Back-calculation of Subgrade Resilient Modulus for Mechanistic-empirical Pavement Design in Wyoming PDF Download
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Author: Daniel K. Hellrung
Publisher:
ISBN: 9781321892161
Category : Pavements
Languages : en
Pages : 103
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Book Description
In an effort to build more cost effective and robust pavement structures, the Wyoming Department of Transportation (WYDOT) is in the transition of adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) instead of the 1993 AASHTO Pavement Design Guide. The University of Wyoming is currently conducting a comprehensive research study to facilitate the implementation of the MEPDG in the state. This thesis describes using a Falling Weight Deflectometer (FWD) as a non-destructive testing method for data collection and the development of a back-calculation testing protocol for estimating the resilient modulus of subgrade soils in Wyoming. During the summer of 2013, FWD testing was performed at 32 test sites throughout the state of Wyoming. Deflection measurements were collected and used to back-calculate the resilient modulus of the subgrade at each test site. The back-calculation protocol was developed by modifying the user guide of MODTAG, a back-calculation software, to achieve consistent and realistic back-calculated modulus results. Additionally, using these back-calculation results and laboratory measured modulus results for the same test site, two linear regression models were developed to correct the back-calculation results to laboratory equivalent values. The sum of square error (SSE) was used to compare the models and then select the most suitable one. The findings of this research will facilitate the MEPDG calibration which will help with the implementation of the MEPDG in the state of Wyoming.
Author: Daniel K. Hellrung
Publisher:
ISBN: 9781321892161
Category : Pavements
Languages : en
Pages : 103
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Book Description
In an effort to build more cost effective and robust pavement structures, the Wyoming Department of Transportation (WYDOT) is in the transition of adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) instead of the 1993 AASHTO Pavement Design Guide. The University of Wyoming is currently conducting a comprehensive research study to facilitate the implementation of the MEPDG in the state. This thesis describes using a Falling Weight Deflectometer (FWD) as a non-destructive testing method for data collection and the development of a back-calculation testing protocol for estimating the resilient modulus of subgrade soils in Wyoming. During the summer of 2013, FWD testing was performed at 32 test sites throughout the state of Wyoming. Deflection measurements were collected and used to back-calculate the resilient modulus of the subgrade at each test site. The back-calculation protocol was developed by modifying the user guide of MODTAG, a back-calculation software, to achieve consistent and realistic back-calculated modulus results. Additionally, using these back-calculation results and laboratory measured modulus results for the same test site, two linear regression models were developed to correct the back-calculation results to laboratory equivalent values. The sum of square error (SSE) was used to compare the models and then select the most suitable one. The findings of this research will facilitate the MEPDG calibration which will help with the implementation of the MEPDG in the state of Wyoming.
Author: Zachary R. Henrichs
Publisher:
ISBN: 9781321982947
Category : Pavements
Languages : en
Pages : 319
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Book Description
To improve the pavement design and construction in Wyoming, the Wyoming Department of Transportation (WYDOT) is adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG). Calibration of local subgrade materials are needed to implement the MEPDG. This thesis describes the measurement of resilient modulus (Mr) of subgrade materials and prepares a catalog of representative subgrade properties. As part of the comprehensive testing program, subgrade soil samples were collected from 12 locations throughout the state for standard laboratory tests and Mr test. A testing protocol for Mr was developed by modifying the AASHTO Designation: T-307 to incorporate WYDOT practices. Test results show that Mr changes with axial loads, confining pressures, soil types, and depths beneath the pavement. Regression models were developed using statistical methods and design charts were established for estimating Mr-values. The outcomes of this research will facilitate the full implementation of the MEPDG in the state of Wyoming.
Author: Anand J. Puppala
Publisher: Transportation Research Board
ISBN: 0309098114
Category : Technology & Engineering
Languages : en
Pages : 139
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Book Description
At head of title: National Cooperative Highway Research Program.
