Study of Dynamic Backcalculation Program with Genetic Algorithms for FWD on Pavements (original) (raw)
Related papers
KSCE Journal of Civil Engineering, 2010
The backcalculation program, GAPAVE, which uses the Genetic Algorithm (GA) and Finite Element Method (FEM), is developed to predict the layer moduli from Falling Weight Deflectometer (FWD) deflections. The use of the FEM in the forward calculation that incorporates the GA improves the accuracy in backcalculating the pavement layer moduli. The optimum GA parameters are selected from sensitivity analysis for six different pavement structures. It is found that the use of optimal GA parameters suggested from this study can improve the prediction quality in backcalculating the pavement layer moduli. FWD deflection data and resilient modulus test data obtained from the Long-Term Pavement Performance (LTPP) database are used to evaluate the performance of the GAPAVE program. Backcalculated layer moduli for the asphalt concrete and foundation layers are compared against the resilient moduli obtained from laboratory testing. The validation results indicate that GAPAVE with the optimal GA set of parameters can effectively estimate the actual stiffness characteristics of the pavement materials.
Information
In this paper, we propose a new method of optimization based on genetic algorithms using the MATLAB toolbox “Global Optimization”. The algorithm finds layers moduli of a flexible pavement through the measurement of pavement surface deflections under assigned load conditions. First, the algorithm for the forward calculation is validated, then the algorithm for the back-calculation is proposed, and the results are compared, in the case of airport pavements, with other software using different back-calculation techniques. The goodness of the procedure and the way of managing the algorithm operator is demonstrated by means of positive feedback obtained from the comparison of the results of ELMOD and BackGenetic3D. Moreover, the findings of the analysis prove that, in such an optimization procedure by GA, the best solution is always reached with a low number of generations, generally less than 10, allowing a reduction in the time of calculation and choosing a population big enough to sel...
2017
This report documents a study conducted to review the status of falling weight deflectometer (FWD) equipment, data collection, analysis, and interpretation, including dynamic backcalculation, and to develop enhanced analysis procedures and recommendations for the effective use of FWD technology as it relates to the flexible pavement models and procedures incorporated within the Mechanistic-Empirical Pavement Design Guide developed by the National Cooperative Highway Research Program and subsequently adopted by the American Association of State Highway and Transportation Officials. In this context, dynamic backcalculation refers to the modeling of the dynamic or impact nature of the FWD loading and resulting pavement response of in-service flexible pavements for pavement structural analysis and rehabilitation design. The research effort resulted in development analysis methodologies, software tools implementing those analysis methodologies and a potential list of recommendations for FWD equipment enhancements, all of which are detailed in this report. This report is intended for use by pavement engineers involved in structural evaluation and rehabilitation design of flexible pavements and researchers involved in development of new procedures for the modeling and analysis of in-service flexible pavements.
Transportation Research Record, 2003
A direct and simple method (YONAPAVE) for evaluating the structural needs of flexible pavements is presented. It is based on the interpretation of measured FWD deflection basins using mechanistic and practical approaches. YONAPAVE estimates the effective Structural Number (SN) and the equivalent subgrade modulus independently of the pavement or layer thicknesses. Thus, there is no need to perform boreholes which are expensive, time consuming and disruptive to traffic. Knowledge of the effective SN and the subgrade modulus, together with an estimate of the traffic demand, allows for the determination of the overlay required to accommodate future needs. YONAPAVE simple equations can be solved using a pocket calculator, making it suitable for rapid estimates in the field. The simplicity of the method, and its independency of major computer programs, makes YONAPAVE suitable for estimating the structural needs of a road network using FWD data collected on a routine or periodic basis along the network roads. With increasing experience and confidence, YONAPAVE can be used as the basis for NDT structural evaluation and overlay design at the project level.
Static and Dynamic Backcalculation Analyses of an Inverted Pavement Structure
Advanced Materials Research, 2013
A crucial part of any maintenance strategy is an intricate understanding of the material characteristics of the pavement, so that the current level of damage may be accurately assessed and an appropriate plan implemented. Advances in the precision to which these parameters can be determined, as well as improvements in how these results are interpreted under varying conditions of measurement and analysis, are essential in the effective execution of a maintenance strategy. Results from Falling Weight Deflectometer (FWD), which is a Non-Destructive Testing (NDT) device, can be used to predict elastic modulus of any layer by comparing measured deflection data to calculated values through an iterative process referred to as back-calculation. This paper presents a comparison between static and dynamic back-calculation procedures, specifically with regard to typical South African inverted pavements. The analysis indicates a dynamic analysis provides results of greater accuracy than a stati...
