吹填中疏浚泥颗粒运移及分选若干关键问题的探讨

为了确定处理面积和选择合理的处理方法,以节约工程成本和达到良好的处理效果,需要对吹填时疏浚泥颗粒在堆场内运移及分选的规律进行研究。以泥沙运动力学为理论基础,结合南水北调东线江苏段淮安金宝航道N1疏浚泥堆场的现场调查和试验结果,对吹填时疏浚泥颗粒运移及分选若干关键问题(如堆场分区、疏浚泥分层特性、疏浚泥沉降行为、疏浚泥流体类型等)进行了深入的探讨,得出如下结论:①美国的疏浚工程手册EM1110-2-5027以粒径0.075 mm将堆场分为粗颗粒区和细颗粒区是合理、可应用于国内疏浚工程实践的,颗粒分选发生于细颗粒区;②吹填过程中堆场内上层泥浆一般为牛顿体和过渡区流体,淡水环境下颗粒的沉降行为主要为絮凝沉降,颗粒运移及分选主要发生于上层泥浆中,参与分选的颗粒主要为悬移质;③疏浚泥颗粒分选是在一定的水动力条件和堆场边界条件下,细颗粒在液相泥浆中运移时,由于粒度的差异而产生的分区域沉降行为。

Discussion on Some Critical Problems of Transport and Sorting for Dredged Soil Particles during Dredging

In order to determine the area needed to dispose and select reasonable disposal methods, transport and sorting of dredged soil particles during dredging is needed to study urgently. In this paper, some problems (including zoning for dredged disposal areas, layering for dredged slurries, settling behaviors of dredged slurries and fluid types of dredged slurries etc.) on transport and sorting of dredged soil particles and mechanisms are proposed to discuss based on the theory of dynamics of sediment movement using some results of field investigation from N1 storage yard of dredged slurry near Jinbao Channel which belongs to a part of Eastern Route of Water Diversion from South to North in China, and some helpful conclusions are obtained: (1) the dredged soil disposal area is divided into two zones roughly including fine-grained zone (d<0.075mm) and coarse-grained (d>0.075mm) zone in the manual EM1110-2-5027 which is reasonable and can be suitable for that of inland in China; (2) the upper layers of dredged slurry are Newtonian fluid or transition zone fluid with weakly cohesive generally, the settling behavior of the particles under fresh-water environment in the upper layers is discrete settling, in which sorting of particles takes place, and main materials joining sorting are suspended loads; (3) sorting of dredged soil particles during dredging is a settling behavior of particles with different sizes that are carried by liquid phase to different regions of the dredged soil disposal area, which is restricted by flow conditions and boundary conditions of dredged soil disposal area.