الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 133 |  |  |
| | | from | 133 | | |
Abstract
This research deals with using geogrids as soil reinforcement. A series of uniaxial and pull-out tests were performed on four different types of geogrids including two high density polyethylene, and two polyester geogrids. The in-soil stiffness was calculated using pull-out tests. It was compared to the in-isolation stiffness resulted from the uniaxial tests. The stiffness of geogrids depends on the polymer type, test rate, and ambient temperature. Thermal ageing was used to investigate the long-term behavior of the geogrids. Uniaxial and pull-out specimens were aged in a forced air oven at 90oC. The effect of ageing on the in-isolation stiffness and in-soil stiffness was investigated.
The thesis consists of Five chapters and three appendices:
Chapter (1) is the introduction to this research; it discusses the importance, the scope, and the main objectives of the research.
Chapter (2) is a literature review for previous related studies. It describes the previous studies performed on geogrids to investigate its behavior, whether in isolation or in-soil. Different approaches used to study the geogrid behavior in soil are discussed. The degradation of the geogrid on long term and the different tests performed to investigate this phenomenon are highlighted.
Chapter (3) presents a description of the materials used and the experimental work performed in this study. Different tests were performed and discussed in this chapter to obtain the sand and geogrid properties. Also, the uniaxial test, the pull-out tests, and thermal ageing procedures are discussed.
Chapter (4) comprises the results and analysis of the uniaxial and pull-out tests performed on uniaxial geogrids. The effect of thermal ageing on the geogrid stiffness is discussed whether in-isolation or in-soil. The improvement of the geogrid stiffness due to soil confinement is also calculated in unaged and aged conditions.
Chapter (5) presents the summary and the conclusions of this research and suggestions for future studies.
Appendix A includes all the results of laboratory tests that were performed on sand including sieve analysis, modified proctor tests, and direct shear tests.
Appendix B includes the uniaxial tests that were performed on unaged geogrid specimens to obtain the geogrid properties. The failure modes of the four geogrids in unaged and aged conditions are presented.
Appendix C discusses the working mechanism of the pull-out apparatus components. The pull-out tests raw data and failure modes are also included.