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The objective of this study is to develop a mechanistic-empirical method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for asphalt pavements that uses multi-load level FWD deflections has been developed using these relationships. The verification study was conducted using field data.
The objective of this study is to describe a mechanistic-empirical approach to developing an analysis method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for pavement layers using multi-load level FWD deflections is presented in this study. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. However, large variations were observed in the relationships between the DBCI and desg values and the subgrade CBR values for aggregate base pavements. A FWD test with a load of 53 kN or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer are found to be better indicators than the deflection basin parameter. The procedures for performance prediction of fatigue cracking and rutting are developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using both single and multi-load level deflections show good agreement with measured rut depths over a wide range of rutting potential. However, the procedure using single load level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure usin.
Presents a complete coverage of all aspects of the theory and practice of pavement design including the latest concepts.
Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.
The objective of this study was to develop an approach for incorporating techniques to interpret and evaluate deflection data for network-level pavement management system (PMS) applications. The first part of this research focused on identifying and evaluating existing techniques, seeking out those that were simple, reliable, and easy to incorporate into current PMS practices, as well as those that produced consistent results. The second part of the research detailed the development of guidelines for the application of recommended techniques and procedures for determining optimum falling weight deflectometer (FWD) test spacing and data collection frequency. While there are many viable techniques available for evaluating the structural capacity of pavements that use FWD for project-level analysis, many of these techniques are time consuming and require an experienced analyst. As a result, using pavement deflection testing for network-level analysis has been limited to date. This guide provides information for the assessment of pavement structural performance for PMS applications. It reflects the general findings presented in the accompanying final report, Simplified Techniques for Evaluation and Interpretation of Pavement Deflections for Network-Level Analysis (FHWA-HRT-12-023).
Project monitored flexible pavement dynamic deflections, roughness, and distress over a six-year period. Results show present surface condition and serve as a basis for evaluating rehabilitation needs.
This book is a collection of selected research papers from the 14th conference of the Transportation Planning and Implementation Methodologies for Developing Countries (TPMDC). It covers the broad area of transportation planning and policy, pavement design and engineering, emerging technologies in transportation, traffic management, operations, and safety, and sustainable mobility in transportation. The book aims to provide deeper understanding of the transportation issues, solutions, and learnings from the implemented solutions. This book will be of best interest for academicians, researchers, policy makers, and practitioners.
This paper presents a methodology for testing, evaluation and determination of overlay thickness required for a given pavement section. The overlay design procedure presented makes use of some of the recent developments for analysis and design of asphaltic concrete overlays. The evaluation of in-service pavements includes the use of the deflection parameters developed by testing of the existing pavements with known geometry for determining the moduli of various pavement layers and the required overlay thickness. The method utilizes empirical values and VESYS structural subsystem as an integral approach complementary to each other. Six pavement sections across the State of North Carolina were selected for deflection testing. Deflection parameters were developed to characterize the deflection data from these pavement sections. In addition, VESYS structural system was used to develop nomographs for the interpretation of the measured deflection basin parameters. These nomographs were used to backcalculate the layer moduli form deflection parameters and known layer thicknesses using iterative solutions. The backcalculated layer moduli from these nomographs correspond to the climate conditions that happen to exist during the time of testing and must therefore be adjusted to other climatic conditions. A procedure for such an adjustment is also included in the design procedure. Many different methods have been developed for determining an overlay thickness. These methods can be categorized in three groups : component analysis, deflection based, and analytically based. A mechanistic procedure is described in this paper. This procedure is based on the data and findings of a previous research and has been used to evaluate in-service pavements in North Carolina using Falling Weight Deflectometer (FWD) deflection parameters. The procedure includes four major parts : (a) FWD deflection parameters and data collection, (b) back-calculation of layer moduli, (c) adjustment of layer moduli and (d) prediction of overlay thickness. For the covering abstract of this Conference see IRRD abstract number 853851.