浑水、含沙水流、泥石流的鉴别

Classification of muddy water, sediment laden flow and debris flow

本文从连续介质的流变曲线出发，从理论上探讨了伪一相流互相流的力学特性，两相流中表现宾汉屈服剪应力随含沙量的变化以及区分牛顿体，非牛顿体的含沙量界限，和高含沙水流与泥石流的动力学区别，给出了鉴别浑水、高含沙水流和泥石流的特征值表．

According to the rheologic equation of continuous medium:When τB= 0,n=1 the medium such as the clear water and the water with a small percentage of sediment is called Newtonian fluid,when τ≠0,k=ηand n=1,the medium is classified into Bingham fluid or non-Newtonian fluid, and all above fluids can be called pseudo-one-phase fluid.However,when the fluid contains some amount of granulars, it can be classified into two-phasefluid with similar equation but different internal mechanisms as above mentioned.for Binghan fluid, η=1,k=η+ε,η=rigid coefficient, ε=eddy viscous coefficient.In sediment laden flow, τB is different and the roles of its compositions are different for different sediment concentrations.When volume concentration C<0.44.i. e.,S<108kg/m3,τdispersed/τstriked>10,the sediment laden flow is Newtonian; when c=0.17, the flow becomes Bingham, i. e., non-Newtonian fluid; and when C>0. 35,it belongs to debris flow.The hyperconcentrated flow is mechanically different from debris flow. When e>0.7,thesolid particles are suspended by the force from liquid phase, and when e<0.7,i.e.,s>810kg/m3, the coarse particles transported as bed load are carried by potential energy of solid phase.Therefore,e=0.7,c=0. 3 and sediment concentration=810kg/m3 are the key limitation.If S>810kg/m3,the hyperconcentrated flow would be gradually transformed into thin debris flow and debris flow with increasing of sediment concentration.The difference between hyperconcentrated flow and debris flow lies in the acting force.In the hyperconcentrated.flow,the solid particles are suspended by the force from liquid phase.When S>1160kg/m3,the flow belongs to thick debris and the particles are supported by striking force between particles instead of the force from liquid phase.When S>2180kg/m3, the solid particles are so dense that the particles would be supported by τB.These features have been proved by the date from the middle Yellow River and its tributaries,and the Jiangjia Gully.Introducing the parameters of CJ and τ0.(γmhJ),a table has been established which can be used to distinguish the muddy,the hyperconcentrated and the debris flows.