الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 200 |  |  |
| | | from | 200 | | |
Abstract
Storage and handling of bulk materials in soils are essential processes in industries which utilize raw materials and products in granular form. Proper design of efficient and safe silos requires the determination of the flow properties of the bulk material and the implementation of these properties in the stress analysis to determine the design loads in the silo.
In this study, the flow properties of different powders are determined using several testing equipment such as Hosokawa powder characterization tester and Jenike shear tester. Results show that the addition of calcium lignosulfonate, a waste product from the paper industry, to the hydrate powders improves the overall flowability of the modified hydrates. Also, the cohesive strength of the hydrates as the weight percentage of the lignosulfonate in the modified hydrates increases. Moisture content is found to have a strong effect on the flow properties of the tested powders. As the moisture content increases from 0 to 7% the flowability of the powders decreases by about 15%.
The density piecewise linearization, DPL, is a new technique developed in this study and implemented in the stress analysis of bulk soilds in silos using the method of differential slices. The DPL technique accounts for the variation of the bulk density of compressible powders while being subjected to consolidating pressures in soils. Wall pressures obtained by this technique are found to be 30 to 40% greater than those obtained by the classical method of differential slices where constant bulk density is assumed for the materials.
Aparametric study is conducted to evaluate the effect of several parameters on the stress distributions in soils. The parameters of the study are effective angle of internal friction, angle of wall friction, surcharge pressure, depth -to-diameter ratio of the silo, and angle of hopper. The study shows that the effective angle of internal friction has no major effect in the value of the maximum wall presure predicted in the silo. Surcharge pressures and the angle of wall pressure are found to be the most critical parameters that affect the value of the design pressures in silos.