Drained Monotonic Responses of Suffusional Cohesionless Soils

Mechanical consequences of suffusion on the noncohesive soils with various initial fine contents under different initial effective confining pressures are presented in this paper. By using the modified triaxial permeameter, seepage tests and successive drained monotonic compression tests are performed. It is found that soil-drained strength decreases after suffusion and a temporary drop in stiffness at the initial stage of shearing with respect to the axial strain ranging from 0 to 1% is observed. The tests suggest that suffusion might create a distinct packing of soil grains, which might result from possible accumulation of fine grains at the spots where the constriction size—representing the size of pore channels in a soil—is smaller than that of fines. Those surviving fines after suffusion may function as reinforcement or jamming at the subsequent compression, resulting in a larger initial stiffness of the suffusional soils.