Application of image subtraction data to quantify suffusion

A method for the study of suffusion by means of visualisation experiments is presented. Suffusion is the removal of the finest grains from a widely graded soil due to seepage flow. The mobilisation and transport of grains is strongly coupled to the structure of the soil. Images are acquired at suitable spatial and temporal scales that allow for the coupled study of particle movement as well as the change in structure of the sample. The observations are made for a gap-graded plane strain sample behind a transparent window. Image subtraction is used for analysis of the results, i.e. the identification of areas of the sample where particle movement occurs, the evolution of the locations where particles are removed and their corresponding transportation paths and the evolution of particle motion over the height of the sample. The presented method therefore employs the same dataset to study particle motion and sample structure in space and time, thereby providing a means to address the coupling between them.