中文摘要：

黄河入海沉积物自河口进入海洋后,在重力、水动力、生物改造等一系列外部作用下,经历着堆积、固结、液化、侵蚀再悬浮、海床变形滑动以及后期改造等一系列动态变化过程。研究团队近十几年来针对现代黄河三角洲沉积物的动态变化过程,开展了一系列的室内外物理模拟试验与水下三角洲现场原位长期观测等研究工作。在各动态变化过程的特征与机理方面,主要得到了以下认识：快速堆积后沉积物的固结速度很快,1—2天便可达到甚至超过原始海床强度,海床发育有显著的各项非均匀性,并发育有＂硬壳层＂。粉质土海床易于累积孔隙水压力,发生沉积物＂液化＂现象,一方面会改变海床表层沉积物的抗侵蚀性;另一方面,在海床内部垂向渗流的驱动下,海床内部部分细粒沉积物会被＂泵送＂输运到海床表面,进而进入上覆水体成为再悬浮沉积物,即部分再悬浮沉积物来源于海床内部。黄河三角洲坡度极缓,海底滑坡可以在近于水平的坡度条件下发生。波致海床液化引起的地层重构或海床渗流导致的内部土颗粒运移,可能会将相对均匀的海床改造为层化结构,这对河口地区沉积层理的解读具有新的启示。

英文摘要：

Yellow River derived sediments will experience a series of dynamic changing processes including deposition,consolidation,liquefaction,erosion to re-suspension,seabed deformation to submarine landslide and post-reformation of seabed under the action of gravity,hydrodynamics and bioturbation et al.Over the past decade,our research team has conducted a series of laboratory and field physical simulation experiments and in-situ observations on the subaqueous delta to investigate the feature and mechanism of each dynamic changing process,primarily found that：consolidation of rapidly-deposited sediments is pretty fast,of which the strength can reach or even exceed the native seabed in 1-2days,forming a significant depth profile of heterogeneity and ＂overlying crust layer＂.Silty seabed is easier to build up pore water pressures to induce seabed liquefaction,which will,on the one hand,change the erosion resistance of surface sediments;on the other hand,part of the fine-grained sediments will be pumped up to seabed surface and then become re-suspended sediments under the driving of seepage flows on seabed,i.e.part of re-suspended sediments originate from the interior of seabed.Slope of the modern Yellow River delta is extremely low,submarine landslide may occur over a nearly horizontal slope.It is possibly that stratum re-construction caused by wave-induced liquefaction or soil particle migration caused by seepage flows inside seabed could reform relatively homogeneous seabed into layered structure,which may provide a new insight into the formation mechanism of seabed stratification.