大小潮作用对潮滩沉积物层理影响的数值模拟研究

潮滩垂向沉积韵律层的形成主要取决于周期性的潮汐条件，包括涨落潮、大小潮、季节性及更长时间尺度的潮汐特征，为探究大小潮周期对潮滩沉积物垂向层理形成机制的影响，应用一维潮流泥沙与底床分层数学模型，对周期性潮汐条件作用下潮滩垂向沉积韵律层形成机制进行了数值模拟研究。结果表明，大小潮的周期性是模型中沉积层理表现韵律性的主要原因之一，韵律层中单个层理结构对应于1个大小潮周期过程，层理结构由形成于小潮期间的泥质层及形成于大潮期间的砂质层组成，层理的厚度也呈旋回性变化，大潮时层理较厚而小潮时层理较薄。水体边界含沙量是影响潮汐层理结构的重要因子，边界含沙量中粉砂占比增大会使潮汐韵律层整体粗化且砂质层厚度增大，当边界含沙量整体显著增大时，潮滩上的垂向潮汐韵律层会更加完整且厚度明显增大。潮汐层理的形成与特征是多种因子共同作用的结果，后续需进一步探究包括波浪、风暴潮、潮滩生物等其他因子的作用。

The effects of spring-neap tide on sediment bedding on tidal flats: A numerical study

The formation of vertical sedimentary rhythmic layers of tidal flat mainly depends on periodic tidal conditions, including flood and ebb tide, spring and neap tide, seasonal and longer term scale tidal characteristics. In order to investigate the distribution and mechanism of sediment bedding on tidal flats, a one-dimensional numerical model was used to simulate the rhythmic layers of long-term tidal flat bedding layers under spring and neap tidal cycles. Results indicate that the periodicity of spring-neap tide is the main reason for the rhythmicity of sedimentary bedding. One couplet in the rhythm layer corresponds to the spring-neap tidal period, which is formed by the mud-dominated layer during the neap tide and the sand-dominated layer during the spring tide. The thicknesses of layers also show a cyclical change: bedding layers are thicker during the spring tide and thinner during the neap tide. The boundary sediment concentration is also an important factor affecting the structure of tidal couplets. An increasing boundary concentration of silt makes the tidal rhythm layer coarser and increases the overall thickness of the sand-dominated layer. When the boundary sediment concentration significantly increases, the vertical tidal rhythm layers on the tidal flat are more intact with an evident increase in layer thickness. The formation and characteristics of tidal bedding layers are the result of the joint action of many factors (e.g., waves, storms, biological factors and etc.), which await further research effort in the future.