弱动力水流中粘性泥沙作用下水流流速沿垂线分布的试验研究

采用玻璃水槽试验的方法探讨了弱动力水流中粘性泥沙作用下水流在水流条件、含沙量及水质条件共同影响下,流速沿垂线的分布规律.结果表明:弱动力水流流速的垂线分布有其自身的特点,流量较大或含沙量较小时,都基本遵循对数分布规律;流量较小且含沙量足够大时,流速的垂线分布呈横向抛物线形,并出现明显的分层现象;此现象出现后,当含沙量较大、流量减小,或流量较小、含沙量增大时,流速极大值增加、位置向床面下移,流量较小、含沙量较大时,随着钙离子浓度的增加,流速极大值增大,且其位置更贴近床面.

Experimental study on vertical distribution of flow velocity in weak dynamical flow with cohesive sediment

Based on flume experiments,this paper studied the vertical distribution of flow velocity in weak dynamical flows with cohesive sediment effect.The results indicated that the vertical distribution of flow velocity has the following characteristics:(1)The distribution basically accords with the Logarithm Rule if the discharge is big or the sediment concentration is low;(2)The distribution profile will develop into a transverse shape of parabola and appears the phenomena of layer flow if the discharge is small and sediment concentration is high;when this special movement emerges,if discharge reduces with higher sediment concentration or sediment concentration increases with less discharge,the maximum value of the flow velocity will increase accordingly,and its location will move more closely to the river bed.The maximum value becomes even bigger and the location moves much closer to the bed with the increase of Ca~(2+) concentration if the discharge is small and sediment concentratim is high.