Nondestructive testing (NDT) is widely accepted technique used for the calculation of the mechanical properties of flexible pavements. Falling Weight Deflectometer (FWD) is the most preferred technique in all NDT methods. Basically, FWD measures time-domain deflections emerging by the applied impulse load, and the deflections are used for the calculation of mechanical pavement properties with a backcalculation tool. In the previous studies, traditional optimization algorithms were mostly treated in backcalculation tools; nevertheless, artificial intelligence (AI) techniques, such as neural networks, were utilized in the models developed recently. In this study, the applicability of AI techniques on backcaulating the mechanical properties of flexible pavements is considered as well as an example backcalculation problem is solved and discussed with this way of calculation. In this context, it is aimed for pavement engineers focusing on maintenance and rehabilitation strategies that to present a different viewpoint.
Deterioration Pattern of Flexible Pavement with the Help of Falling Weight Deflectometer
International Journal of Innovative Technology and Exploring Engineering (IJITEE, 2020
Maintenance and repair of the highway network system are major expenses in the state budget. For this reason, various concerned organizations are pointing out the need for developing an intelligent and efficient pavement performance model that can prioritize pavement maintenance and rehabilitation works. Such models can forecast the remaining pavement service life and pavement rehabilitation needs, and can help in the formulation of pavement maintenance and strengthening programmes which will reduce the road agency and road user costs. The flexible pavement performance or deterioration models involve the complex interaction between vehicles, environment, structure and surface of the pavement. Performance models relating to the pavement distress conditions like, cracking, ravelling, potholing, and roughness are analysed and developed by various researchers. Understanding the deterioration pattern of the flexible pavement is very important in order to take the decision for strengthening the pavement. The remaining life of the pavement depends on various factors such as Traffic, Environment and climatic conditions hence keeping in mind these factors. the thesis presents the pattern of the deterioration of remaining life of pavement. The thesis emphasis on determining the remaining life of pavement by conducting the FWD test. The FWD test is conducted on the same pavement for three time at regular interval to verify the remaining life of the flexible pavement.
REVIEW OF FALLING WEIGHT DEFLECTOMETER FOR ASSESSMENT OF FLEXIBLE PAVEMENT
ELK ASIA PACIFIC JOURNAL OF CIVIL ENGINEERING AND STRUCTURAL DEVELOPMENT , 2018
Fast development of road networks has become a trend in India and everywhere in the world. From the past couple of decades, it has been observed that numerous highways are in a phase of deteriorations. Identifying the reasons for deteriorations requires a pavement evaluation study. Many performances study have been made out by exploring flexible pavements, by the users of widely accepted falling weight deflectometer (FWD) as a non-destructive test (NDT) and considered it as a standard for structure assessment. The primary objective of this study is to a review of an FWD instrument and the also study of the empirically derived methods and a back calculation process for computing layer moduli and factors influencing it. The essential need of correction factors to get reliable layer moduli is an also discussed, in addition to the investigation of advancement of low-cost indigenous FWD models flexible pavements, by the users of widely accepted falling weight deflectometer (FWD) as a non-destructive test (NDT) and considered it as a standard for structure assessment. The primary objective of this study is to a review of an FWD instrument and the also study of the empirically derived methods and a back calculation process for computing layer moduli and factors influencing it. The essential need of correction factors to get reliable layer moduli is an also discussed, in addition to the investigation of advancement of low-cost indigenous FWD models
Modeling the Deflection Basin of Flexible Highway Pavements by Gene Expression Programming
Journal of Applied Sciences, 2005
In this study, Gene Expression Programming (GEP) is used in modeling the deflection basins measured on the surface of the flexible pavements. Backcalculation of the pavement layer moduli are well-accepted procedures for the evaluation of the structural capacity of pavements. The ultimate aim of the backcalculation process from Nondestructive Testing (NDT) results is to estimate the pavement material properties. Using backcalculation analysis, in situ material properties can be backcalculated from the measured field data through appropriate analysis techniques. In order to backcalculate reliable moduli, deflection basin must be realistically modeled. In this study, GEP was used to model the deflection basin characteristics. Experimental deflection data groups from NDT are used to show the capability of the GEP approach in modeling the deflection bowl. This approach can be easily and realistically performed to solve the problems which do not have a formulation or function about the solution.