Study On Cavity Effect In Granular Matter

The change of force chain influenced by cavity effect in granular matter is studied experimentally. When pull out a rod from granular matter, that should exist a cavity under it and the force chain structure will be changed, the change should be studied by the friction of the rod. Based on former research, we improved our experimental set, measured the cavity effect of different depth of the filling granules(viz. the depth of the cavity), different diameter of the granules, different diameter of the container and different diameter of the rod. We found that the granular matter is influenced by the cavity's depth only, and this relationship is independent of the diameter of the granules, diameter of the container and diameter of the rod. By using origin soft, We found the relationship between the breakdown time t and thecavity's depth h is t= Aexp(h/λ.) +B and A=7.57±0.3 , B=2.45±0.4 ,λ=70.00±0.7. This expression could be used in the other granular system. We do an two-dimension experiment at the same time, to understand the inside situation of the granular matter clearly.