A idealized framework for the analysis of cohesive soils undergoing desiccation

Abstract

The authors wish to thank the discussers for their interest in the work on crack formation in clays during drying. The model presented by the authors holds for soils with a high clay content in which desiccation cracks form while the soil is still saturated. This was the case for the Saint-Alban clay for which cracks appeared for a suction of about 23 kPa, 18 hours after the soil surface was exposed to evaporation. Only the onset of cracking was modelled, and crack depth is approximated with linear elastic fracture mechanics in mode I, i.e., opening of the crack. Further crack propagation occurs with the ongoing evaporation leading eventually to the formation of secondary and even tertiary cracks if the soil is restrained in all directions. Furthermore, these cracks, depending on soil type, may be initiated in an unsaturated soil. Hence, we agree that the model must then also consider unsaturated soil mechanics. Owing to differential behaviour between a relatively dryer surface layer and soil at a higher moisture content with increasing depth, secondary crack propagation may also be controlled, in some cases, by shear failure at the crack tip. As stated by the discussers, the cracking problem is complex and the subject received little attention so far.