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Mechanistic Modeling Of Unbound Granular Materials
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Book Synopsis Mechanistic Modeling of Unbound Granular Materials by : Bereket Yohannes
Download or read book Mechanistic Modeling of Unbound Granular Materials written by Bereket Yohannes and published by . This book was released on 2009 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several tests are used for characterizing unbound granular materials for pavement applications. The California Bearing Ratio (CBR), resilient modulus (MR), Dynamic Cone Penetrometer (DCP) tests are three of the most common tests used for this purpose. The objective of this research is twofold. The first is to develop numerical models for these three tests. The second is to investigate relationship between basic material properties, boundary conditions, and test results, ultimately, to develop a physics-based correlation between these tests. A 3-D discrete element method (DEM) based model is adapted to simulate these tests. Good agreement is observed between the results of the simulations and sample numerical and experimental studies on granular materials. The DEM code is used to determine effects of aggregate shape, coefficient of friction, gradation, stiffness and other details on test results. The model is also used to investigate statistics of inter-particle interaction between the granular particles.
Book Synopsis Mechanistic Characterization of Unbound Granular Materials by : Bereket Yohannes Tewoldebrhan
Download or read book Mechanistic Characterization of Unbound Granular Materials written by Bereket Yohannes Tewoldebrhan and published by . This book was released on 2008 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Structural Material Model for Granular Bases by :
Download or read book A Structural Material Model for Granular Bases written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Techniques typically used in mechanistic analyses to characterize the behavior of unbound granular materials in a flexible pavement often predict stress conditions exceeding the material's static strength. Some pavement analysis tools such as ILLI-PAVE attempt to adjust predicted stresses in unbound layers so that they do not violate the Mohr-Coulomb failure envelope. However, the adjusted stresses are used only to calculate the resilient modulus to be used in the next iteration of the model, resulting in final stresses that are questionable and that frequently exceed the material's strength. Laboratory resilient modulus tests were conducted on granular at stress states exceeding the material's static shear strengths. Based on the data obtained, a material model for unbound granular material was developed that is a modification of the commonly used k-theta-n model for unbound granular materials. In addition, an advantage of the modified model is the ability to analyze the structural effects of granular materials having different shear strength characteristics. For the covering abstract of this conference see IRRD number 872978.
Book Synopsis Unbound Granular Materials by : A. Gomes Correia
Download or read book Unbound Granular Materials written by A. Gomes Correia and published by . This book was released on 1999 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mathematical Modeling in Mechanics of Granular Materials by : Oxana Sadovskaya
Download or read book Mathematical Modeling in Mechanics of Granular Materials written by Oxana Sadovskaya and published by Springer Science & Business Media. This book was released on 2012-06-08 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph contains original results in the field of mathematical and numerical modeling of mechanical behavior of granular materials and materials with different strengths. It proposes new models helping to define zones of the strain localization. The book shows how to analyze processes of the propagation of elastic and elastic-plastic waves in loosened materials, and constructs models of mixed type, describing the flow of granular materials in the presence of quasi-static deformation zones. In a last part, the book studies a numerical realization of the models on multiprocessor computer systems. The book is intended for scientific researchers, lecturers of universities, post-graduates and senior students, who specialize in the field of the deformable materials mechanics, mathematical modeling and adjacent fields of applied and calculus mathematics.
