Micromechanics of collapse in loess

Soil collapse is amongst one of the most significant ground related hazards. A collapsible soil, in particular loess, typically has an open-structure and collapse occurs when as a consequence of the addition of water and/or load the particles rearrange to form a more dense fabric. Collapse leads to a suite of problems for buildings and infrastructures built on or in collapsing soil. Treatment to mitigate collapse often involves in densification. However, such approaches have been reported not always effective enough to combat the problem. This stems from a lack of understanding of soils’ geochemistry and structure, the result of which is an oversimplification of complex geotechnical and geological interactions. An important example of such limited knowledge is the increasing evidence of restoration of the collapsing structure upon wetting-drying cycles, which is widely ignored in the current compaction practice. This research aims to first identifying collapse micro-mechanisms in fine-grained soils, examining the contribution of a handful of soil constituents in collapsibility, and finally developing a practical tool for ground engineers to evaluate the efficiency of the current compaction practice for systematically classified fine-grained soils, and to take modified/novel earthwork approaches where the current practice fails to fully remove the collapse risk