黄河流域黏性泥沙群体沉速计算分析

Examination of cohesive sediment settling velocity calculations in the Yellow River Basin

  • 摘要: 针对黄河流域由黏性矿物组成的黏性泥沙群体沉降特征展开研究。基于泥沙颗粒受力分析和能量守恒定律,以处于稳态的泥沙颗粒为参照物,构建了泥沙颗粒水沙界面能量耗散物理图形;建立了考虑挟沙水流运动黏性系数和紊动黏性系数的泥沙群体沉速显式表达式,并采用黄河流域典型黏性泥沙红色砒砂岩颗粒开展了泥沙群体沉速试验研究。结果表明:红色砒砂岩组成的含沙水体中泥沙群体沉速整体随含沙量增大而减小并逐渐趋于定值;当垂向平均含沙量为0.34~0.45 kg/m3时,泥沙群体沉速表现为随含沙量的增加而增大。采用试验数据对建立的公式进行验证,公式能较合理地表达水流黏性和尾流分离对泥沙颗粒沉降阻力的影响。研究结果可为黄河流域黏性泥沙淤积和输移规律研究提供参考。

     

    Abstract: Examining the settling velocity characteristics of cohesive sediment, comprising cohesive minerals within the Yellow River Basin, involves constructing a physical graph depicting the energy dissipation at the water-sediment interface of sediment particles. This construction incorporates force analysis and the energy conservation of sediment particles. The explicit expression for sediment group settling velocity is derived, utilizing the kinematic viscosity coefficient and turbulent viscosity coefficient of sediment-laden flow. This formulation effectively captures the influence of flow viscosity and wake separation on sediment particle settling resistance. Validation of the theoretical framework is achieved through settling velocity tests conducted on representative cohesive sediment, specifically red arsenic sandstone particles, within the Yellow River. The results indicate a monotonic decrease in the group settling velocity of red arsenic sandstone in sediment-laden flow with increasing sediment concentration, ultimately reaching a constant value. Conversely, for vertically averaged sediment concentrations ranging from 0.34 to 0.45 kg/m3, the group settling velocity consistently increases with sediment concentration. The theoretical analysis aligns with experimental observations, and the formulated expression is substantiated by collected data. This comprehensive study serves as a valuable reference for understanding the dynamics of deposition and transport of cohesive suspended sediments in the Yellow River Basin.

     

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