First Author: LI Weichao
Corresponding Author: DENG Gang
Journal: Computers and Geotechnics

Abstract

Gap-graded soils are commonly found in thick overburden, landslide deposits, and rockfill materials, characterized by unique mechanical properties and high susceptibility to seepage failure. The coarse-fine particle interactions largely control the overall mechanical behavior of such soils; however, these interactions cannot be directly observed in laboratory tests, limiting in-depth understanding of the underlying mechanisms.

This paper first points out that the Imperial College (IC) method for calculating the stress-partition ratio essentially does not take porosity into account and therefore cannot faithfully represent particle-scale interactions or shear deformation. To overcome this, we propose and employ a stress-partition ratio calculation method based on Thiessen polygons. Using this scheme, we analyze stress redistribution between coarse and fine fractions in gap-graded soils during shearing, considering the influences of shear stress level, density, and fines content. Results show that the critical state shear strength of gap-graded soils increases with the increase of confining pressure but exhibits a decreasing trend when fine particle content is high.

This research deepens the understanding of the mechanical behavior of gap-graded soils, and highlights the importance of evaluating critical-state shear strength under different conditions for engineering safety.

Keywords: Stress partitioning; Seepage failure; Critical-state shear strength; Potential erosion; Stress transmission