Experimental Investigation on Erosion Progression and Strength Reduction of Gap-Graded Cohesionless Soil Subjected to Suffusion

Suffusion is a typical mode of internal erosion that leads to the deterioration of earthen structures. A stress-controlled experimental apparatus has been developed, which is adopted to investigate the characteristics of the erosion process and strength reduction of gap-graded cohesionless soil subjected to suffusion. Experimental results reveal that the critical hydraulic gradient significantly relates to the relative content of fine and coarse particles. Besides, under the same stress condition, the suffusion process is divided into three typical stages, i.e., the steady seepage stage (S1), the suffusion initiation stage (S2), and the suffusion equilibrium stage (S3). The suffusion process and the responses of the soil strength are explored with a newly defined coefficient, i.e., erosion ratio (ER). The coefficient ER is defined as the percentage of the cumulative weight of the eroded fine particles to the initial fine particle content in the specimen. The experiment results reveal that when ER is smaller than 6