非均匀沙起动机理及起动流速

首先指出所谓宽级配泥沙，包括卵石等的起动流速必须按非均匀沙来研究。进而阐述了非均匀沙推移质低输沙率规律，导出了其理论表达式，并进行了数值计算。根据这个低输沙率关系，只需要选定起动标准就能确定起动流速。接着引进了非均匀床沙综合起动流速概念，给出了综合起动流速公式，并以实例说明其合理性。最后讨论了非均匀沙处于起动状态时的分选情况。

Incipient Mechanism and Incipient Velocity of Nonuniform Sediment

At first, it is pointed out that in the study of incipient velocities of sediment, with a wide grading range including pebbles, the sediment should be regarded as one of nonuniform. And then, the law of low transport rate of the nonuniform bed load is presented, its theoretical expression is derived and the calculated results and given. According to this relationship of low transport rate, as soon as the incipient criterion is being selected the incipient velocity may be determinde. After establishing the concept of synthetical incipient velocity a crresponding formula is given and some field data are used to verify its rationality. Finally, the sorting state of nonuniform sediment in incipient motion is discussed.