian soils classification system, known as MCT (miniature, compacted, tropical). Los Angeles abrasion and rock alteration by wetting and drying tests were done on samples of the genuine residual soil coarse fraction. Every material was subjected to compaction, CBR, Inderbitzen (erodibility), direct shear and repeated loading triaxial tests (these latter to compute resilient moduli and to evaluate the permanent deformation behaviour). Besides, water-retention curves were obtained. Based on laboratory results, the performance of the experimental pavement was predicted, founded on concepts, materials prescriptions and mathematical and statistical models and using HDM 4 program. During the monitoring period three roughness (IRI) surveys were carried out, using an inertial profilometer. Four distresses surveys were carried out to evaluate the evolution of the most important distresses typical of unsurfaced gravel roads. Distresses as rutting, potholes, cross-section deformation and thickness reduction and erosion channels were observed and the associated distress mechanisms were discussed. Pavement performance predictions were compared to the measured serviceability evolution. It was found out that the models available in the literature not always yield accurate results. Because of that, developing new models and calibrating the existing ones is mandatory to optimize maintenance activities in unsurfaced gravel roads.
8

Identificação e discussão dos mecanismos de degradação de pavimentos com revestimento primário / Identification and discussion on distress mechanisms of unsurfaced gravel roads

Nervis, Leandro Olivio January 2016 (has links)
As rodovias com revestimento primário constituem a imensa maioria da extensão da malha viária do Brasil e de muitos países. Sua manutenção em um nível mínimo aceitável de serventia consome parcelas importantes de orçamentos governamentais. Contudo, na maioria das vezes, as atividades de implantação e manutenção têm escasso sucesso, porque os agentes encarregados desconhecem a tecnologia específica. Visando contribuir para práticas mais efetivas, esta tese analisa os resultados de uma pesquisa realizada com o objetivo de identificar e discutir os mecanismos de degradação de rodovias com revestimento primário, à luz das Mecânicas dos Solos e dos Pavimentos. O projeto experimental incluiu ensaios laboratoriais, bem como a construção e monitoramento de desempenho, ao longo de 30 meses, de um pavimento experimental, em projeto de assentamento da Reforma Agrária, no Rio Grande do Sul. O revestimento primário foi construído em duas camadas (a superior constituída por 7 cm de saibro e a inferior por 17 cm de argila laterítica) assentes sobre um subleito estratificado, com camada superior arenosa. As formações geológicas são constituídas por depósitos aluvionares (subleito) e por siltito (jazida de argila) e gnaisse (jazida do saibro). A compactação das camadas foi verificada por meio de ensaios clássicos e com emprego do cone de penetração dinâmica (DCP). As deflexões foram medidas no topo do subleito e sobre cada camada de revestimento, com utilização de viga Benkelman. Amostras deformadas dos materiais do revestimento primário e da camada superior do subleito foram coletadas. Em laboratório realizaram-se ensaios de caracterização, bem como da classificação MCT; foram avaliadas a resistência ao desgaste e a durabilidade da fração graúda do saibro (abrasão Los Angeles e alteração de rochas água-estufa). Realizaram-se ensaios de compactação, Índice de Suporte Califórnia, Inderbitzen (erodibilidade), cisalhamento direto e triaxiais de carga repetida, para obtenção de módulos de resiliência e avaliação do comportamento quanto à deformação permanente. Complementarmente, foram obtidas curvas de retenção de água. Com base nos resultados laboratoriais foram realizadas previsões de desempenho do pavimento experimental, fundamentadas em conceitos, prescrições e em modelos matemáticos e estatísticos encontrados na literatura e no emprego do programa HDM 4. Durante o período de monitoramento do pavimento experimental foram realizados 3 levantamentos para a obtenção da Irregularidade Longitudinal (IRI), com o emprego de um perfilômetro inercial e 4 inspeções para a avaliação da evolução dos principais defeitos típicos de pavimento com revestimento primário. Os defeitos observados foram: afundamento de trilha de roda, buracos, perda de abaulamento, perda de espessura de revestimento e sulcos de erosão; identificando-se e discutindo-se os mecanismos de degradação a eles associados. Também foram comparadas as previsões de desempenho com a evolução da serventia do pavimento experimental, constatando-se que os modelos apresentados na literatura internacional nem sempre apresentam acurácia satisfatória. Isto mostra a necessidade de se desenvolverem novos modelos e calibrar os existentes, como condição indispensável para otimizar as atividades de manutenção das rodovias com revestimento primário. / Most of Brazilian and other countries’ roads networks mainly comprise unsurfaced gravel roads. The maintenance of such roads at a minimum acceptable level of serviceability consumes large percentages of governs budgets. In spite of that, the construction and maintenance activities are scarcely well-succeeded, since the personnel involved do not know the specific technology. Aiming at contributing for more effective practices, this thesis analyses the results of a research carried out with the objective of identifying and discussing distress mechanisms of unsurfaced gravel roads, based on Soil and Pavement Mechanics. Experimental procedures included laboratory tests, as well as the construction and performance monitoring, along 30 months, of a test section, in an agrarian reform settlement, in Rio Grande do Sul state, southern Brazil. The wearing course of the unsurfaced pavement consisted of two different layers (a 7-cm-thick upper layer, made of genuine residual soil and a lower one with 17 cm of lateritic clay), built over a stratified subgrade, with a sandy upper layer. Geological formations consisted of alluvial fans (the subgrade), siltstone (the clay site) and gneiss (genuine residual soil site). Layers compaction was quantified by means of classic tests and also using the dynamic cone penetrometer (DCP). Using a Benkelman beam, surface deflections were measured on the top of the subgrade and every layer. Samples were taken from the subgrade and from both materials that constitute the wearing course, in order to perform laboratory tests of characterization and those of a Brazilian soils classification system, known as MCT (miniature, compacted, tropical). Los Angeles abrasion and rock alteration by wetting and drying tests were done on samples of the genuine residual soil coarse fraction. Every material was subjected to compaction, CBR, Inderbitzen (erodibility), direct shear and repeated loading triaxial tests (these latter to compute resilient moduli and to evaluate the permanent deformation behaviour). Besides, water-retention curves were obtained. Based on laboratory results, the performance of the experimental pavement was predicted, founded on concepts, materials prescriptions and mathematical and statistical models and using HDM 4 program. During the monitoring period three roughness (IRI) surveys were carried out, using an inertial profilometer. Four distresses surveys were carried out to evaluate the evolution of the most important distresses typical of unsurfaced gravel roads. Distresses as rutting, potholes, cross-section deformation and thickness reduction and erosion channels were observed and the associated distress mechanisms were discussed. Pavement performance predictions were compared to the measured serviceability evolution. It was found out that the models available in the literature not always yield accurate results. Because of that, developing new models and calibrating the existing ones is mandatory to optimize maintenance activities in unsurfaced gravel roads.
9

