| The primary objective of this thesis is to investigate the hypothesis that soil confinement in sand can increase the stiffness of a biaxial polypropylene (PP) geogrid reinforcement material to values greater than those deduced from conventional in-air testing. To meet the primary objective of this investigation, the thesis first presents a review of the literature with special emphasis on previous in-soil pullout testing methodologies and interpretation of results. Lessons learned from in-soil test equipment reported in the literature, including pullout boxes, were used to design the test box used in this investigation and to overcome deficiencies in previous related work. A unique feature of the test box in this investigation is that the soil-embedded portion of the geogrid specimen is visible and in-situ reinforcement strains can be calculated from reinforcement deformations recorded using two different digital camera techniques. (Abstract shortened by UMI.)... |