Book Synopsis Advances in Transportation Geotechnics by : Ed Ellis
Download or read book Advances in Transportation Geotechnics written by Ed Ellis and published by CRC Press. This book was released on 2008-08-01 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: Highways provide the arteries of modern society. The interaction of road, rail and other transport infrastructure with the ground is unusually intimate, and thus needs to be well-understood to provide economic and reliable infrastructure for society. Challenges include not only the design of new infrastructure (often on problematic ground), but inc
Book Synopsis Pavements Unbound by : Andrew Dawson
Download or read book Pavements Unbound written by Andrew Dawson and published by CRC Press. This book was released on 2014-09-01 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nearly all highway, airport, dock and industrial pavements contain large quantities of untreated aggregate in the form of unbound pavement layers. In many pavements, which are lightly or moderately trafficked, crushed rock or gravel derived aggregates comprise the majority of the construction or, in the case of unsealed pavements, all of the structure. This book provides studies of the performance and description of this material that will help the reader to better understand its characteristics and behaviour both alone and as part of the pavement structure it forms. This work will be useful to practitioners, policy makers, researchers and students. It forms a sequel to the earlier book "Unbound Aggregates in Road Construction" also published by Balkema
Book Synopsis Modelling of the Resilient and Permanent Deformation Behaviour of Subgrade Soils and Unbound Granular Materials by : Haithem Soliman
Download or read book Modelling of the Resilient and Permanent Deformation Behaviour of Subgrade Soils and Unbound Granular Materials written by Haithem Soliman and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laboratory characterization of subgrade soils and unbound granular materials is an essential component of the Mechanistic-Empirical Pavement Design Guide (Pavement ME). The design thickness and performance of a pavement structure are highly dependent on the deformation behaviour of subgrade and granular material. Specifications for granular materials vary among transportation agencies based on the availability of materials, climatic conditions, and function. Specifications aim to provide durable materials that meet design requirements and achieve the target design life with cost effective materials. The objectives of the research are to: • evaluate resilient modulus of typical fine-grained soils under traffic loading. • evaluate resilient modulus, permanent deformation, and permeability of typical unbound granular materials. • evaluate the effect of moisture and fines fraction on the performance of unbound granular materials and subgrade soil. • develop prediction models for resilient modulus to improve reliability of Level 2 inputs in the Pavement ME. • provide test data in support of updating Manitoba Infrastructure and Transportation specifications for unbound granular materials to improve the performance of pavement structures. Resilient modulus tests were conducted on three types of subgrade soil (high plastic clay, sandy clay, and silty sand/sandy silt) at four levels of moisture content. Resilient modulus, permanent deformation and permeability tests were conducted on six gradations representing two types of granular material (100% crushed limestone and gravel) at two levels of moisture content. Prediction models were developed for resilient modulus and compared to the models developed under the Long Term Pavement Performance program. The proposed models provided more reliable predictions with lower root mean square error. The deformation behaviour of the granular materials was classified according to the shakedown and dissipated energy approaches. Among the tested fines contents, limestone and gravel materials with optimum fines contents of 4.5% and 9%, respectively, had better resistance to plastic deformation and higher resilient modulus. The dissipated energy approach can be used to determine the stress ratio for the boundary between post compaction and stable zones from multistage triaxial testing. Result of permeability tests showed that the hydraulic conductivity of unbound granular material increased as the fines content decreased.
Book Synopsis Geotechnics for Transportation Infrastructure by : Ravi Sundaram
Download or read book Geotechnics for Transportation Infrastructure written by Ravi Sundaram and published by Springer. This book was released on 2019-05-30 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents selected papers from the International Symposium on Geotechnics for Transportation Infrastructure (ISGTI 2018). The research papers cover geotechnical interventions for the diverse fields of policy formulation, design, implementation, operation and management of the different modes of travel, namely road, air, rail and waterways. This book will be of interest to academic and industry researchers working in transportation geotechnics, as also to practicing engineers, policy makers, and civil agencies.
Book Synopsis Estimating Stiffness of Subgrade and Unbound Materials for Pavement Design by : Anand J. Puppala
Download or read book Estimating Stiffness of Subgrade and Unbound Materials for Pavement Design written by Anand J. Puppala and published by Transportation Research Board. This book was released on 2008 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: At head of title: National Cooperative Highway Research Program.
Book Synopsis Mechanistic Model to Predict the Impact of the Aggregate Matrix on the Permanent Deformation of Asphalt Mixtures by : Samer Hassan Dessouky
Download or read book Mechanistic Model to Predict the Impact of the Aggregate Matrix on the Permanent Deformation of Asphalt Mixtures written by Samer Hassan Dessouky and published by . This book was released on 2005 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot mix asphalt (HMA) is a granular composite material stabilized by the presence of asphalt binder. The behavior of HMA is highly influenced by the microstructure distribution in terms of the different aggregate particles present in the mix, the directional distribution of aggregates, the distribution of voids, and the nucleation and propagation of cracks. Conventional continuum modeling of HMA lacks the ability to explicitly account for the effect of aggregate microstructure distribution features. This report presents the development of elastic and visco-plastic models that account for important aspects of the aggregate and microstructure distribution in modeling the macroscopic behavior of HMA. The objective of Project 0-1707 is to develop tools by which engineers can judge the impact of the aggregate on the performance of HMA based on simple and repeatable tests. Of greatest concern in Project 0-1707 is the ability of the HMA to resist permanent deformation or to rut, which leads to safety concerns, especially under wet surface conditions. In this report, the research team develops an approach is developed to introduce a length scale to the elasticity constitutive relationship in order to capture the influence of aggregate particle sizes on HMA response. A finite element (FE) analysis is used to analyze the microstructure response and predict the macroscopic properties of HMA. Each point in the microstructure is assigned effective local properties that are calculated using an analytical micromechanical model that captures the influence of the number of particles on the microscopic response of the HMA. The moving window technique and autocorrelation function are used to determine the microstructure characteristic length scales that are used in strain gradient elasticity. A number of asphalt mixes with different aggregate types and size distributions are analyzed . An elasto-visco-plastic continuum model is developed to predict HMA response and performance. The model incorporates a Drucker-Prager yield surface that is modified to capture the influence of stress path direction on the material response. Parameters that reflect the directional distribution of aggregates and damage density in the microstructure are included in the model. The elasto-visco-plastic model is converted into a numerical formulation and is implemented in FE analysis using a user-defined material subroutine (UMAT). A fully implicit algorithm in time-step control is used to enhance the efficiency of the FE analysis. The FE model used in this project simulates experimental data and pavement section.
