Predicting Subgrade Resilient Modulus from Other Soil Properties PDF Download

Author: Ronota Ann Woodbridge
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 222

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Author: Beresford O. A. Davies
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 182

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Subgrade soil plays a very important role in the construction of roadways. Before the use of asphalt in the construction of roadway, roads were being constructed based on experience. The introduction of paving asphalt in road construction has led to the development of engineering procedures and designs for the methods of construction. The resilient modulus of the underlying material supporting the pavement is now considered as a key material property in the AASHTO mechanistic-empirical design procedure. Attempts have been made by researchers to predict the Subgrade resilient modulus from laboratory/field experimental methods based on the soil properties. This research seeks to develop a model for predicting the subgrade resilient modulus due to environmental conditions by considering the seasonal variation of temperature and moisture content which affects the soil. The limitation of this research model is that it cannot be used universally since environmental conditions vary from place to place, however, it can be modified to suit other local environmental conditions. The detrimental effect of low resilient modulus of subgrade soil is observed in the damaged analysis.

Author:
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Category :
Languages : en
Pages : 64

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Subgrade soil characterization in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical specimens. Because the test is complex and time-consuming, in-situ tests would be desirable if reliable correlation equations could be established. Alternately, MR can be obtained from correlation equations involving stress state and soil physical properties. Several empirical equations have been suggested to estimate the resilient modulus. The main focus of this study is to substantiate the predictability of the existing equations and evaluate the feasibility of using one or more of those equations in predicting resilient modulus of Mississippi soils. This study also documents different soil index properties that influence resilient modulus. Correlation equations developed by the Long Term Pavement Performance (LTPP), Minnesota Road Research Project, Georgia DOT, Carmichael and Stuart, Drumm et al., Wyoming DOT, and Mississippi DOT are studied/analyzed in detail. Eight road (subgrade) sections from different districts were selected, and soils tested (TP 46 Protocol) for MR in the laboratory. Other routine laboratory tests were conducted to determine physical properties of the soil. Validity of the correlation equations are addressed by comparing measured MR to predicted MR. In addition, variations expected in the predicted MR due to inherent variability in soil properties is studied by the method of point estimates. The results suggest that LTPP equations are suited for purposes of predicting resilient modulus of Mississippi subgrade soils. For fine grain soils, even better predictions are realized with the Mississippi equation. A sensitivity study of those equations suggests that the top five soil index properties influencing MR include moisture content, degree of saturation, material passing #200 sieve, plasticity index and density.

Author: M. Shabbir Hossain
Publisher:
ISBN:
Category : Soils
Languages : en
Pages : 32

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In 2004, the Guide for the Mechanistic-Empirical Design of New & Rehabilitated Pavement Structures (MEPDG) was developed under NCHRP Project 1-37A to replace the currently used 1993 Guide for Design of Pavement Structures by the American Association of State Highway and Transportation Officials, which has an empirical approach. Implementation of the MEPDG requires the mechanistic characterization of pavement materials and the calibration of performance prediction models by the user agencies. The purpose of this study was (1) to determine the resilient modulus values for Virginia's subgrade soils for input into MEPDG design/analysis efforts, and (2) to investigate the possible correlation of the resilient modulus with other soil properties. Although the MEPDG provides default values and correlations for resilient modulus, they are based on a limited number of tests and may not be applicable for Virginia soils and aggregates. The possible correlation of the resilient modulus with other soil properties was investigated because such correlations could be used for smaller projects where costly and complex resilient modulus testing is not justified. More than 100 soil samples from all over Virginia representing every physiographic region were collected for resilient modulus, soil index properties, standard Proctor, and California Bearing Ratio testing. Resilient modulus values and regression coefficients (k-values) of constitutive models for resilient modulus for typical Virginia soils were successfully computed. There were no statistically significant correlations between the resilient modulus and all other test results, with the exception of those for the quick shear test, for which the correlation was very strong (R2 = 0.98). The study recommends that the Virginia Department of Transportation's Materials Division (1) implement resilient modulus testing for characterizing subgrade soils in MEPDG Level 1 pavement design/analysis, and (2) use the quick shear test to predict the resilient modulus values of fine soils using the relationships developed in this study for MEPDG Level 2 design/analysis

