The Transfer Characteristics Of Axial Load In Particle System

Granular matter can be seen everywhere in our daily life,With its complex properties of the granular system research,Many physicists begin to research in recent years.Meanwhile,Granule storage has become a major research too.The design of the granary still use Janssen theory mostly,but the Janssen model is based on three assumptions,there are few experiment can directly establish those assumptions correct or not.In this paper,Janssen Ratio is measured in a dense granular pack by using pressure sensitive birefringent optical properties materials making silo walls.The pressure on the lateral walls as a function of the depth of the pack with axial load under gravity is measured by photoelastic method.The samples are prepared by“point source”method with and without tapping.A non-monotonic distribution of the side pressure along the depth is found.Numerical simulation is performed and shows qualitative consistency with the experimental finding.The peak depends on the load,partical density,particle size and the preparation methods of samples.In addition,The apparent weight of the sample is measured for different filling heights and for different top loads.Comparing with the normal stresses on the silo wall for different heights,we obtain the Janssen Ratio^J?28??xx/?zzas a function of height.We find that although uJ=0.11 is a constant as is expected,the Janssen Ratio is height dependent.It becomes height independent only when the top load is large enough.