Damage study of solid waste geopolymer stabilized soil under freeze-thaw cycles

To investigate the microscopic damage mechanism of soil property deterioration under freeze-thaw cycles, a discrete element method (DEM)-based approach using water particle expansion to simulate freeze-thaw damage in soil is proposed. The stress–strain curves obtained from uniaxial compression tests are used to calibrate the microscopic parameters of geopolymer-stabilised soil under different numbers of freeze-thaw cycles. Uniaxial compression simulations are then conducted on the freeze-thaw damaged stabilised soil model, revealing the evolution of microcracks, displacement fields, and force chain fields, as well as the fracture characteristics of freeze-thaw stabilised soil under loading. The results indicate that (1) the stress–strain curve obtained by discrete element simulation is in good agreement with the experimental compressive strength. (2) As the number of cycles increases, the damage evolution of the soil exhibits distinct stages: initial emergence of localised damage zones; microcrack propagation and coalescence with enhanced localisation of displacement fields; and a damage saturation stage in which the soil approaches a critical state. (3) The contact force chain evolves in a pattern of ‘disordered-concentrated-dispersed-reconcentrated’ with freeze-thaw damage, whereas the pore structure undergoes an adjustment process of ‘isolated-locally connected-interconnected – stabilised by fine particle filling’.