泥石流细颗粒浆体的有效浓度

The Effective Concentration of Fine Particle Slurry of Debris Flow

粘性泥石流和稀性泥石流中的细颗粒含量基本相同,但它们的浆体浓度和物理力学性质却差异甚大.本文将从泥石流的颗粒组成出发,分析粗颗粒在泥石流中的作用,提出能够反映粗颗粒影响的有效浓度概念,给出一个计算实例,以说明它的计算方法.

It is generally thought that viscous debris flow has a higher fine particle content than non-viscous debris flow, so its slurry concentration is much higher than the latter. In fact, the research shows that the fine particle content of viscous debris flow is nearly the same as that of non-viscous debris flow. For example in our paper, their fine particle contents (d<1.0mm) both are 500~800kg/m2. Now that the contents are the same approximately, why are their slurry concentrations very different? Obviously, this is caused by different coarse particle content, the coarse particle content of viscous debris flow is much higher by comparison.Naturally, because coarse particles reduce the space (or volume) occupied by fine particle and water, they can raise the effective concentration of fine particle slurry, thus influencing indirectly the physical characteristics of debris flow. These are the important contribution of coarse particles to debris flow.The coarse particles can raise the concentration of fine particle slurry. On the contrary, fine particle slurry with higher concentration is able to decrease the settling rate of coarse particles and make them maintain in slurry. Just the action of coarse and fine particles together can engage viscous debris flow to reach very high sediment concentration.The paper gives a concept of effective concentration C(?)=Vf/(1-Vc),here Vf is the volume of fine particles per unit volume and Vc is the volume of coarse ones. Effective concentration can reflect the influence of coarse particle. Basing this concept, many phenomena of debris flow are easy to be explained. At last, an example of calculation mothed of C(?) is introduced.