Microscopic mechanism and analytical modeling of seepage-induced erosion in bimodal soils

This paper investigates the seepage-induced erosion by conducting a series of discrete element method simulations on the bimodal soils with gap ratio (G) range from 2 to 6 and fines content (F) range from 15% to 70%. The final erosion ratio (Erf, the ratio of the eroded mass at the end of the erosion to the initial total mass) was found to increase as fines content increases and to sharply increase once fines content reaches a critical value (Fcr). Fcr decreases as the gap ratio increases and increases as the confining pressure increases, which can be determined by a fitted Boltzmann equation. The seepage-induced suffusion occurred when F < Fcr and the coarse particles are almost unchanged, while heave occurred, and the fine and coarse particles migrate together when F ≥ Fcr. Erf increases as the gap ratio increases and suddenly increases when G > 4, which agrees well with Kezdi's criterion. Erf decreases as confining pressure increases in underfilled and filled soils, whereas Erf may increase with confining pressure in overfilled soil. Finally, an analytical model based on dimensional analysis is proposed to predict the final erosion ratio.