Modelling cracking stages of saturated soils as they dry and shrink

Summary Cracks that form when clay soils shrink on drying eventually form a network that determines transport properties. I propose and validate a model for (i) analysing the initial cracking stages of shrinking saturated soils, (ii) estimating the minimum dimension of quasi‐brittle cracks capable of developing in such conditions, and (iii) determining relations between the minimum crack dimension and other characteristic dimensions of the soil structure. Shrinkage cracks in soils can be classified on the concept of the minimum quasi‐brittle crack capable of developing at shrinkage. I use the model of developing a shrinkage crack in a semi‐infinite brittle medium with constant relevant properties, desiccating in conditions of shock drying. The model is generalized to the cracking of a saturated clay soil with a limited maximum crack depth. The available data justify the use of constant elastic, strength, diffusivity, and shrinkage properties of clay soil. The critical point of crack development is the existence of the minimum crack capable of developing in the particular conditions. The dimension of the crack is related to the soil properties. The crack goes through stages of delay, jump, stable growth with approximately constant velocity, and then quick decline until it stops. I show that the minimum crack dimension is related to the mean dimension of soil particles, the thickness of an upper intensive‐cracking layer, and the mean spacing of primary cracks at the soil surface.