细颗粒原状土起动流速试验研究

为了得到更为客观科学的泥沙基本活动规律,利用有压矩形管进行了细颗粒泥沙起动试验。试验结果表明,管内水压力对细颗粒泥沙的起动有重要影响,水压力越大,管中泥沙起动断面平均流速和起动切应力越大。根据有压矩形管的水流分布特性和水压特点,将矩形管中水流转换为普通明渠水流,转换得到的明渠中泥沙起动垂线平均流速与试验矩形管中泥沙起动断面平均流速基本相同,验证了利用有压矩形管进行细颗粒泥沙起动流速试验的可行性和代表性。在试验矩形管与实际明渠的泥沙起动流速转换过程中,并未考虑不同水柱高度下曼宁糙率系数的变化,这方面还有待进一步研究。

Experimental study on incipient velocity of undisturbed fine particle soil

The incipient motion of fine sediment is tested in a pressured rectangular pipe with different water head. The results show that the water pressure greatly influences the incipient motion of fine sediment in that the incipient sectional mean velocity and the incipient shear stress increase with water pressure. The flow in rectangular pipe can be converted to the flow in ordinary open channel according to the characteristics of flow distribution and water pressure in rectangular pipe. The converted vertical average velocity in open channel is basically the same as incipient sectional mean velocity in rectangular pipe. The results have verified the feasibility and representativeness of the study on incipient motion of fine sediment in rectangular pipe. The change of Manning roughness coefficient under different water head has not been considered in the conversion process of incipient velocity of fine sediment from rectangular pipe to open channel, so the laws in this area need to be further researched.