With the rapid development of major infrastructure and urban construction in the Loess Plateau region, the problem of loess subsidence has become an important geological engineering challenge that restricts engineering safety and sustainable development (Figure 1). The compaction method is widely used in loess foundation treatment engineering due to its economy, efficiency, and convenient construction. However, the mechanism by which compaction suppresses loess collapsibility from the perspectives of microstructure and seepage behavior still needs to be explored. In response to the above issues, Yang Hui, a postdoctoral fellow in our geological engineering research team, has developed an integrated research system of "macroscopic experiments microstructure characterization three-dimensional pore reconstruction seepage numerical simulation". Through indoor collapse tests, scanning electron microscopy (SEM), X-ray micro CT (XRCT), XRD/XRF composition analysis, and three-dimensional pore network seepage simulation, the evolution of loess structure and the mechanism of collapse suppression under compaction were systematically revealed. The relevant achievements were published in the internationally authoritative journal "Journal of Rock Mechanics and Geotechnical Engineering" (IF 10.2, ranking first among international journals in the field of engineering geology). Dr. Yang Hui is the first author of the paper, and Professor Xie Wanli is the corresponding author.

The study found that as the compaction degree increases, the loess collapsibility coefficient significantly decreases. When the compaction degree reaches 95%, the collapsibility is basically suppressed (Figure 2). The compaction effect promotes the contact and bonding between particles, significantly reduces the number of large pores, and gradually transforms the pore structure from vertically dominant channels to a uniform and dense structure.

Further research has shown that compaction effectively suppresses the collapsibility of loess by promoting multi-scale structural hydraulic reorganization processes such as particle contact strengthening, pore network densification, tortuous seepage paths, and reduced permeability, achieving the transition of loess from a metastable structure to a stable engineering medium (Figure 5). At the same time, studies have pointed out that under long-term immersion, groundwater level fluctuations, and long-term engineering service conditions, compacted loess may still pose potential risks of secondary collapsibility, which need to be continuously monitored in engineering practice.

Paper information and link: Hui Yang, Wanli Xie, Qiqi Liu, Xinyu Li, Yingying Liu, Multiscale structural–hydraulic mechanism of loess collapse suppression by compaction, Journal of Rock Mechanics and Geotechnical Engineering, 2026, ISSN 1674-7755, https://doi.org/10.1016/j.jrmge.2026.02.016.