Desiccation-induced curling of mud layers on the earth surface is a ubiquitous natural phenomenon, as a result of mud-atmosphere interaction. Field observations reveal that the curling behaviors of muds were closely related to the overlying layer thickness and the basal layer condition. In order to interpret field observations, laboratory experiments were conducted on ten remolded mud samples with varying overlying layer thicknesses and basal conditions. Experimental results are consistent with field observations and provide insights into the dynamic mud curling process. During drying, the mud curling is driven by the shrinkage strain gradient along the mud profile. For a thin overlying mud layer, the mud curling is unidirectional, either upward (∪) or downward (∩), depending on the basal condition. For a thick overlying layer, the mud begins with upward curling and then recovers. Increasing the layer thickness not only weakens the mud curling but also improves the curling recovery capacity. Furthermore, under a stratified structure, the overlying mud curling is significantly influenced by the interplay of the capillary and friction forces developed at the mud undersurface. Both factors are strongly associated with the basal particle size. The decreasing basal layer particle size smoothens the interface, probably causing the unidirectional downward curling of the overlying layer. However, a rougher basal layer may induce that the overlying mud curls initially at a higher water content and undergoes a more noticeable upward curling. Through field observations and experimental tests, this study is expected to advance the current understanding of various mud curling processes.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology