"Digital image analysis of dynamic compaction effects on sand"

By: Yahya Nazhat, School of Civil Engineering, University of Sydney

Abstract:

Applications of high speed digital photography coupled with digital image correlation analysis in dynamic laboratory 1 g model tests. The application involves dynamic compaction tests conducted at various impact velocities and masses under plane strain conditions. Preliminary results of the image analysis show that high speed photography provides valuable data on the mechanism of deformation, but the accuracy of determining soil displacements and strains are to be further investigated. The accuracy of a digital image-based measurement technique is a function of the errors associated with the processing algorithm, nature of image formation and the transformation process by which image-space coordinates “pixels” are converted into object-space coordinates. Results from high speed photography are also coupled with X-ray computerised tomography (Micro CT scan) to quantitatively assess the changes in soil density and the generated deformation patterns at micro-strain levels. The principles, details and accuracy of the procedure are described, as well as its suitability to properly represent the patterns of deformation and the effective depth of soil improvement.