DEVELOPMENT OF METHODOLOGY FOR UTILITY DETECTION AND PAVEMENT LAYERS USING GPR

Abstract

There is always a need to maintain and rehabilitate the transportation infrastructure periodically. Therefore to reduce the cost of maintenance and rehabilitation, engineers have to optimize the procedure of rehabilitation which is achieved by accurate monitoring of pavement thickness and acknowledging any subsurface defect, anomalies or utilities present. Currently for these cases majority of the engineers still opt for destructive testing due to unavailability of reliable technique for analysis of data collected through non-destructive approach. GPR can be an effective non-destructive testing approach but is restricted by the fact that it requires skill professional for its data interpretation and majority of times it is done manually without assistance of computer. Therefore results obtained by manual or visual interpretation of GPR are often subjected to operator skills and sometimes may lead to erroneous interpretations. Without any data interpretation software interpretation of GPR data is highly time consuming. This research work attempts to overcome the drawbacks of non-destructive subsurface analysis using GPR. A methodology is developed for estimation of pavement layer (thick and thin) thickness, its health monitoring and identification of type of buried utility and anomalies present in it using near to accurate numerical modelling of the transmitted wave l'roni ground coupled GPR systems and application of match filter and Fourier transform. Various image and signal processing techniques has also been employed for detection of pavement layer interface and type of buried utility. The developed methodology is validated using data collected on experimental setups and pits. The layer thickness estimation error achieved through the methodology developed is 10 percent. While the percentage accuracy of determination of type of buried utility is more than 80 percent. More accuracy could be achieved if air coupled GPR system could be used for accurate determination of dielectric constant of medium.