Book Synopsis Unbound Granular Materials by : A. Gomes Correia
Download or read book Unbound Granular Materials written by A. Gomes Correia and published by . This book was released on 1999 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Unbound Aggregates in Roads by : R.H. Jones
Download or read book Unbound Aggregates in Roads written by R.H. Jones and published by Butterworth-Heinemann. This book was released on 2016-04-20 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unbound Aggregates in Roads contains the proceedings of the International Symposium on Unbound Aggregates in Roads (UNBAR3) held at the University of Nottingham, England, on April 11-13, 1989. The papers focus on unbound aggregates used in road construction and cover topics ranging from drainage and permeability to placement and compaction of unbound aggregates, design philosophy, specification, and compliance. This book consists of 49 chapters divided into eight sections and opens with an overview of the functions of unbound aggregates in roads, followed by a discussion on the mechanical properties of different aggregates and theoretical aspects of granular materials. The following chapters focus on granular drainage layers in pavement foundations; residual stresses caused by compaction in granular materials; and alternative materials for road construction such as steel slags and natural and waste materials. The use of unbound road aggregates in various countries such as Italy, France, Germany, and Portugal is also considered. This monograph will be a useful resource for designers, aggregate producers, contractors, specification writers, and materials engineers.
Book Synopsis Development of a Mechanistic Model for Geogrid Reinforced Flexible Pavements by : Jayhyun Kwon
Download or read book Development of a Mechanistic Model for Geogrid Reinforced Flexible Pavements written by Jayhyun Kwon and published by . This book was released on 2007 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the development of a mechanistic response model for the analysis of geogrid base reinforced flexible pavements and to investigate the response benefit of geogrid-reinforcement. This is an axisymmetric finite element structural model that considers the nonlinear, stress dependent pavement foundation geomaterials, i.e., unbound base aggregates and fine grained subgrade soils, anisotropic behavior of the granular base materials, as well as the compaction and preloading induced residual stresses in the granular base. The mechanistic model was used to investigate geogrid reinforcement mechanisms by considering locked-in horizontal residual stresses formed around the geogrid location for a proper modeling of the stiffening effect shown by the geogrid. These residual stresses are taken as initial conditions in pavement response analysis. To validate the response model, full-scale flexible pavement test sections, geogrid reinforced and unreinforced, were constructed at the University of Illinois Advanced Transportation Research and Engineering Laboratory (ATREL). Results from full-scale tests showed reduced critical pavement responses due to the inclusion of geogrid reinforcement. Higher percent reductions in lateral deflections in the aggregate base were realized especially in the direction of traffic. The anisotropic characterization of the granular base was needed to better capture the measured responses from the full-scale test sections. Field forensic and pavement trench studies were used to further calibrate the mechanistic response model. Typical increased horizontal residual stresses at the level of approximately 41 kPa was also needed 100 mm around the geogrid to better match measured pavement responses of the reinforced sections. As a result of the calibration efforts, the predicted responses at different locations in the test sections compared in general well with the field measured responses under different load levels.
Book Synopsis Permanent Deformation Behavior of Unbound Granular Materials and Rutting Model Development by :
Download or read book Permanent Deformation Behavior of Unbound Granular Materials and Rutting Model Development written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Minnesota Department of Transportation Research Services ... Annual Report by :
Download or read book Minnesota Department of Transportation Research Services ... Annual Report written by and published by . This book was released on 2009 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication provides a guide to the Minnesota Department of Transportation's current research activities.
Book Synopsis Constitutive Modelling of Granular Materials by : Dimitrios Kolymbas
Download or read book Constitutive Modelling of Granular Materials written by Dimitrios Kolymbas and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: In view of its extreme complexity the mathematical description of the mechanical behaviour of granular materials is an extremely difficult task. Today many different models compete with each other. However, the complexity of the models hinders their comparison, and the potential users are confused and, often, disencouraged. This book is expected to serve as a milestone in the present situation, to evaluate the present methodes, to clear up the situation, to focus and encourage for further research activities.
