细颗粒泥沙成团起动及其流速的研究

文中首选指出当水深很大时，考虑薄膜水附加下压力的起动流速公式计算的单颗细泥沙的起动流速很大，甚至于远超过３ｍ／ｓ，这与实际资料有相当出入。此外，实际现象还表明这些粘土及细颗粒起动时常常不是单颗的，则是成团进行。由此出发，再考虑粘着力及薄膜水附压力下分析了土块成团起动的临界条件，得到了成团起动的起动流速。

The incipient motion and velocity of aggegated fine particles

Under deep water, the incipient velocity calculated from the formulae for single fine particle under cohesive force and additional pressure of film water is much larger than real one and even more than 3m/s in some cases. Besides, in the nature, sometimes, thefine sediment is aggragated as soil lump or layered soil, nut not in single particle to start moving.In this paper, the critical condition of incipient motion for the aggregated soil under coheslve force and additional pressure of film water is studied, and the incipient velocity is derlved.The critical depth Hk is introduced after comparing the incipient motion of single particle with that of lump and layered soil. In the cases of H(water depth)>Hk,H=Hk or H Hk, the incipient soil is mainly in aggregated structure. The calculation reveals that Hk reduces with the decrease of D0, the size of soil lump, dry density and single particle size, and with the increase of lump ellipticity under certain conditions. In some cases, Hk may be very small and even zero, so that in incipient motion, the sediment will be aggregated in lump or layered soil under any water depth. The formulae for aggregated fine particles have been verified in laboratory, and show good agreement with the observed data.