An experimental investigation of wave-induced sediment responses in a natural silty seabed: New insights into seabed stratification
An experimental investigation of wave-induced sediment responses in a natural silty seabed: New insights into seabed stratification
复制标题
天然粉质海底波浪诱发沉积物响应的实验研究：海底分层的新见解
DOI：
10.1111/sed.12312
复制
发表时间：
2017
期刊：
影响因子：
3.5
通讯作者：
Shan Hongxian
中科院分区：
文献类型：
--
作者：
Liu Xiaolei;Jia Yonggang;Zheng Jiewen;Wen Mingzheng;Shan Hongxian
波浪-海底相互作用的全球现象及其造成的次级分层过程是一个复杂的现象，人们对此知之甚少。为了更好地理解细粒和粗粒物质之间的差异以及新的沉积序列如何形成的机制，使用从黄河三角洲（中国）采集的天然粉质沉积物样品在不同波浪条件下进行了实验室水槽实验。详细的观察导致描述了在逐渐增加高度的波浪下沉积物的粒度组成和结构的变化，并认识到在孔隙压力增加和随后液化过程中形成的典型的二次形成的海底分层。分层海床的形成与波浪驱动的孔隙水流过沉积物密切相关，分层海床的特点是表层流体泥层、粗质和细质沉积物条带交替的次表层以及从上到下的内部液化层。局部流化和管涌的发生导致颗粒组成的逐渐变化，伴随着初始颗粒位错、大孔隙和微管道的发展，以及最终的管道形成。内部液化发生在超孔隙压力的临界值存在的情况下，在此期间，大多数细颗粒可被孔隙水流沿滑动面沿着冲刷，而粗沉积物颗粒沉降，从而形成更致密、更均匀的海床。这些元素相结合，以产生第一个模型的波浪诱导分层的开始和演变，在原来均匀的粉质海床。此外，该模型对未来研究的影响进行了探讨。
The widely recognized global phenomenon of wave–seabed interactions and the resulting secondary stratification processes are complex and poorly understood. To better understand the mechanisms by which the differentiation between fine‐grained and coarse‐grained materials occurs and how new sedimentary sequences form, laboratory flume experiments were performed under varying wave conditions using natural silty sediment samples collected from the Yellow River Delta (China). Detailed observations led to the description of variations in the grain‐size composition and texture of sediment under waves of progressively increasing height and the recognition of the typical, secondarily formed seabed stratification that forms during processes of increasing pore pressure and subsequent liquefaction. The development of a stratified seabed, which is characterized by a superficial fluid mud layer, a subsurface that alternates between coarse and fine sediment banding, and an internal liquefied layer from top to bottom, is closely related to wave‐driven pore‐water flow through the sediment. Localized fluidization and the onset of piping leads to progressive changes in the grain composition with initial particle dislocation, the development of macro‐voids and micro‐conduits and, finally, pipe formation. Internal liquefaction occurs in the presence of a critical value of excess pore pressure, during which most fine particles can be scoured by the pore‐water flow along the sliding surface while the coarse sediment grains settle, leading to a more compact, homogeneous seabed. These elements are combined to produce the first model of wave‐induced stratification initiation and evolution in an originally uniform silty seabed. In addition, the implications of this model for future studies are explored.