| dc.description.abstract | This dissertation focuses on the development of a mechanics based soil-roller
interaction model intended to determine the degree of compaction of the top soil layer.
The model was calibrated with, and compared to, soils data obtained from field and
laboratory tests. The model contained 2 soil layers, but can be expanded to include
additional layers.
This study concludes that the developed soil-roller interaction model is capable
of accurately determining the degree of compaction of the upper soil layer through back
calculation of the soil modulus values. The model was able to reach convergence
between the calculated and measured values of roller drum deflection through a
regression analysis of soil stiffness and damping characteristics. The final values of the
stiffness and damping characteristics needed to achieve a 1 percent difference between the
calculated and measured values of roller drum deflection fell within expected ranges for
the type of material tested.
Part of this study included a sensitivity analysis of the input characteristics. The
results of the sensitivity analysis revealed that the output of the model was highly
sensitive to the mass of the second soil layer and to the elastic and plastic stiffness
characteristics within both soil layers, but relatively insensitive to the mass of the first
soil layer. The lack of sensitivity to the mass of the first soil layer means that large
changes in the layer mass, and by extension the density, will have little effect on the
output of the model. This characteristic is a drawback for conventional, density based specifications. However, specifications based on installing fill to the designed values of
stiffness or modulus could benefit from the model.
Much of the initial difference between calculated and measured roller drum
deflection was probably caused by the difficulty in determining accurate starting values
for the soil stiffness, damping and mass model characteristics. Future research should
focus on ways to determine accurate values of the required input characteristics. | en |
