Numerical Modeling Of Geosynthetic Reinforced Flexible Pavements
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Numerical Modeling Of Geosynthetic Reinforced Flexible Pavements
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Author : Steven W. Perkins
language : en
Publisher:
Release Date : 2001
Numerical Modeling Of Geosynthetic Reinforced Flexible Pavements written by Steven W. Perkins and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Geogrids categories.
Experimental studies conducted over the course of the past 20 years have demonstrated both general and specific benefits of using geosynthetics as reinforcement materials in flexible pavements. Existing design solutions are largely empirically based and appear to be unable to account for many of the variables that influence the benefit derived from the reinforcement. Advanced numerical modeling techniques present an opportunity for providing insight into the mechanics of these systems and can assist with the formulation of simplified numerical methods that incorporate essential features needed to predict the behavior of these systems. Previous experimental work involving the construction of geosynthetic reinforced test sections has shown several difficulties and uncertainties associated with the definition of reinforcement benefit for a single cycle of load application. Even though many reinforcement mechanisms are apparent and often times striking during the application of the first load cycle, the distinction between reinforced test sections is not nearly so clear as that which is seen when examining long term performance, where long term performance is defined in terms of permanent surface deformation after many load cycles have been applied. This indicates the need for an advanced numerical model that is capable of describing the repeated load behavior of reinforced pavements. In particular, models for the various pavement layers are needed to allow for a description of the accumulation of permanent strain under repeated loads. To meet these needs, a finite element model of unreinforced and geosynthetic reinforced pavements was created. The material model for the asphalt concrete layer consisted of an elastic perfectly plastic model where material property direction dependency could be added. This model allowed for the asphalt concrete layer to deform with the underlying base aggregate and subgrade layers as repeated pavement loads were applied. A bounding surface plasticity model was used for the base aggregate and subgrade layers. The model is well suited for the prediction of accumulated permanent strains under repeated loading and is most suitable for fine grained materials. A material model containing components of elasticity, plasticity, creep and direction dependency was formulated for the geosynthetic and calibrated against a series of in air tension tests. A Coulomb friction model was used to describe shear interaction between the base aggregate and the geosynthetic. The model is essentially an elastic-perfectly plastic model, allowing for specification of the shear interface stiffness and ultimate strength. This model was calibrated from a series of pull out tests. Finite element models were created to match the conditions in pavement test sections reported by Perkins (1999a). Membrane elements were used for the geosynthetic and a contact interface was used between the geosynthetic and the base course aggregate. Models of unreinforced and reinforced pavement sections were created and compared to test section resuts.
Evaluation Of Geosynthetic Reinforced Flexible Pavement Systems Using Two Pavement Test Facilities
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Author : Steven W. Perkins
language : en
Publisher:
Release Date : 2002
Evaluation Of Geosynthetic Reinforced Flexible Pavement Systems Using Two Pavement Test Facilities written by Steven W. Perkins and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Geosynthetics categories.
Montana State University has previously completed experimental test section, numerical modeling and design model development projects for the Montana Department of Transportation. Test section work has led to a fundamental understanding of mechanisms by which geosynthetics provide reinforcement when placed in the aggregate layer of flexible pavements. Finite element numerical models have relied upon this knowledge as their basis while design models derived from these numerical models have been calibrated against results from test sections. The test sections used for the development of these models were limited by the number of subgrade types, geosynthetic types and loading type employed. This project was initiated to provide additional test section data to better define the influence of traffic loading type and geosynthetic reinforcement type. The loading provided to the test sections forming the basis of the models described above consisted of a cyclic load applied to a stationary plate. In this project, four full scale test sections were constructed and loaded with a heavy vehicle simulator located at the U.S. Army Corps of Engineers facility in Hanover, NH. The four test sections used three geosynthetics identical to those used in previous test sections and pavement layer materials and thickness similar to previous sections. Additional test sections were constructed in the pavement test box used in previous studies to examine the influence of base aggregate type, base course thickness reduction levels and reinforcement type. A rounded pit run aggregate was used in test sections to evaluate the influence of geosynthetic aggregate shear interaction parameters on reinforcement benefit. The 1993 AASHTO Design Guide was used to backcalculate the base course thickness reduction from previous test section results where a traffic benefit ratio (extension of life) was known. Sections were built to this base course thickness reduction to see if equivalent life to an unreinforced section was obtained. Finally, six different geosynthetic products were used in test sections to evaluate the influence of reinforcement type on pavement performance.
