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基于水深与流量的变化率提出了反映水流非恒定强度的无量纲参数P。利用水槽非恒定流输沙同步测试系统试验研究了非恒定流作用下砾石推移质的输移特性。试验资料分析表明,非恒定流作用下的砾石推移质输移具有明显的随机性、间歇性与阵发性。水流的非恒定性对输沙率峰值的脉动性有影响,对P>0.32的强非恒定流而言,若输沙率样本数少于20,将会给输沙率结果带来较大的偏差。非恒定流作用下输沙率与水流要素变化具有不同步性,并与水流非恒定强度有关。P>0.32时,输沙率峰值一般滞后于流速峰值;当P<0.32时,可能出现输沙率峰值先于流速峰值的现象。非恒定流作用下砾石推移质平均单宽输沙率(或输沙量)与单宽流量(或径流量)、非恒定强度参数P有关,随P的增强而加大。
Based on the rate of change of water depth and flow rate, dimensionless number P, which reflects the unsteady intensity of water flow, is proposed. Using the unsteady flow of sand in sediment transport test system, the transport characteristics of gravel mass transfer under unsteady flow were studied. Experimental data analysis shows that gravel plutonium transport under the action of unsteady flow is obviously random, intermittent and paroxysmal. The unsteady flow has an impact on the pulsation of the sediment transport rate. For a strong unsteady flow with P> 0.32, if the sediment transport rate is less than 20, it will bring a larger deviation. Under the action of unsteady flow, the rate of sediment transport and the variation of water flow elements are not synchronous, and are related to the unsteady intensity of water flow. When P> 0.32, the peak value of sediment transport rate usually lags behind the peak value of flow rate. When P <0.32, the peak value of sediment transport rate may precede the peak value of flow rate. Under the influence of unsteady flow, the average single-width sediment transport (or sediment discharge) of gravel piles is related to the single-wide flow (or runoff) and the unsteady strength parameter P, and increases with the increase of P.