A Study of Geosynthetic Reinforced Flexible Pavement System PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download A Study of Geosynthetic Reinforced Flexible Pavement System PDF full book. Access full book title A Study of Geosynthetic Reinforced Flexible Pavement System by Ranjiv Gupta. Download full books in PDF and EPUB format.
Author: Ranjiv Gupta
Publisher:
ISBN:
Category :
Languages : en
Pages : 562
Get Book Here
Book Description
The use of geosynthetics as reinforcement for the base layer of flexible pavement systems has grown steadily over the past thirty years. In spite of the evidence that geosynthetic reinforcements can lead to improved pavement performance, the specific conditions or mechanisms that enable and govern the reinforcement are unclear, largely remaining unidentified and unmeasured. The appropriate selection of design parameters for geosynthetics is complicated by the difficulty in associating their relevant properties to the improved pavement performance. In addition, pavement structures deteriorate under the combined effects of traffic loading and environmental conditions, such as moisture changes. However, these factors have not been studied together in the evaluation of the overall performance of pavement systems. Consequently, this research focused on the assessment of the effect of geosynthetics on the pavement structural section's ability to support traffic loads and to resist environmental changes. Accordingly, the primary objectives of this research were: (i) to determine the governing mechanisms and relevant properties of geosynthetics that contribute to the enhanced performance of pavement systems; (ii) to develop appropriate analytical, laboratory and field methods that are capable of quantifying the above properties for geosynthetics; and (iii) to enable the prediction of pavement performance depending on the various types of geosynthetics used. To fulfill these three objectives, an evaluative, laboratory and field study was performed. The improved performance of pavements due to addition of geosynthetics was attributed to the ability of geosynthetics to laterally restrain the base course material, thereby providing a confinement effect to the pavement. A parameter to quantify the soil-geosynthetic interaction at low displacement magnitudes based on the solution of an analytical model for geosynthetics confined in pullout box was proposed. The pullout tests were then conducted on various geosynthetics to obtain the proposed parameter for various geosynthetics. The quantitative magnitude of the parameter value from the laboratory tests was compared with the qualitative performance observed in the field test sections. Overall, a good agreement was obtained between the laboratory and field results, thereby providing confidence in the ability of the proposed analytical model to predict the governing mechanism for geosynthetic reinforced pavements.
Author: Ranjiv Gupta
Publisher:
ISBN:
Category :
Languages : en
Pages : 562
Get Book Here
Book Description
The use of geosynthetics as reinforcement for the base layer of flexible pavement systems has grown steadily over the past thirty years. In spite of the evidence that geosynthetic reinforcements can lead to improved pavement performance, the specific conditions or mechanisms that enable and govern the reinforcement are unclear, largely remaining unidentified and unmeasured. The appropriate selection of design parameters for geosynthetics is complicated by the difficulty in associating their relevant properties to the improved pavement performance. In addition, pavement structures deteriorate under the combined effects of traffic loading and environmental conditions, such as moisture changes. However, these factors have not been studied together in the evaluation of the overall performance of pavement systems. Consequently, this research focused on the assessment of the effect of geosynthetics on the pavement structural section's ability to support traffic loads and to resist environmental changes. Accordingly, the primary objectives of this research were: (i) to determine the governing mechanisms and relevant properties of geosynthetics that contribute to the enhanced performance of pavement systems; (ii) to develop appropriate analytical, laboratory and field methods that are capable of quantifying the above properties for geosynthetics; and (iii) to enable the prediction of pavement performance depending on the various types of geosynthetics used. To fulfill these three objectives, an evaluative, laboratory and field study was performed. The improved performance of pavements due to addition of geosynthetics was attributed to the ability of geosynthetics to laterally restrain the base course material, thereby providing a confinement effect to the pavement. A parameter to quantify the soil-geosynthetic interaction at low displacement magnitudes based on the solution of an analytical model for geosynthetics confined in pullout box was proposed. The pullout tests were then conducted on various geosynthetics to obtain the proposed parameter for various geosynthetics. The quantitative magnitude of the parameter value from the laboratory tests was compared with the qualitative performance observed in the field test sections. Overall, a good agreement was obtained between the laboratory and field results, thereby providing confidence in the ability of the proposed analytical model to predict the governing mechanism for geosynthetic reinforced pavements.