Author: Khaled Ksaibati
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 38
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Book Description
This report describes a study jointly conducted by the University of Wyoming and the Wyoming Department of Transportation to examine the factors influencing the determination of a subgrade resilient modulus value. The objectives of this study were to first, investigate the importance of several fundamental soil properties in determining a design subgrade resilient modulus value; and second, to define the actual relationship between back calculated and laboratory based resilient modulus values for typical cohesive subgrade soils in Wyoming. This study consisted of selecting nine test sites with cohesive subgrade soils in the state of Wyoming, conducting laboratory testing on subgrade cores obtained in 1992 and 1993, determining several fundamental soil properties on these cores, and using deflection data from these nine sites to determine resilient modulus values from three back calculation programs. The data analysis resulted in several important conclusions about factors that influence the selection of a design subgrade resilient modulus value.
Author: Harold L. Von Quintus
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 54
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Book Description
The Kansas Department of Transportation (DOT) uses the 1993 DARWin version of the 1986 AASHTO Guide to design rigid and flexible pavements. One of the inputs needed for the flexible pavement design procedure is the modulus of the subgrade soils, which has an effect on the total pavement thickness. Different procedures can be used to estimate the effective roadbed resilient modulus for flexible pavement design and effective modulus of subgrade reaction for rigid pavement design. As part of the study entitled Determination of the Appropriate Use of Pavement Surface History in the KDOT Life-Cycle Cost Analysis Process, an evaluation of the procedure that Kansas DOT uses to estimate the effective subgrade resilient modulus was completed. This report provides the results of that evaluation.
Author: Richard Ji
Publisher:
ISBN:
Category : Flexible pavement design
Languages : en
Pages : 11
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Book Description
This paper presents a comparison study of the experimental results from the falling weight deflectometer (FWD) test and laboratory resilient modulus test on granular subgrade materials and its application in flexible pavement design. Field and laboratory testing programs were conducted to develop a practical methodology for estimating resilient modulus (Mr) values of subgrade soils for use in the design of pavement structures. Soil characterization database was established for lab testing. A multiple regression model can be used to predict Mr value using several factors including soil properties, soil type and state of stresses for three popular American Association of State Highway and Transportation Officials (AASHTO) soil types (A-4, A-6, and A-7-6) in Indiana, and these prediction models developed were verified compared with laboratory Mr tests with high R2 value. In situ Mr seasonal variation based on abundant FWD test data in five field testing sites spread in Indiana was conducted in order to find the correlation between resilient modulus, temperature, and precipitation for the period from 2006 to 2012. The proposed method can accurately predict subgrade Mr of lab testing. However results from lab testing are significantly lower than recommended range by mechanistic-empirical pavement design guide (MEPDG) and backcalculation one using an adjust factor of 3. The design examples showed that the seasonal variation of temperature and precipitation as well as traffic can affect the design thickness by as much as 15 to 20 % in general. The findings of this study are expected to be helpful in the implementation of the pavement design in Indiana and elsewhere.
Author: Shabbir M. Hossain
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 34
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Book Description
To facilitate pavement design, the new proposed mechanistic-empirical pavement design guide recommends the resilient modulus to characterize subgrade soil and its use for calculating pavement responses attributable to traffic and environmental loading. Although resilient modulus values could be determined through laboratory testing of actual subgrade soil samples, such testing would require significant resources including a high level of technical capability to conduct the test and interpret results. For smaller or less critical projects, where costly and complex resilient modulus testing is not justified, correlation with the results of other simpler tests could be used. The Virginia Department of Transportation (VDOT) uses a simple correlation with the California bearing ratio (CBR) to estimate the resilient modulus in their current pavement design procedure in accordance with the 1993 AASHTO design guide. As this correlation with CBR is considered to be poor, a simpler unconfined compression (UC) test was explored for better estimation of the resilient modulus of fine-grained soils. Several models were developed in this study to estimate the resilient modulus of fine-grained soil from the results of UC tests. The simplest model considers only the UC strength to predict the resilient modulus with a fair correlation. The more detailed models with stronger correlations also consider the plasticity index, percentage of materials passing the No. 200 sieve, and modulus of the stress-strain curve from the UC test. These models are recommended for implementation by VDOT
Author: Michael J. Farrar
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 92
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Book Description
Author: Md Jibon
