| 摘要: |
| 浮泥在海岸、河口及水库中广泛分布，对区域生态、环境和航运等产生显著影响。在不同机制下形成的浮泥，它们的特性也会有所区别。利用大型水箱进行粘性泥沙絮凝沉积试验，收集床面淤积物，并进行流变测试，分析泥沙絮凝对浮泥密度和流变特性影响。结果表明，随紊动水体中絮团粒径的减小和分形维数的增大，形成的浮泥密度将增大，浮泥的屈服应力、粘滞系数呈幂律增长。絮体中的孔隙导致沉积形成的浮泥的结构强度减小，使得浮泥流变曲线丢失了固-液过渡阶段，在到达临界点时直接发生屈服变形进入液态阶段。考虑泥沙絮凝的影响后，在密度大于1110 kg/m3时，浮泥的屈服应力、粘滞系数明显减小，流动指数增大。该研究可为大型水库淤积数值计算提供理论基础。 |
| 关键词: 浮泥 流变试验 絮团粒径 分形维数 流变特性 |
| DOI： |
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| 基金项目:国家自然科学(52109077)；重庆市自然科学(cstc2021jcyj-msxmX0490) |
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| Experimental study on the effect of cohesive sediment flocculation on the rheological characteristics of fluid mud |
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liu jie1, zhou yang san2,3, zhou peng4, xiao yi1
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1.National Engineering Research Center for Inland Waterway Regulation，Chongqing Jiaotong University;2.School of River &3.Ocean Engineering，Chongqing Jiaotong University;4.Hubei Communications Planning and Design Institute Co., Ltd
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| Abstract: |
| Fluid mud is widely distributed in coasts, estuaries, and reservoirs, with significant impacts on regional ecology, environment and navigation. The characteristics of fluid mud formed under different mechanisms can vary considerably. In this paper, a cohesive sediment flocculation deposition experiment was conducted using a large water tank to collect flocculated sediment and perform rheological tests to analyze the effect of sediment flocculation on the density and rheological properties of fluid mud. The study indicates that the density of deposited fluid mud increases as the size of floc in turbulent water decreases and the fractal dimension increases. The yield stress and viscosity coefficient of the fluid mud also increase in a power law. The structural strength of the deposited fluid mud decreases due to the presence of floc pores and the disruption of the floc structure. As a result, the rheological curve of the fluid mud skips the solid-liquid transition stage and directly transitions into the liquid stage when it reaches the critical point. After considering the effect of sediment flocculation, it was observed that the yield stress and viscosity coefficient of fluid mud decreased significantly, while the flow index increased at densities greater than 1110 kg/m3. This study provides a theoretical basis for numerical simulation of siltation in large reservoirs. |
| Key words: fluid mud rheological test particle size of flocs fractal dimension rheological characteristics |
