Particle transport characteristics and filtration of granitic residual soils from the Korean peninsula

Weathered granitic residual soils, which are found in much of the Korean peninsula, pose unique challenges in terms of internal stability and filtration. The particle transport and filtration behavior of two extreme soil types, named Shinnae-dong and Poi-dong, are investigated in this paper. The erodibilities of the two soils are evaluated using constant flow-rate experiments on both undisturbed samples and samples with cylindrical holes. A comparison of the results from these experiments revealed the extent of particle redeposition and self-filtration in the internal erosion process. In spite of the differences in the mineralogical properties and engineering characteristics of the two soils, the size of the eroded particles from the two soils fell within the same range of 1-100 μm. The two soils were coupled with filters, chosen according to the US Bureau of Reclamation's (USBR) filter criteria, to determine the efficiency of filters in minimizing erosion. It was found that the filters significantly minimized the erosion of the two base soils. However, the associated reductions in filter permeability are greater than one order of magnitude. Experiments using filters alone with particulate suspensions as the influents enabled the evaluation of a coefficient, λ, which could be used to characterize the particle retention capacities of the filters.