Mechanical consequences of internal soil erosion

Abstract

Internal erosion sometimes occurs in dams and slopes. Under seepage, fine particles in soil may migrate through the pores formed by the coarse matrix. The mechanical properties of the soil may then change due to the loss of fine particles. Extensive laboratory tests are conducted in this research to study the shear strength of a dense, internally unstable soil subjected to the loss of fine particles. The soil exhibited strain-softening behaviour prior to internal erosion. Once a significant amount of fine particles was lost, the strain-softening behaviour of the soil would turn into strain hardening. The peak shear strength of the soil decreased slightly, but the shear strength at the critical state increased slightly in response to the loss of fine particles. The peak friction angle decreased by 1.1–5.9° after a loss of 2.5–6.8% of fine particles. Finally, based on the findings of the study, a probable mechanism of the formation of sinkholes and cavities in slopes and slope failures associated with inter...