Abstract
Soil–rock mixtures are widely
encountered in geotechnical engineering projects. The instability and
failure mechanism of grap-graded soil–rock mixtures under rainfall
conditions has always been the focus of geological disaster research. To
deeply explore the mechanism of seepage deformation of soil–rock
mixtures, an indoor physical permeability test that considers soil–rock
mixtures with different fine contents was conducted, and a
particle-scale numerical simulation test of the permeability evolution
was carried out using the coupling model of PFC3D and ABAQUS. The test
results showed that the spatial distribution of fine particle loss along
the height direction could be divided into three areas: top loss, middle
uniform, and bottom loss area. The “island” effect of coarse
particles, which is caused by excessive fine content and makes the fine
particles bear more load, was eliminated with the loss of fine
particles. In this preset working condition of coarse and fine particle
diameters, setting FC to 35% may be the best way to fill the voids
between the coarse particles. Particle migration leads to a change in
the load-bearing skeleton structure, thereby causing seepage
deformation. Therefore, the particle-scale numerical test method can
better reproduce the seepage deformation process of grap-graded
soil–rock mixtures.