ABSTRACT
Digital image correlation, while common in other geotechnical investigations, has seen limited use in flexible pavement research. Due to the loading conditions, boundary effects, and physical limitations of bifurcating a pavement structure perpendicular to the tyre travel path, challenges not experienced in either pavement or image correlation research, need to be considered. Granular displacement in pavement research is generally obtained via surface deformation measurement. In-situ instrumentation and post-test trenching can also be used but with significant limitations. The Cambridge Airfield Pavement Tester (APT) was created to explore the possibilities of image correlation use in flexible pavement research. Multiple hi-resolution cameras took images of a pavement structure’s cross-section as a tyre moved across its surface through a Perspex window. By tracking discretized soil patches from one image to another sub-pavement deformation fields were measured in-situ.
Image correlation has been shown in other research to significantly increase measurement accuracy relative to previously utilised techniques. The results from an ongoing series of pavement experiments are presented. A study comparing results to linear elastic predictions reveals the method under-estimates deformation, likely due to the method’s inability to account for the myriad of parameters which influence granular material behaviour. The novelty of this application made opportunities to visualise concepts and quantify movement only predicted in pavement theory possible.
