Abstract
Granular materials are found every where despite they are poorly understood at microscopic level. The main hindrance is how to connect the microscopic properties with the macroscopic behavior and propose a rigorous unified theory. One method is to test the existing theoretical models in various configurations. In this connection we have performed experiments in different configurations of granules in a silo to determine the validity of the Janssen model under such arrangements. Two and four layered structures of different bead diameters are prepared. The effective mass at the bottom of the container in such cases have been measured. Moreover, the investigation of layered structures reveals that such configurations also follow well the Janssen model. An interesting percolation phenomenon was observed when smaller beads were stacked on larger ones, despite the model remained valid. Furthermore, it is demonstrated that Janssen law holds for larger bead diameters.