Author: Louay N. Mohammad
Publisher:
ISBN:
Category : Geogauge
Languages : en
Pages : 9

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Field and laboratory testing programs were conducted to develop resilient modulus prediction models for application in the design and evaluation procedures of pavement structures. The field testing program included conducting several in-situ tests such as Geogauge, Light Falling Weight Deflectometer, and Dynamic Cone Penetrometer (DCP). The laboratory program consisted of performing repeated load triaxial resilient modulus tests, physical properties, and compaction tests on soil samples obtained from tested sections. A total of four subgrade soil types at different moisture-dry unit weight levels were considered. Comprehensive statistical analyses were conducted on the field and laboratory test results. Two sets of models were developed. The first set (direct model) directly relates the laboratory measured resilient modulus values with the results of each of the three in-situ devices, whereas the second set (soil property model) incorporates soil properties in addition to the results of each of the three in-situ devices. A good agreement was observed between the predicted and measured values of the resilient modulus. Furthermore, the results showed that the resilient modulus prediction was enhanced when the soil properties were included as variables within the models. Among the models developed, the DCP-soil property model had the best prediction of resilient modulus followed by the DCP-direct model. The effectiveness of the DCP models were further evaluated during a forensic analysis of pavement section failure in a highway within Louisiana.

Author: Xin-She Yang
Publisher: Newnes
ISBN: 0123982960
Category : Computers
Languages : en
Pages : 503

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Due to an ever-decreasing supply in raw materials and stringent constraints on conventional energy sources, demand for lightweight, efficient and low cost structures has become crucially important in modern engineering design. This requires engineers to search for optimal and robust design options to address design problems that are often large in scale and highly nonlinear, making finding solutions challenging. In the past two decades, metaheuristic algorithms have shown promising power, efficiency and versatility in solving these difficult optimization problems. This book examines the latest developments of metaheuristics and their applications in water, geotechnical and transport engineering offering practical case studies as examples to demonstrate real world applications. Topics cover a range of areas within engineering, including reviews of optimization algorithms, artificial intelligence, cuckoo search, genetic programming, neural networks, multivariate adaptive regression, swarm intelligence, genetic algorithms, ant colony optimization, evolutionary multiobjective optimization with diverse applications in engineering such as behavior of materials, geotechnical design, flood control, water distribution and signal networks. This book can serve as a supplementary text for design courses and computation in engineering as well as a reference for researchers and engineers in metaheursitics, optimization in civil engineering and computational intelligence. Provides detailed descriptions of all major metaheuristic algorithms with a focus on practical implementation Develops new hybrid and advanced methods suitable for civil engineering problems at all levels Appropriate for researchers and advanced students to help to develop their work

Author:
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 96

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Field and laboratory testing programs were conducted to develop models that predict the resilient modulus of subgrade soils from the test results of DCP, CIMCPT, FWD, Dynaflect, and soil properties. The field testing program included DCP, CIMCPT, FWD, and Dynaflect testing, whereas the laboratory program included repeated load triaxial resilient modulus tests and physical properties and compaction tests. Nine overlay rehabilitation pavement projects in Louisiana were selected. A total of four soil types (A-4, A-6, A-7-5, and A-7-6) were considered at different moisture-dry unit weight levels. The results of the laboratory and field testing programs were analyzed and critically evaluated. A comprehensive statistical analysis was conducted on the collected data. The results showed a good agreement between the predicted and measured resilient modulus from the various field test methods considered. The DCP and CIMCPT models were enhanced when the soil moisture content and dry unit weight were incorporated. The results also showed that, among all back calculated FWD moduli, those back calculated using ELMOD 5.1.69 software had the best correlation with the measured Mr. Finally, the Mr values estimated using the approach currently adopted by the LADOTD were found to correlate poorly with the measured Mr values.

Author: Md Jibon
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 82

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"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: Anand J. Puppala
Publisher: Transportation Research Board
ISBN: 0309098114
Category : Technology & Engineering
Languages : en
Pages : 139

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At head of title: National Cooperative Highway Research Program.

Author: K. P. George
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 64

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