Evaluation Of The Base Subgrade Soil Under Repeated Loading
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Author : Murad Yusuf Abu-Farsakh
language : en
Publisher:
Release Date : 2009
Evaluation Of The Base Subgrade Soil Under Repeated Loading written by Murad Yusuf Abu-Farsakh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Geogrids categories.
Mechanistic Empirical Modeling And Design Model Development Of Geosynthetic Reinforced Flexible Pavements
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Author : Steven W. Perkins
language : en
Publisher:
Release Date : 2001
Mechanistic Empirical Modeling And Design Model Development Of Geosynthetic Reinforced Flexible Pavements written by Steven W. Perkins and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Geogrids categories.
This report provides an appendix for the report with the reference: Perkins, S.W. (2001) Mechanistic Empirical Modeling and Design Model Development of Geosynthetic Reinforced Flexible Pavements: Final Report, Montana Department of Transportation, Helena, Montana, FHWA/MT 01 002/99160 1A, 156p. This report contains output from the software program DARWin for each design example provided in Appendix B of the above referenced report.
Finite Element Modeling Of Geosynthetic Reinforced Pavement Subgrades
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Author : Abdelaziz Ahmed Bohagr
language : en
Publisher:
Release Date : 2013
Finite Element Modeling Of Geosynthetic Reinforced Pavement Subgrades written by Abdelaziz Ahmed Bohagr and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Geosynthetic Reinforcement Of Flexible Pavements
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Author : Steven W. Perkins
language : en
Publisher:
Release Date : 1999
Geosynthetic Reinforcement Of Flexible Pavements written by Steven W. Perkins and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Roads categories.
Over the course of the last 17 years, approximately 12 different studies have shown the potential for the use of geosynthetic materials (geogrids and geotextiles) as a reinforcement inclusion in the base course aggregate layer of flexible pavements. The attraction of this application lies in the possibility of reducing the thickness of the base course layer such that a roadway of equal service life results or in extending the service life of the roadway. While several existing studies have provided data that aid in describing mechanisms of reinforcement, detailed information required to understand the mechanisms by which geosynthetics reinforce flexible pavements is lacking. In the absence of this information, it has historically been difficult to create mechanistic based models that adequately describe the process. As such, efforts to establish design solutions have been based largely on empirical data and considerations. Existing design solutions have not been met with open acceptance due to their inability to predict performance for conditions other than those established in the experiments for which the solution was based. This research was undertaken to provide experimental data that could be used to further establish the mechanisms of geosynthetic reinforcement that lead to enhanced pavement performance. Subsequent work will involve the use of these data in developing numerical models and design solutions for this application. Pavement test sections have been constructed in a laboratory based pavement test facility. The facility consists of a large concrete box in which field scale pavement layers can be constructed. Loading is provided through the application of a cyclic, 40 kN load applied to a stationary plate resting on the pavement surface. The test sections have been instrumented with an extensive series of stress and strain cells. Test section variables have included geosynthetic type (two biaxial geogrid products and one woven geotextile), subgrade type and strength, placement position of the geosynthetic in the base course layer and base course layer thickness. The results have shown that the inclusion of a geosynthetic provides a significant reinforcement effect. The geosynthetic is shown to have an influence on the amount of lateral spreading that occurs in both the bottom of the base course layer and in the top of the subgrade. Reinforcement is also seen to produce a more distributed vertical stress distribution on the top of the subgrade. As a result of these effects, reinforcement limits the vertical strain developed in the base and subgrade layers, leading to less surface deformation. Given that these mechanisms result from the development of shear interaction between the base and the geosynthetic, the combination of these effects is termed a mechanism of a shear resisting interface. These effects are seen to be most significant for a soft subgrade where substantial improvement in pavement performance has been observed. Geosynthetic type, strength, stiffness and placement position are also seen to influence observed improvement.
Numerical Methods In Geotechnical Engineering Ix Volume 2
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Author : António S. Cardoso
language : en
Publisher: CRC Press
Release Date : 2018-06-27
Numerical Methods In Geotechnical Engineering Ix Volume 2 written by António S. Cardoso and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-27 with Technology & Engineering categories.
