关键词: 内摩擦角, 含水率, 粒径, 天然坡角

Abstract: The sand particle friction property is one of the most important factors affecting the morphology of sand dunes. It has practical significance to discuss the bed morphology, the mobility, the stability and the protection of sand dunes. In this paper, we did some experiments to explore the quantitative relationship between internal friction angle and particle size, water content and slope angle. The results showed that when the particle size varied from <0.125 mm to 0.315-0.4 mm, the sand particle internal friction angle decreased from 32.25 to 28.06. When the sand particle size varied from 0.315-0.4 mm to 0.63-0.8 mm, the sand particle internal friction angle increased from 28.06 to 31.47. Smaller particles have larger surface which makes the contact area between particles larger. Larger particles have obvious effect of interlock function due to their rough surface. When the water content varied from 0 to 15%, the sand particle internal friction angle increased from 29.07 to31.84. When the water content varied from 15% to 20%, the sand particle internal friction angle decreased from 31.84 to 30.75. Water makes sands show some cohesion which makes the internal friction angle larger, but lubrication weaken the friction between particles when high water content. The internal friction angle and the slope angle are natural reactions of sand particle friction characteristic. The maximum slope angle is equal to the internal friction angle.

Key words: internal friction angle, water content, particle size, slope angle