Research On Geometric Shapes Influencing On Incipient Motion Of Gravel

The mountain river is common in the river, which water and sediment movement characteristics are complex. Incipient motion is a basic problem about river dynamics and sediment movement, there are many domestic and foreign scholars have studied it. So far, the proposed non-cohesive sediment formulas have been more than 100, but it is very less formula which reflected geometric shapes influencing on incipient motion of pebble. So carrying out this research has important theoretical.This paper collected large volume of gravel materials of the Yangtze River in Chongqing. According to the inadequacies about describing particle shapes,this paper puts forward a new kind of parameter——elliptic plumpnessΠ, and analyse the distribution functions of measured gravels.In addition to the impact of depth H, velocity V, slope J and roughnes n,there are other factor to affect incipient motion of sediment,so starting on theoretical and experimental research and summarizing its regularity. Under the influence of quality and shap, two sands show the same phenomenon that standard particles need the maximum q *,bar particles smaller and approximate particles least. Then using the single factor analysis and introducing the elliptic plumpness,this paper deduce the revised formulas which can reflect the influence of particle shape.Finally, analysing the correlation of two kinds of sand incipient motion,it finds that this two different material sediments have little differences and using coal granule instead of natural sand is available.But also noticed the tendency that the S.F. and error between two sands are increased together.So in the test data processing,it should modify the test data on the basis of established relationship,in order to ensure model sand reflect the characteristics of natural sand.