非均匀风沙起动风速研究

onsidering the hiding exposure action among non-uniform sands, the common tangential angle of bed material, whose common tangential line passes through the tangential point of the particles, is introduced in this paper as a parameter to indicate the position of the particles, then, the relation between the common tangential angle and exposure degree is established. Based on the critical condition that the particles on the sand surface is to move, variation of common tangential angle is then used to determine a criterion for non-uniform sand incipience. Relating the hiding exposure action with the position of the particles on the bed and its grain size during incipient motion, based on the static conditions of sand critical incipience, a formula for computing the threshold wind velocity of non-uniform sand is derived. The threshold wind velocities obtained from this formula are compared with those got by experimental measurement, and the correlative coefficient between them is 0.974, which suggests that the formula is reasonable.