黄河入海泥沙沉积固结过程抗侵蚀性变化研究

Study of erodibility change of Yellow River sediment into sea in process of consolidation

河口入海泥沙沉积固结过程中抗侵蚀性的变化直接决定着沉积物的再悬浮和二次迁移,对河口岸滩的稳定具有重要决定作用。在现代黄河三角洲潮滩模拟入海泥沙快速沉积,现场测试不同固结时间沉积物的抗侵蚀性和物理力学指标的变化。研究发现,黄河入海泥沙沉积物的抗侵蚀性随固结时间增长迅速提高,当沉积固结时间达8h时,其临界侵蚀切应力就超过了原状潮滩表层沉积物;新沉积泥沙的临界侵蚀切应力与其重度、贯入阻力、剪切强度呈良好的正相关关系,与含水率呈良好的负相关关系。黄河入海泥沙临界侵蚀流速的试验值随固结时间的增长速率要高于各泥沙起动公式计算值的增长速率,前者是后者的1.5～4.1倍。

The erodibility change of estuarine sediment in the process of consolidation directly determines the resuspension and secondary migration of sediment, which plays an important decisive role in estuarine and coastal stability. The rapid deposition of Yellow River sediment into the sea was simulated on the tidal flat of the modem Yellow River delta, and the erodibility and physico-mechanical properties of the sediment at different consolidation times were measured in situ. The results show that the anti-erodibility of the Yellow River sediment into the sea rapidly increases with consolidation time; and the critical erosion shear stress has already exceeded the value of the undisturbed tidal flat surficial sediment when the consolidation time extends as long as 8 hours. The critical erosion shear stress of the newly deposited sediment has a good positive correlation with bulk density, penetration resistance and shear strength, a good negative correlation with water content. The rise rate of measured critical erosion velocity of the Yellow River sediment into the sea with consolidation time is higher than the rise rate of calculated value using different formulas;and the former is 1.5-4.1 times as high as the latter.