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 82
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Book Description
"The Mechanistic-Empirical (M-E) pavement design approach detailed in the Mechanistic-Empirical Pavement Design Guide (MEPDG), and subsequently implemented through AASHTOWare® Pavement ME Design relies extensively on detailed material properties that ultimately govern the analysis and performance prediction results. For unbound materials like soils and aggregates, Resilient Modulus (MR) is the most critical input parameter affecting layer response under vehicular and environmental loading. Representing a material’s ability to ‘recover’ after loading, resilient modulus is determined in the laboratory through repeated load triaxial testing. Although the original test protocol to measure the resilient modulus value of a soil or aggregate was developed back in the 1980’s, this test is still not widely used by state highway agencies because it is cumbersome, and requires significant investments towards equipment and personnel training. Accordingly, most agencies rely on correlation equations to predict the resilient modulus values for soils and aggregates from other easy-to-determine material properties. However, these correlation equations are mostly region specific, and therefore, do not produce adequate results across different geographic regions. This has led several state highway agencies to undertake local calibration efforts for improved prediction of material properties. Over the past decade, the Idaho Transportation Department (ITD) has invested significant resources to facilitate state-wide implementation of mechanistic-empirical pavement design practices. A research study was recently undertaken by ITD to develop a database of resilient modulus properties for different soils and aggregates commonly used in the state of Idaho for pavement applications. Another objective of the study was to assess the adequacy of different correlation equations currently available to predict soil and aggregate resilient modulus from easy-to-determine material (strength and index) properties. This Master’s thesis is based on tasks carried out under the scope of the above-mentioned project, and focuses on laboratory characterization and analysis of representative subgrade soil types collected from across Idaho. An extensive laboratory test matrix was developed involving commonly used mechanical and index tests, repeated load triaxial tests for resilient modulus determination, as well as tests to study the soil permanent deformation (plastic strain) behavior. Effect of moisture variation on soil strength, modulus, and permanent deformation properties was also studied by testing soil specimens at three different moisture contents. The test results were thoroughly analyzed to evaluate the feasibility of predicting resilient modulus from other material properties. Findings from this research effort have been documented in the form of two journal manuscripts. The first manuscript highlights the importance of using adequate subgrade resilient modulus values during pavement design. Eight different soil types were randomly selected from a total of sixteen soil types, and the corresponding laboratory test results were used to highlight the limitations of ITD’s current approach with assumed resilient modulus values. The second manuscript focuses on highlighting the importance of unbound material permanent deformation characterization during pavement design, and how small changes in moisture content can lead to significant differences in the rutting behavior of subgrade soils. First, a new permanent deformation testing protocol was developed to simulate typical stress states experienced by subgrade layers under vehicular loading. Subsequently, permanent deformation tests were carried out on subgrade soil types collected from two distinctly different regions in Idaho as far as annual precipitation is concerned. Tests were conducted at three different moisture contents to highlight how the rutting potential of the subgrade may change significantly based on site precipitation and drainage characteristics. Finally, recommendations were made regarding how state highway agencies can accurately represent resilient modulus properties of soils during pavement analysis and performance prediction using AASHTOWare® Pavement ME Design."--Boise State University ScholarWorks.
Author: David E. Newcomb
Publisher: Transportation Research Board
ISBN: 9780309068574
Category : Science
Languages : en
Pages : 84
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Book Description
This synthesis report will be of interest to pavement and geotechnical design and research engineers, geologists and engineering geologists, and related laboratory personnel. It describes the current practice for measuring in situ mechanical properties of pavement subgrade soils. The tests conducted to measure the mechanical properties of soil strength and stiffness are the primary topics, and these are discussed in the context of design procedures, factors affecting mechanical properties, and the variability of measurements. Information for the synthesis was collected by surveying U.S., Canadian, and selected European transportation agencies and by conducting a literature search. This TRB report provides information on existing and emerging technologies for static and dynamic, and destructive and nondestructive testing for measuring in situ mechanical properties of pavement subgrade soils. Correlations between in situ and laboratory tests are presented. The effects of existing layers on the measurement of subgrade properties, and soil spatial and seasonal variability are discussed. Most importantly, the use of soil properties in pavement design and evaluation are explained. New applications or improvements to existing test methods to support the use of mechanistic/stochastic-based pavement design procedures are also explained.
