On characterization of the imbrication of armored gravel surfaces

Imbrication of static armor surfaces is investigated based on laser-scanned DEMs collected from both flume experiments and the field. Two approaches are employed to study the imbrication including inclination index and aspect and slope (AS) method. The inclination index is found to be a sensitive and valid method for indicating the existence of imbrication. Application of this method, however, requires high-resolution surfaces. A positive relationship is obtained between the inclination index and effective grain size, which can be used to deduce the historical armoring shear stress. The AS method based on the statistics of local gradients describes the imbrication in a more straightforward way. However, this method is based on the statistics of orientations of grids rather than individual grains. An improved AS method is proposed in this study based on orientations of grains with the help of automated grain segmentation method. The improved AS method makes this method more reasonable and increases the applicable range.