Mechanical properties of granular materials as related to loads in cylindrical grain silos

Abstract

Physical quantities thought to be pertinent to the development of loads in cylindrical silos filled with granular materials were identified. The principles of similitude and dimensional analysis were used to formulate, organize, and analyze data from experiments in order to arrive at prediction equations for loads in silos. Dimensionless Π-terms were used for the prediction equation. Experiments were carried out to investigate the validity of Janssen;s constant, k, the ratio of the horizontal to the vertical pressure in granular materials en-masse. It was concluded that k is not an independent material property. The study revealed that particle size (λ), height-to-diameter ratio (H/D), relaxation modulus (E(t)) and grain depth (z) are pertinent to the development of pressures in grain filled silos. Inertial effects were found to be unimportant to the development of pressures in silos. The phenomenon of dynamic overpressure in emptying silos was observed.