Prediction of swelling pressure of expansive soil using an improved molecular dynamics approach combining diffuse double layer theory

Abstract

Swelling pressure of expansive soil is a fundamental parameter in the prediction of expansive soil behavior and also an essential quality indicator for geotechnical structure design. In this paper, we proposed a novel method by combining the diffuse double layer theory and molecular dynamics approach to predicting swelling pressure of expansive soil. The molecular structure was constructed based on the Na (Ca)-montmorillonite clay, which is the main mineral composition related to the swelling of expansive soil. The effects of electrical potential energy and van der Waals' energy were considered in this model. The proposed model was validated by comparing the predicted swelling pressure with the experiment results under different cation exchange capacities and dry density conditions. The capability of the model was discussed for different montmorillonite contents and interlayer cations. Two swelling pressure versus dry density graphs for montmorillonite with monovalent and divalent interlayer cations were developed for engineering application. The model calculated swelling pressures agreed well with the experimental results. This model provides a solid but cost-effective way to predict swelling pressure.