Author: Steven W. Perkins
Publisher:
ISBN:
Category : Geosynthetics
Languages : en
Pages : 120
Get Book Here
Book Description
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.
Author: Steven W. Perkins
Publisher:
ISBN:
Category : Geogrids
Languages : en
Pages : 156
Get Book Here
Book Description
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.
Author: Richard D. Barksdale
Publisher: Transportation Research Board National Research
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 68
Get Book Here
Book Description
Author: Bruce Anthony Lacina
Publisher:
ISBN:
Category :
Languages : en
Pages : 656
Get Book Here
Book Description
Author: Steven W. Perkins
Publisher:
ISBN:
Category : Geogrids
Languages : en
Pages : 97
Get Book Here
Book Description
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.
Author: Mir Md Tamim
Publisher:
ISBN:
Category : Geosynthetics
Languages : en
Pages : 127
Get Book Here
Book Description
"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.
Author:
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 247
Get Book Here
Book Description
Base reinforcement results from the addition of a geosynthetic at the bottom of or within a base course to increase the structural or load-carrying capacity of a pavement system. While there is clear evidence that geosynthetic reinforcements can lead to improved pavement performance, the identification and quantification of the parameters that contribute to such improvement has remained, at best, unclear. In addition, pavement structures deteriorate under the combined effects of traffic loading and environmental conditions such as moisture changes. The effect of moisture changes can be particularly detrimental in many locations of Texas, which are characterized by the presence of expansive clays. Consequently, this research focused on the assessment of the effect of geosynthetics on the pavement structural section and on its resistance to environmental changes. It is well documented that the use of geosynthetics for unbound base courses can lead to improved performance and reduced costs in pavement systems.
Author: Thomas Michael Vick
Publisher:
ISBN:
Category :
Languages : en
Pages : 288
Get Book Here
Book Description
In the summer of 2005, a geosynthetic-reinforced flexible pavement section was constructed in Northeast Arkansas by the University of Arkansas. The pavement section was constructed with seventeen individual test sections (each 15 m [50 ft] long). The first eight sections had an aggregate base coarse that was 25.4 cm (10 in) thick, the last eight sections had an aggregate base coarse that was 15.2 cm (6 in) thick and the aggregate in the center transition section tapered from 25.4 cm (10 in) to 15.2 cm (6 in) thick. There were a total of seven different geosynthetic configurations and a control section for each aggregate base thickness. The outside wheel path was instrumented with earth pressure cells, asphalt strain gages, geosynthetic foil strain gages, T-type thermocouples, and moisture content probes. A data acquisition system was used to acquire the responses to over 2,000 passes of a loaded, single axle dump truck. Over the course of testing, over 800 files of data were generated and processed. A file management and data manipulation process was developed by the author to organize, filter, process, analyze, evaluate, present, and archive the wealth of data into useable formats. The data manipulation procedure, a discussion of the time effort involved, and the difficulties encountered are discussed herein. Additionally, data analysis using Asphalt Institute transfer functions and Miner's hypothesis were employed to empirically evaluate the vehicle load responses acquired in Arkansas. The transfer functions were used to predict the damage induced in terms of alligator fatigue cracking and sub grade rutting. Finally, the results of the empirical rutting analysis were compared to actual field measurements provided to the author. Approximately half of the service life (in terms of rutting) was expended during the test for approximately 25% of the test sections, assuming a 13 mm (0.5 in) failure criterion. Unfortunately, the test site received roughly 70% of the anticipated rainfall. Therefore, the anticipated benefit of the geosynthetics (during the weakest conditions) was not observed, and the potential benefits associated with the geosynthetics were inconclusive. Further testing on this geosynthetic-reinforced flexible pavement test section in Arkansas will likely continue in the future.
Author: Steven W. Perkins
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 140
Get Book Here
Book Description
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.
