The Research Of The Initlation Thresholds Of Blown Sand

This dissertation mainly focus on two problems as follows:aimed on the shading interaction of non-uniform sand particles, proposed a formula of non-uniform sand's threshold velocity by considering the relative exposure degree and particle composition. Because of the complexity and randomicity of the non-uniform sand's threshold velocity on slope, the slide balance mode was used to constitute the formula of non-uniform sand's threshold velocity of slope, then this formula was validated and analyzed. Based on above analysis, a formula with consideration of air turbulence and threshold level was established through the fuzzy mathematics method and slide balance mode, and simply analysis was made.First using the method of the inhomogeneous sand initiation in silt research for reference, this article starts from the initiation characteristics of the inhomogeneous sand, and defines the exposure degree△and Coefficient of relative exposure degreeξ. And the theoretical analysis has been carried on the values of the exposure degree and Coefficient of relative exposure degree. The result indicates that the relative exposition value of bed surface layer sandstorm pellet is not a constant, but is located in a sector. Then through considering the relative exposure degree and particle composition we propose the concept and expression of additional mass force with reference to the method of sediment threshold velocity and can the formula of threshold velocity are gotten by introducing the relative exposure degree parameter. Compared to the experimental data, we can see that the formula in this paper can show the threshold characteristic of non-uniform sand particles well.At present the theory and experimental study on the movement of inhomogeneous sand on slope face are very few. In this dissertation, through introducing the additional mass force and the slide balance mode, a formula of non-uniform sands threshold velocity of slope is constituted with consideration of the effect of exposure degree. The experimental data is compared with the results from this dissertation for zero slope angle and it is found that the results from this dissertation agree well with experimental data. Based on the formula of non-uniform sand's threshold velocity of slope, we establish the formula with consideration of air turbulence and threshold level through the fuzzy mathematics method and slide balance mode, and simply analysis is then made.