库区浮泥层纵向流速垂线分布特性研究

Study on vertical velocity distribution characteristics of fluid mud layer in reservoir area

水库浮泥是存在于水库底部的一层高含沙水体,流动性较强,直接影响水库淤积形态和水库排沙,研究其运动规律对水库减淤优化调度具有重要意义。根据三峡库区实测泥沙矿物组成和级配资料,配置沙样进行流变试验,以幂律流变模型描述浮泥的本构关系。构建了浮泥运动的速度分布理论模型,通过水槽试验对模型进行了验证,计算结果与试验结果吻合较好。结果表明,浮泥运动速度随浮泥厚度、上层水流流速、床面坡度增大而增大,随浮泥密度增大而减少。沿水深方向浮泥纵向流速分布始终呈抛物线型,表层的浮泥流速要远大于底层浮泥,浮泥纵向流速沿垂向方向不断减少,最底部的浮泥几乎处于静止状态。

Fluid mud in large reservoirs is a near-bottom layer of water body with higher sediment concentration and strong liquidity and directly affects the sedimentation morphology and the sediment discharging of the reservoir.Studying its movement law is of great significance to achieve the optimal operation of reservoir sedimentation reduction.According to the measurement of mud mineral composition and size grades in the Three Gorges Reservoir area,sediment samples were configured for mud rheological t tests,and a power-law rheological model was used to describe the constitutive relationship of fluid mud.A theoretical model for velocity distribution of fluid mud movement was constructed,and the model was verified through flume experiment.The calculation results are in good agreement with the experimental results.The study results show that the velocity of fluid mud increases with the increase of its thickness,upper water flow velocity,and bed slope,but decreases with the increase of fluid mud density.The vertical velocity distribution of the fluid mud always follows a parabolic shape.The velocity of fluid mud on the surface is much greater than that on the bottom,and the longitudinal velocity continuously decreases in the vertical direction,the bottom fluid mud is almost at a standstill.