Numerical Methods in Geotechnical Engineering IX contains 204 technical and scientific papers presented at the 9th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2018, Porto, Portugal, 25—27 June 2018). The papers cover a wide range of topics in the field of computational geotechnics, providing an overview of recent developments on scientific achievements, innovations and engineering applications related to or employing numerical methods. They deal with subjects from emerging research to engineering practice, and are grouped under the following themes: Constitutive modelling and numerical implementation Finite element, discrete element and other numerical methods. Coupling of diverse methods Reliability and probability analysis Large deformation – large strain analysis Artificial intelligence and neural networks Ground flow, thermal and coupled analysis Earthquake engineering, soil dynamics and soil-structure interactions Rock mechanics Application of numerical methods in the context of the Eurocodes Shallow and deep foundations Slopes and cuts Supported excavations and retaining walls Embankments and dams Tunnels and caverns (and pipelines) Ground improvement and reinforcement Offshore geotechnical engineering Propagation of vibrations Following the objectives of previous eight thematic conferences, (1986 Stuttgart, Germany; 1990 Santander, Spain; 1994 Manchester, United Kingdom; 1998 Udine, Italy; 2002 Paris, France; 2006 Graz, Austria; 2010 Trondheim, Norway; 2014 Delft, The Netherlands), Numerical Methods in Geotechnical Engineering IX updates the state-of-the-art regarding the application of numerical methods in geotechnics, both in a scientific perspective and in what concerns its application for solving practical boundary value problems. The book will be much of interest to engineers, academics and professionals involved or interested in Geotechnical Engineering. This is volume 2 of the NUMGE 2018 set.
Evaluation Of The Base Subgrade Soil Under Repeated Loading
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Author : Murad Yusuf Abu-Farsakh
language : en
Publisher:
Release Date : 2012
Evaluation Of The Base Subgrade Soil Under Repeated Loading written by Murad Yusuf Abu-Farsakh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Geogrids categories.
Mechanistic Empirical Modeling And Design Model Development Of Geosynthetic Reinforced Flexible Pavements
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Author :
language : en
Publisher:
Release Date : 2001
Mechanistic Empirical Modeling And Design Model Development Of Geosynthetic Reinforced Flexible Pavements written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Evaluating The Effectiveness Of A Hybrid Geosynthetic Reinforcement System To Mitigate Differential Heave On Flexible Pavement Due To Expansive Subgrades
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Author : Mir Md Tamim
language : en
Publisher:
Release Date : 2017
Evaluating The Effectiveness Of A Hybrid Geosynthetic Reinforcement System To Mitigate Differential Heave On Flexible Pavement Due To Expansive Subgrades written by Mir Md Tamim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Geosynthetics categories.
"Transportation industries encounter substantial challenges with respect to ride quality and serviceability when they deal with expansive soils underneath roadway structures. These soils exhibit swell-shrink behavior with moisture variations, which cause surficial heaving on the pavement structure and cost billions of dollars for the maintenance of pavements. For the past four decades, a particular stretch of US-95 (Oregon line to Elephant Butte) exhibited recurrent swelling distresses due to the underlying expansive soils. Despite remedial measures that exhibited satisfactory results for most of the sections, recurrent damage still continued in few sections. Further research indicated that the problematic soils were located at a depth below 1.82 m. Conventional chemical remediation methods typically performed at a depth no greater than 0.9 to 1.2 m. To be able to address the adverse effects of this swell-shrink behavior of soil at a deeper depth, hybrid geosynthetic systems were proposed. Hybrid geosynthetic systems were successfully used to mitigate expansive soil swelling in railroad applications. Hence, this research study explored this idea of using hybrid geosynthetic reinforcement systems (geocell-geogrid combination) to mitigate differential pavement heaving resulting from underlying expansive soils. To evaluate the use of hybrid geosynthetic systems in reducing differential heaving from expansive subgrades, a large-scale box test was developed to simulate a pavement section with a base course and expansive subgrade (asphalt overlay was ignored). The surficial heaving on the base course reinforced with geocell, geogrid and hybrid geosynthetic reinforced system (HGRS) were measured over time and compared with the unreinforced case. The large-scale box test results showed that the geosynthetic systems significantly reduced the maximum surficial heave along with the differential swelling on the pavement section. HGRS exhibited better performance than geocells and geogrids. Numerical analysis using the finite element approach was conducted to study the response of other soil types not tested in the box. The numerical model was first calibrated using using the box test results and the calibrated model was used to change soil properties for two other soil types with different swelling charecteristics. In the numerical model, swelling behavior of expansive soils was simulated using material models that incorporate volumetric swelling and suction as a function of moisture content. The modulus of the unreinforced base was determined using laboratory tests while the modulus that for the reinforced sections was calibrated using large scale test data. The calibration of control model was performed by controlling the moisture percolation through subgrade."--Boise State University ScholarWorks.