In this paper, the discrete element method (DEM) is used to study the microstructure of expansive soils. The results of the numerical calculations are in agreement with the stress-strain triaxial test curve that is obtained for a representative expansive soil. Biaxial compression tests are conducted for different confining pressures (50 kpa, 100 kpa, and 150 kpa). Attention is paid to the following aspects: deviatoric stress, boundary energy, friction energy, bond energy, strain energy, kinetic energy, and the contact force between grains when the test specimen is strained and to the effect of the different confining pressures on the internal crack expansion. The results of this research show that the cross-section of the specimen is destroyed along the middle part of the specimen itself. When the confining pressure is higher, the impulse is stronger, and this leads to more effective destruction.

Expansive soil; particle flow; parallel-bond; crack