Characteristics of the Sediment Gravity Flow Triggered by Wave-Induced Liquefaction on a Sloping Silty Seabed: An Experimental Investigation

Abstract

The sloping silty sediments in estuarine deltas are frequently affected by extreme storms, and they are prone to liquefaction instability. The unstable liquefied sediments of the slopes can subsequently form a sediment gravity flow (SGF), which can seriously endanger offshore engineering facilities. To better understand the characteristics and mechanism of wave-induced liquefied sediment gravity flow (WILSGF), a flume experiment was conducted to reproduce the formation, movement, and deposition processes of the WILSGF and analyze their controlling factors using natural silty sediment samples collected from the Yellow River Delta in China. The results show that the mass of the WILSGF comes from the sediment in the liquefied layer, and the movement of the WILSGF in these experiments was significantly affected by the wave orbital velocity and the relative outflow position. At the initial stage of the formation of the WILSGF, the phase and amplitude of the WILSGF were the same as those of waves, and the maximum velocity of the WILSGF reached 2.39 cm/s. The velocity of the WILSGF decreased continuously with the downward evolution of the liquefaction interface. When the liquefaction depth reached its maximum value, there was no WILSGF. We also found that the median particle size of the WILSGF was greater than that of the original seabed due to wave-induced seabed coarsening and the intrusion of ambient water. This study has guiding significance for in-depth understanding and prediction of the geological hazards caused by WILSGF.

An experimental study on monitoring of marine sediment transport by using a 3D sediment trap

“…The mechanism of transport of marine sediments is influenced by a variety of factors in the oceanographic environment, including tides, intra-ocean waves, turbidity currents, sand wave migration, and this leads to continual changes in their location and state of storage (Lowe, 1982;Nelson et al, 1995;Peng et al, 2018;Reeder et al, 2011;Jia et al, 2019). This mechanism is also influenced by the physical and chemical properties of the sedimentary particles as well as the nature of the boundary layer of the seafloor (Yu et al, 2022). These factors cause the overall process of transport of marine sediment to become complex and variable (Li and Xu, 2013).…”

In‐Situ Observation of Storm‐Induced Wave‐Supported Fluid Mud Occurrence in the Subaqueous Yellow River Delta

“…WSFMs require a specific terrain slope to create the probability for WSFM gravitational flow (Flores et al., 2018; Hale & Ogston, 2015). Many attempts in field, laboratory, and modeling have sought to understand the WSFM dynamics and its controlling factors (Hale & Ogston, 2015; Hooshmand et al., 2015; Traykovski et al., 2007; Yu et al., 2022; Yue et al., 2019), for example, downslope gravitational velocities and high concentration conditions, but it is widely acknowledged that there is no comprehensively theoretical framework for analyzing sediment motions in WSFMs. WSFMs were observed to be widely distributed in continental shelves around the world, including examples of northern California/Eel River continental shelf (Ogston et al., 2000; Traykovski et al., 2000), Waipaoa River continental shelf (Hale et al., 2014; Hale & Ogston, 2015), shallow shelf in Gulf of Mexico (Kineke et al., 2006), and Atchafalaya subaqueous clinoform (Jaramillo et al., 2009; Sahin et al., 2012; Sheremet et al., 2011).…”