Dynamic Pressure of Granular Material in Deep Bins

Experiments on full-size silos and laboratory tests show that the vertical cracks that sometimes appear in deep bins are not the result of poor construction, but rather the neglect of the dynamic pressures during their design. These pressures are manifest during the emptying of deep bins, with discharge openings centrally located. Experiments have shown that the lateral dynamic pressure may reach a value as high as 2.4 times the values obtained by Janssen's theory. During bin discharge, granular flow may be either dynamic, with the resulting large pressure increases, or nondynamic without pressure increase. In order to assure against dynamic pressure failure, bins should either be designed for larger lateral pressures than those obtained by the static methods of design or one of the following installations should be made. Anti-dynamic tube placed in the center of the bin; interior rings attached to bin walls throughout the depth of the bin; or openings provided into adjacent bins at several levels, and the contents discharged through one of the bins, preferably through the one centrally located.