Comparison of Different Programs for Analysing Falling Weight Deflectometer Data

Abstract

India has very large road network consisting of Expressways, National Highways, State Highways, District Roads and Rural Roads. In recent time, suitable maintenance and evaluation of road network is necessary requirement for any nation for its economic development. Evaluation of large road network is very difficult task for highway authorities. For the construction of expressways and highways huge amount of money is invested in India. There is need to evaluate these facilities regularly in terms of functional and structural performances to determine requirement for maintenance and rehabilitation measures. For structural evaluation, currently FWD is very popular because it simulates actual loading conditions of vehicles. As the use of the FWD is increasing the number of methods adopted for back-calculation of modulus values is also increasing. The use of these back-calculation methods without proper analysis may provide unreliable results. Therefore in order to decide the appropriate back-calculation methodology, there is a need for evaluation of different programs. The purpose of this study is to summarise the literature available on evaluation of different programs for analyzing FWD data throughout the world. This study discusses the process followed by various researchers for selecting various programs, back-calculation procedure used and outcomes of the program evaluations. The focus of thesis work is mainly on analysis of FWD data to compute moduli values of different layers obtained from different programs. In this study five back-calculation methods; namely, KUAB, EVERCALC, KGPBACK, Elmod (Deflection Basin Fit and Radius of curvature methods) are evaluated for consistency and reliability. Some Analytical methods AASTHO (1993), Garg and Thompson (1999), Roque (1998) were also used for determination of subgrade modulus values. These back-calculated modulus values were compared with laboratory calculated modulus values. Modulus values from different programs are compared using Pearson correlations and Statistical analysis.