The Angle Of Repose For Inclination Granular Orifice Flow

The angle of repose is an important macroscopical parameter that reflects the internal mechanics relationship of granular matter, and it server as an evaluation index of fluidity and slope stability. For medium mechanics, mechanics of sediment transportation,and the practical problems such as buckling failure of bank slope, sandbar, the research of the angle of repose of granular matter not only has scientifically theoreical significance, but also has engineering application values.Systematic experimental study on inclined orifice flow and the measurement of the angle of repose has been carried out. We measured the flow rate of a granular system (glass beads) discharged from an inclined orifice for various inclination and orifice diameters under the action of gravity. The experimental results verified that different the orifice sizes, the fluxes(Q) all vary linearly with cosine of the inclination angle, and the critical angle(?c) of flow ceasing increase linearly with ratio between grain and orifice diameter. The resulting the angle of repose in the limit of infinite orifice diameter. We compared the angle with the inclined angle of direct measurement when the flow rate is equal to zero(?s?), the repose angle of sample granular heap on the smooth surface spontaneously(?r), and the internal friction angle obtained from direct shear experiment(?). It is found that the values of ?c?,?s?,?r,? are very similar. This work show that the measurement of the extrapolation of flux using inclined orifice flow can exclude the measuring error effectively, establishing a kind of precise measurement method of repose angle.