Extending Digital Image Correlation to Reconstruct Displacement and Strain Fields around Discontinuities in Geomechanical Structures under Deformation

Reconstruction of displacement and strain fields in geomechanical structures from surface images is a challenging task. Digital Image Correlation (DIC) is a well known technique to achieve these tasks if deformation is continuous but it fails in the presence of discontinuities. This paper investigates the application of the DIC technique to displacement and strain field reconstruction in the presence of discontinuities, and presents a post-processing algorithm that leverages the convergence results in DIC to reconstruct displacement and strain fields around discontinuities with high accuracy. The proposed algorithm uses the results obtained from DIC and concentrates on the area where DIC fails. Pattern matching is conducted on the area around the discontinuities and associated displacement is found for each pixel. The proposed algorithm is tested using two different discontinuity scenarios: dislocation and fracture in structures. The results show that the proposed algorithm successfully reconstructs the displacement and strain fields to sub pixel accuracy of 1/10th of a pixel.