Coupling of hydraulic loading and surcharge pressure during suffusion in sandy gravels

Abstract

This study focuses on the coupling effect of the imposed hydraulic gradient and surcharge pressure on fine-particle loss and skeleton deformation during suffusion. A series of suffusion tests were conducted on an internally unstable sandy gravel under four different hydraulic gradients and three surcharge pressures using a large-scale high-pressure erosion apparatus. The total eroded mass, erosion rate and skeleton deformation were comparatively analysed, and the mesoscopic mechanism was discussed preliminarily. The results showed that the hydraulic gradient affected the erosion process not only in terms of the total eroded mass but also the developing pattern and duration of erosion. Surcharge pressure showed an inhibitory effect on fine-particle erosion, whereas a promoting effect on the skeleton deformation. For internally unstable soils, hydraulic gradient and surcharge pressure might have a considerable coupling effect on the fines eroded ratio and its induced strain.