Three different types of assay were conducted by varying the mode of silo discharge. In the first kind of assay, the silo was completely emptied following a period during which the stored material remained static. In the second type, a small amount of material was unloaded before interrupting the discharge, and in the third type, discharge was effected in several stages. We also studied the influence of variations in pressure on discharge speed.
This study shows that variation in the discharge flow rate is not associated with a further increase in pressures and that the state of overpressure attained during discharge is essentially due to compaction or an increase in the specific weight of the material in given areas of the silo. We also observed that the discharge of a small amount of material caused a variation in pressures of the same magnitude as a complete discharge, and that previous pressure levels were not recovered once a partial discharge had been halted. The results of this study are compared with the Eurocode 1, part 4; in all cases, the values obtained were lower than those proposed in the Eurocode.