Mechanical behavior of gap-graded soil subjected to internal erosion: comparison of suffusion and concentrated erosion

Abstract

Internal erosion causes massive damage to the soil local and integral fabric with loss of fine particles. In order to further compare the mechanical consequence of different internal erosion scenarios, a series of dissolution tests were designed to simulate suffusion and concentrated erosion by using small amounts of salt particles. For both salt-free clean sand specimens and erodible salt-sand specimens, drained triaxial compression tests combined with bender element measurement were performed to evaluate the degradation of stiffness and strength after internal erosion. Experimental results showed that the shear wave velocity decreased during water saturation. The concentrated erosion resulted more reduction in the shear wave velocity compared to suffusion at same mass erosion fraction of 1%. In general, all the relevant mechanical parameters, e.g. shear wave velocity, peak shear strength and volumetric strain, showed more significant decreasing characteristics in case of concentrated erosion, which indicated that concentrated erosion at key local positions would lead to more critical damage to the soil fabric.