Identificação e discussão dos mecanismos de degradação de pavimentos com revestimento primário / Identification and discussion on distress mechanisms of unsurfaced gravel roads

Nervis, Leandro Olivio January 2016 (has links)
As rodovias com revestimento primário constituem a imensa maioria da extensão da malha viária do Brasil e de muitos países. Sua manutenção em um nível mínimo aceitável de serventia consome parcelas importantes de orçamentos governamentais. Contudo, na maioria das vezes, as atividades de implantação e manutenção têm escasso sucesso, porque os agentes encarregados desconhecem a tecnologia específica. Visando contribuir para práticas mais efetivas, esta tese analisa os resultados de uma pesquisa realizada com o objetivo de identificar e discutir os mecanismos de degradação de rodovias com revestimento primário, à luz das Mecânicas dos Solos e dos Pavimentos. O projeto experimental incluiu ensaios laboratoriais, bem como a construção e monitoramento de desempenho, ao longo de 30 meses, de um pavimento experimental, em projeto de assentamento da Reforma Agrária, no Rio Grande do Sul. O revestimento primário foi construído em duas camadas (a superior constituída por 7 cm de saibro e a inferior por 17 cm de argila laterítica) assentes sobre um subleito estratificado, com camada superior arenosa. As formações geológicas são constituídas por depósitos aluvionares (subleito) e por siltito (jazida de argila) e gnaisse (jazida do saibro). A compactação das camadas foi verificada por meio de ensaios clássicos e com emprego do cone de penetração dinâmica (DCP). As deflexões foram medidas no topo do subleito e sobre cada camada de revestimento, com utilização de viga Benkelman. Amostras deformadas dos materiais do revestimento primário e da camada superior do subleito foram coletadas. Em laboratório realizaram-se ensaios de caracterização, bem como da classificação MCT; foram avaliadas a resistência ao desgaste e a durabilidade da fração graúda do saibro (abrasão Los Angeles e alteração de rochas água-estufa). Realizaram-se ensaios de compactação, Índice de Suporte Califórnia, Inderbitzen (erodibilidade), cisalhamento direto e triaxiais de carga repetida, para obtenção de módulos de resiliência e avaliação do comportamento quanto à deformação permanente. Complementarmente, foram obtidas curvas de retenção de água. Com base nos resultados laboratoriais foram realizadas previsões de desempenho do pavimento experimental, fundamentadas em conceitos, prescrições e em modelos matemáticos e estatísticos encontrados na literatura e no emprego do programa HDM 4. Durante o período de monitoramento do pavimento experimental foram realizados 3 levantamentos para a obtenção da Irregularidade Longitudinal (IRI), com o emprego de um perfilômetro inercial e 4 inspeções para a avaliação da evolução dos principais defeitos típicos de pavimento com revestimento primário. Os defeitos observados foram: afundamento de trilha de roda, buracos, perda de abaulamento, perda de espessura de revestimento e sulcos de erosão; identificando-se e discutindo-se os mecanismos de degradação a eles associados. Também foram comparadas as previsões de desempenho com a evolução da serventia do pavimento experimental, constatando-se que os modelos apresentados na literatura internacional nem sempre apresentam acurácia satisfatória. Isto mostra a necessidade de se desenvolverem novos modelos e calibrar os existentes, como condição indispensável para otimizar as atividades de manutenção das rodovias com revestimento primário. / Most of Brazilian and other countries’ roads networks mainly comprise unsurfaced gravel roads. The maintenance of such roads at a minimum acceptable level of serviceability consumes large percentages of governs budgets. In spite of that, the construction and maintenance activities are scarcely well-succeeded, since the personnel involved do not know the specific technology. Aiming at contributing for more effective practices, this thesis analyses the results of a research carried out with the objective of identifying and discussing distress mechanisms of unsurfaced gravel roads, based on Soil and Pavement