Abstract

    Sediment resuspension is commonly assumed to be eroded from the seabed surface by an excess bottom shear stress and evolves in layers from the top down. Although considerable investigations have argued the importance of wave-induced seabed fluidization in affecting the sediment resuspension, few studies have been able to reliably evaluate its quantitative contribution till now. Attempt is made to preliminarily quantify the contribution of fluidization to resuspension using a series of large-scale wave flume experiments. The experimental results indicated that fluidization of the sandy silts of the Huanghe Delta account for 52.5% and 66.8% of the total resuspension under model scales of 4/20 and 6/20 (i.e., relative water depth: the ratio of wave height to water depth), respectively. Some previously reported results obtained using the same flume and sediments are also summarized for a contrastive analysis, through which not only the positive correlation is confirmed, but also a parametric equation for depicting the relationship between the contribution of fluidization and the model scale is established. Finally, the contribution of fluidization is attributed to two physical mechanisms: (1) an attenuation of the erosion resistance of fluidized sediments in surface layers due to the disappearing of original cohesion and the uplifting effect resulting from upward seepage flows, and (2) seepage pumping of fines from the interior to the surface of fluidized seabed.

Keywords

    erosion shear stress seepage flows pore pressure build up fine-grained particles Huanghe Delta

Foundation item: The National Natural Science Foundation of China under contract Nos 41272316 and 41372287; the Joint Fund of NSFC and Marine Science Research Centers of Shandong Province of China under contract No. U1606401; the Key Research and Development Program of Shandong Province of China under contract No. 2016ZDJS09A03.

Zhang Shaotong, Jia Yonggang, Wang Zhenhao, Wen Mingzheng, Lu Fang, Zhang Yaqi, Liu Xiaolei, Shan Hongxian*.Wave flume experiments on the contribution of seabed fluidization to sediment resuspension, Acta Oceanologica Sinica,2018,37(3): 80–87.     SCI-4