盐度影响沉积物抗侵蚀性的环形水槽试验研究

Influence of salinity on sediment erosion-resistance:evidence from annular flume studies

黄河口海域盐度变化受入海径流量、海洋动力条件及气候等影响,时空变化显著。河口区盐度场的变化不仅会影响营养盐、污染物的运输,还会改变入海泥沙的沉降及固结特性,进一步影响沉积物的抗侵蚀性。为研究不同盐度环境对沉积物抗侵蚀性的影响,选用黄河三角洲沉积物进行室内循环水槽试验,模拟不同盐度条件下沉积物发生侵蚀再悬浮的过程。研究得出在本研究区盐度0~36‰范围内,黄河口细颗粒沉积物临界切应力值存在明显差异,变化范围为0.055 6~0.080 6 Pa。固结程度相同,沉积物临界切应力随盐度的增加呈对数增长特征,在盐度小于9‰的条件下,黄河口细颗粒沉积物抗侵蚀性受盐度环境变化的影响尤为明显;固结程度不同,随着固结时间的推移,盐度环境的增加对沉积物临界切应力的促进作用减小。

The temporal and spatial change of salinity field in the Yellow River estuary is affected by runoff,ocean dynamics and climate.It influences not only the transportation of nutrients and pollutants,but also the deposition and consolidation of sediments,and so that the erosionresistance of the sediments.In order to study the effect of salinity on the erosion-resistance of sediments,the sediments from the Yellow River estuary were used to carry out in-door annular flume experiments to simulate the process of sediment erosion and resuspension under different salinity conditions.The results show that the critical shear stress of fine sediments in the Yellow River estuary varies significantly in the salinity range of 0~36‰,and may be up to 0.0556~0.0806 Pa.Under same consolidation degree,the critical shear stress is logarithmically proportional to the increase in salinity,especially the salinity is less than 9‰.Under different consolidation degree,however,the effect of salinity on the critical shear stress of sediments decreases with the consolidation time.