堆场疏浚泥颗粒分选规律及机理

Grain sorting laws and mechanisms in reclaimed land of dredged slurries

为了确定大面积高含水率疏浚泥堆场的处理面积和选择经济、合理的处理技术,对吹填时堆场内疏浚泥颗粒的分选规律及机理进行了研究.系统调查了南水北调东线江苏段金宝航道N1疏浚泥堆场,并对距离吹填口不同位置、不同深度的疏浚泥进行取样.土样的颗粒分析试验结果表明:堆场内疏浚泥颗粒粒径随着距吹填口距离的增大而减小,黏粒(d<5μm)含量沿程逐渐增大,粒径大于10μm的颗粒含量沿程逐渐减小,粒径介于5～10μm之间的颗粒含量沿程基本保持不变,在水平方向表现出明显的分选性;疏浚泥颗粒在垂直方向上分选性较弱,且分选规律较差.以泥沙运动力学和高含沙水流运动学为理论基础,通过分析吹填过程中不同粒径的颗粒在堆场内的运移规律,对堆场疏浚泥颗粒的分选机理进行了探讨,明确了疏浚泥浆的含水率、颗粒级配、尺寸以及水动力条件等是影响疏浚泥颗粒分选的主要因素.

In order to determine disposal areas and select reasonable disposal technologies,laws of grain sorting and mechanisms for dredged slurries with high water content in large reclaimed land are studied.The N1 storage yard of dredged slurries near Jinbao Channel which belongs to a part of eastern route of water diversion from South to North in China is investigated,and soil samples at different distances from filling inlet and different depths are obtained.Results of grain size analysis for soil samples show that the grain size of dredged soils decreases along the horizontal direction.The content of clay particles（d5μm） increases along the horizontal direction;the content of grains with sizes more than 10μm decreases along the horizontal direction,while the content of grains with sizes between 5 and 10 μm maintains almost the same.Grain sorting characteristics are prominent in horizontal direction,yet grain sorting characteristics are not obvious and sorting laws are poor in vertical direction.Laws of movement and transportation for grains of different sizes are analyzed based on dynamic theory of sediments and kinematics of high sediment-laden flows.Mechanisms of grain sorting for dredged slurries are discussed,and it is determined that major factors affecting grain sorting are moisture contents of dredged slurries,grain compositions,grain sizes,and flow conditions etc.