Experimental Study on Sediment Suspension over the Liquefied Sand-clay Seabed under Waves

Abstract

The characteristics of erosion and sediment suspension over the wave-induced liquefied mixed seabed are investigated experimentally in this study, as well as the mechanism underlying the phenomena. The mixed beds with various Clay Content (CC) ranging from 0 to 9.9 % were tested under a specific wave condition. The erosion depth of beds, Excess Pore water Pressure (EPP), and Suspended Sediment Concentration (SSC) are measured and analyzed at different liquefaction stages, and their relationships with CC are emphatically discussed. The results show that the erosion depth and SSC vary non-linearly with CC. The cohesive beds with 0.5 % and 1 % CC erode more significantly than the cohesionless sand bed. The erosion depth and SSC of mixed beds with >1 % CC, decrease with the increase of CC. The accumulated EPP significantly reduces the critical shear stress of the beds through the seepage force, while the cohesive force from the clay content increases it, leading to the complicated phenomena of mixed seabed under wave actions.