Mechanics. Experimental procedures included laboratory tests, as well as the construction and performance monitoring, along 30 months, of a test section, in an agrarian reform settlement, in Rio Grande do Sul state, southern Brazil. The wearing course of the unsurfaced pavement consisted of two different layers (a 7-cm-thick upper layer, made of genuine residual soil and a lower one with 17 cm of lateritic clay), built over a stratified subgrade, with a sandy upper layer. Geological formations consisted of alluvial fans (the subgrade), siltstone (the clay site) and gneiss (genuine residual soil site). Layers compaction was quantified by means of classic tests and also using the dynamic cone penetrometer (DCP). Using a Benkelman beam, surface deflections were measured on the top of the subgrade and every layer. Samples were taken from the subgrade and from both materials that constitute the wearing course, in order to perform laboratory tests of characterization and those of a Brazilian soils classification system, known as MCT (miniature, compacted, tropical). Los Angeles abrasion and rock alteration by wetting and drying tests were done on samples of the genuine residual soil coarse fraction. Every material was subjected to compaction, CBR, Inderbitzen (erodibility), direct shear and repeated loading triaxial tests (these latter to compute resilient moduli and to evaluate the permanent deformation behaviour). Besides, water-retention curves were obtained. Based on laboratory results, the performance of the experimental pavement was predicted, founded on concepts, materials prescriptions and mathematical and statistical models and using HDM 4 program. During the monitoring period three roughness (IRI) surveys were carried out, using an inertial profilometer. Four distresses surveys were carried out to evaluate the evolution of the most important distresses typical of unsurfaced gravel roads. Distresses as rutting, potholes, cross-section deformation and thickness reduction and erosion channels were observed and the associated distress mechanisms were discussed. Pavement performance predictions were compared to the measured serviceability evolution. It was found out that the models available in the literature not always yield accurate results. Because of that, developing new models and calibrating the existing ones is mandatory to optimize maintenance activities in unsurfaced gravel roads.
10

Information needs of gravel roads stakeholders :  A case study to elicit the requirements of future users of a cloud-based information system

Abbas, Nada January 2020 (has links)
Within any ecosystem, information needs are shared to be fulfilled and to support the ecosystem in a way or another. They are vital for designing appropriate information systems that will provide those needs. In this thesis, the gravel road ecosystem is studied, where efficient information sharing is not enabled due to the lack of appropriate information systems. Thus,when focusing on the gravel roads ecosystem, information plays a crucial role regarding the maintenance acts upon these roads. Moreover, not enough literature investigates theinformation needs of gravel roads stakeholders with the aim to improve the maintenance ofthese roads. Therefore, this thesis intends to elicit information needs of gravel road stakeholders by performing an exploratory case study. The case study forms a part of an ongoing project with the goal to build a cloud-based information system for a sustainable gravel road maintenance. Data were collected through telephone- and online-based interviews with several key stakeholders in Sweden and were thereafter structured through template analysis. The major findings were a set of information needs and several needed sensors within the pre-mentioned information system. This thesis concluded that the future cloud-based information system in the ongoing project is a useful system for sharing vital information among future gravel roads stakeholders, considering the variety of needed information that affects the maintenance of the gravel roads. / Sustainable maintenance of gravel roads

Page generated in 0.0491 seconds