Digital image correlation for mechanical damage assessment in geogrids: experimental characterization and 3D numerical modeling of soil-geogrid interaction

Mechanical damage to geogrids significantly affects their performance in geotechnical applications, yet conventional testing methods provide limited insight into the complex strain localization mechanisms governing failure behavior. This study presents a comprehensive framework combining digital image correlation (DIC) with three-dimensional finite element modelling to investigate damage effects on the mechanical response of extruded geogrids. A DIC-based experimental approach was developed to characterize full-field strain distributions in both undamaged and damaged geogrid specimens under in-isolation tensile loading, revealing distinct localization patterns and damage-induced stress concentrations that would remain undetected by conventional extensometer devices. The experimental strain data were used to calibrate and validate an orthotropic viscoelastic model that captures the directional dependencies and damage effects observed in testing. The validated numerical framework was then applied to investigate damage effects on soil-geogrid interaction using a footing configuration, demonstrating that damage type and location significantly influence load-settlement response and soil-reinforcement mechanisms. Soil strain field analysis revealed that damage primarily affects performance by altering load distribution into the foundation soil, with interrupted continuity leading to narrowed stress transmission pathways and reduced load-bearing efficiency. The developed methodology provides a quantitative basis for damage assessment in geogrids and demonstrates the advantages of combining experimental full-field measurements with numerical modelling for understanding complex geosynthetic behavior.