Discrete element modelling of desiccation cracking in thin clay layer under different basal boundary conditions

This study aims to investigate the effect of basal boundary conditions on the initiation and propagation of desiccation cracking along the vertical direction in thin clay layer using discrete element method (DEM). A two-dimensional discrete model was proposed considering shrinkage kinetics and property change during the drying process. Different basal boundary constraints were simulated by applying bond between the soil particles and the fixed base particles of difference sizes. The simulation results were compared with the laboratory experiments. The results showed that the model can reproduce the main trend of desiccation process. Larger base particles produced more cracks in the specimen. Both cracks initiated from the top surface and cracks initiated from the bottom soil-base interface were observed and discriminated in the simulation. The model revealed the development of bottom-initiated cracks and unpenetrated cracks beneath the surface that may be neglected in traditional cracking simulations. The study suggests that the different initiation position of cracks is associated with the change of force distribution inside the specimen. Moreover, the effects of different boundary properties (the geometrical roughness, the frictional coefficient and the bond strength), particle density change and evaporation gradient on model performance were investigated.

Automated summary

This study investigated the initiation and propagation of desiccation cracking in thin clay layers along the vertical direction under different basal boundary conditions using the discrete element method. The simulation results showed that larger base particles produced more cracks in the specimen, and both cracks initiated from the top surface and the bottom soil-base interface were observed. The study also revealed that the change in force distribution inside the specimen is associated with the different initiation positions of cracks.