Suffusion of gravel–sand mixtures under cyclic hydraulic gradient with emphasis on tracking the migration of fine particles Available to Purchase

The migration of fine particles of gravel–sand mixtures subjected to suffusion plays a significant role in understanding the development of internal erosion-induced failure of hydraulic structures. This paper presents an experimental study on the progress of the suffusion of gravel–sand mixtures under three cyclic hydraulic gradient amplitudes (i.e. Δi = 0·25, 0·375, 0·5) and three average hydraulic gradients (i.e. i_mean = 0·75, 1·5, 2·25). Examination of the composition and origin of eroded particles is performed using particle staining and image recognition techniques. The results indicate that the higher amplitude of the cyclic hydraulic gradient leads to more pronounced particle loss channels, resulting in more loss of fine particles and more significant changes in hydraulic conductivity. The increased mean hydraulic gradient facilitates the development of new particle migration channels, leading to soil transition into the subsequent erosion stage. The loss of soil particles is primarily composed of fine particles ranging from 0·075 to 0·25 mm in size, occurring mainly during the initial stage of hydraulic gradient loading and at locations experiencing high hydraulic gradients. With increased cyclic gradient amplitude and the mean hydraulic gradient, suffusion gradually progresses from the top layer to the bottom layer of the soil. These findings can deepen the understanding of the characteristics and mechanisms of suffusion of gravel–sand mixtures.