Use of Geogrids for Limiting Longitudinal Cracking in Roads on Permafrost

Longitudinal cracking of road embankments results from lateral movement of the subbase which creates a subsurface void space. The void spaces propogate to the surface causing cracks and voids. This is hazardous to motorists and expensive to repair. This thesis examines the use of geogrids to limit lateral spreading thereby preserving safe and useable road surfaces. A field experiment, a full-scale laboratory experiment, a soil arching experiment, and behavioral and theoretical analyses are presented. Soil arching forces are quantified and developed using an experiment based on work done by Terzaghi and Kienzl. A theoretical analysis for quantifying the shear force redistribution to be used for geosynthetic embankment systems, was derived from the Soil Arching Experiment. Relationships of load, embankment resistance, deflection and geometric factors are presented. A comparison of geogrid performance to a geotextile performance for the given relationship is presented as well.Abstract - iii Dedication - iv Table of Contents - v List of Figures - viii List of Tables - x Acknowledgements - xi Definitions of Symbols - xii I. Introduction - 1 II. Theoretical Background - 7 2.1 Performance During Lateral Spreading Without Traffic Loading - 7 2.2 Analysis of Performance Over Crack With Traffic Loading - 11 2.2.1 Load Resistance Analysis - 12 2.2.2 Deflection Analysis - 14 2.2.3 Effects of Geosynthetics Used - 14 2.2.4 Soil Arching Theory - 15 III. Theoretical Behavior of A High Modulus Geogrid - 21 IV. Experimental Models, Methodology and Analyses - 25 4.1 Field Experiment - 25 4.1.1 Test Configuration and It's Operation - 26 4.1.2 Materials and Equipment - 27 4.1.3 Test Section Construction - 28 4.1.2 Test Sequence - 31 4.2 Full-Scale Laboratory Experiment - 32 4.2.1 Test Apparatus and It's Operation - 32 (the second page of the table of contents is missing) Appendixes Appendix A-Properties of Laboratory Soil - 88 Appendix B-Properties of Geosynthetic Materials Used - 93 Appendix C-Secant Modulus - 100 Appendix D-Glossary of Terms - 10