# title
Goudarzi, Anahita (2019-05). Steel and Geosynthetic Reinforcement-Soil Interaction. Doctoral Dissertation.

# abstract
For the last 50 years, the use of reinforced soil systems has increased significantly. As such it is important to gain an in-depth understanding of the soil-reinforcement interface properties for designing and simulating purposes. The interaction between the soil and the reinforcement can be complicated, depending on the properties of the soil and the reinforcements. The goal of this research is to investigate the soil-reinforcement interaction during pullout tests and during direct shear tests using experimental and numerical modeling. The influence of the rib spacing, soil density, grain size, and confining stress on the interface shear strength and pullout force were evaluated. Furthermore, the contribution of the soil passive resistance due to the ribs to the pull-out force was quantified.   This study focused on the behavior of the smooth and then ribbed steel strips and of the geosynthetic reinforced soil systems. The first step of this research was to undertake an in-depth review of the published literature regarding the reinforcement/soil interaction. Then geotechnical laboratory tests including small and large direct shear tests and large direct, simple shear tests on selected soil materials were conducted. After that, over 200 laboratory tests were conducted including large direct shear tests and pullout tests to investigate the interaction between various reinforcement types and various soil materials. A comparison study utilizing these two types of test was conducted to investigate the underlying mechanism of soil and reinforcement interaction under different condition. The final step of the research was to conduct numerical simulations of the large direct shear test and pull out test performed in the laboratory by using FLAC3D by Itasca Inc. The numerical simulation was first calibrated by comparing the experimental data and the simulation data including the soil/reinforcement interaction mechanism.  The results showed that the numerical results are in good agreement with the experimental results. The influence of the number of ribs on steel strip reinforcements is more significant at a lower depth of embedment, for dense soils, and soil aggregates with D80 lower than the ribs height.