三峡坝区非粘性均匀花岗岩砂粒起动条件研究

由花岗岩风化而成的砂粒质地粗，石英、长石颗粒的粒径较大。通过实验室对非粘性均匀花岗岩砂粒起动条件研究，得到特定条件下不同砂粒粒径在薄层水流紊流流态时的起动流速。实验结果表明，同一粒径组的非粘性花岗岩风化砂粒随底坡坡度的增加其起动流速变小；同一边界条件时，细粒砂随坡度的增加，其起动流速降低幅度较小，相应地随着砂粒粒径变大坡度增加时，其起动流速降低幅度较大。

Incipient motion conditions of noncohesive uniform granite grains in Three Gorges dam region

The leading feature of sand grains of weathered granite is rough tissue with large quartz and feldspar crystals. Through laboratory experiment incipient motion conditions of noncohesive uniform granite sand grains under a thin layer of turbulent flow have been studied for a particular case. Test results show:for the same grain size groups the flow velocity relating incipient motion of these granite sand grains decreases as the bed slope increases;for the identical boundary condition groups the rate of incipient velocity decrease during bed slope growth for fine sand grains is smaller than that for coarse sand grains.