Studies of crack dynamics in clay soil

We propose a small set of fundamental geometric measures which provide a quantitative description of crack patterns at the soil surface including their dynamics. These measures (Minkowski numbers) are combined with tools of mathematical morphology to obtain Minkowski functions. Additionally, we measured the distribution of angles within the crack network to characterize the form of aggregates. The methods are demonstrated for two experiments using different mixtures of sand (S) and bentonite (B). We found that the different crack patterns can be clearly distinguished both with respect to the dynamics of crack formation and with respect to the final crack pattern. In contrast, the frequency distribution of angles within the crack pattern was found to be invariant which is supposed to reflect the common physical processes of crack formation.