Discrete-element simulation of drying effect on the volume and equivalent effective stress of kaolinite

The effect of the drying path on the porosity and equivalent effective stress of unsaturated kaolinite is investigated using the discrete-element method. An unsaturated model is developed to determine the distribution of water and calculate the capillary forces between the platy clay particles. Non-flexible and flexible clay particles are simulated and the results are compared with laboratory data to investigate the influence of particle flexibility on the accuracy of the results. Simulations with flexible particles were found to be more accurate than simulations with non-flexible particles. The effect of the pore water characteristics of cation valence, cation concentration and initial porosity on the drying process is also examined. A range of water contents for kaolinite was selected for pendular and partially pendular states. The results showed that, as the cation valence and concentration increased, porosity decreased and the equivalent effective stress increased. It was shown that a decrease in sample porosity increased the equivalent effective stress.