SHRINKAGE CRACKS AND SUBSEQUENT GEOMETRIES

Shrinkage cracks are attributed to volumetric changes in saturated material. Mudcracks are most common, forming at the sediment-air interface by desiccation (drying). Syneresis cracks form similar geometric patterns, but form subaqueously, still by volumetric alteration. Although both processes may exhibit similar crack geometries, mudcracks are the easiest structures to model. Crack morphology relies on multiple factors: sediment composition, thickness, and surface configuration (discontinuities). Natural mud crack nucleation occurs from the bottom up due to the heterogeneity of the natural sediment. Heterogeneity is key in crack morphology due to a gradient in sediment grain-size. When the more saturated clays and fine-grained sediments exceed their tensile strength from desiccation, a crack forms. It is known that previously existing flaws or discontinuities in sediment surfaces aid in crack morphology. The purpose of this research is to investigate if these flaws orientate cracks based on four factors: (1) size of the introduced anisotropy (2) density (number of discontinuities per area) (3) density distribution (random placement versus clustered placement) and (4) orientation of the anisotropy (angle of alignment). Time-lapse photography will capture the formation of the modeled cracks and be formatted into a video to show crack growth and propagation. Results should show a preferred, directional orientation dictated by the introduced anisotropies.