Collapsible loess presents serious geotechnical challenges in arid and semi-arid regions. This study combines oedometer collapse tests, component analyses, microstructure characterizations, and pore-scale permeability simulations to systematically explore the multiscale mechanisms by which compaction can suppress collapsibility. Oedometer tests verify that increasing compaction progressively reduces the compression strain and collapse coefficient, and at a compaction degree of 95%, the collapsibility is essentially suppressed. Scanning electron microscopy (SEM) and X-ray computed tomography (XRCT) results indicate that compaction increases particle contact, densifies pores, and reorients pore networks from being vertically dominant to being isotropically patterned. Energy-dispersive X-ray spectroscopy and compositional analyses indicate that carbonate redistribution contributes to contact modification. However, collapse is fundamentally governed by particle–pore structural evolution. Pore-network permeability simulations further demonstrate that compaction disrupts the continuous vertical seepage channels, increases the tortuosity, and reduces the permeability anisotropy. On this basis, a multiscale structural–hydraulic suppression mechanism is established, which links particle-contact reinforcement, pore-system stabilization, orientation adjustment, and seepage-path reconfiguration. This study presents a significant methodological advancement by constructing and quantitatively analyzing three-dimensional (3D) pore-structure models, combined with the application of the Stokes equation and Darcy’s law, thereby validating their effectiveness in capturing seepage behaviors within loess microstructures. These findings not only provide new microstructural insights into collapse suppression but also offer a transferable approach for evaluating the stability of metastable soils.
Yang et al. (2026) studied this question.