Optimization of the digital image correlation method for deformation measurement of geomaterials

For the application of the digital image correlation (DIC) method in the deformation measurement of geomaterials, the conventional approaches can hardly realize optimized results in terms of precision and speed, especially for geotechnical tests with variable scales and going through discontinuities. Considering the deformation characteristics of geomaterials, two algorithmic approaches were proposed to deal with the conundrums in the application of DIC for experimental measurement. Incorporated with DIC and the acoustic emission system, uniaxial compression tests were performed on rock-like materials to investigate the effectiveness of the proposed methods. Based on preliminary trials through the adjustment of conventional DIC parameters, it is hard to reach an accurate result for materials with obserable cracks. The proposed algorithm shows an optimized revision for subsets in regions subject to discontinuity influence whose efficiency is independent of the crack size. Meanwhile, the fast-speed algorithm designed for DIC enables the searching scope auto-adjusted, and the computation time can be reduced to approximately one-tenth of the conventional one. The proposed algorithm was implemented in the self-developed DIC software, implemented program, which is specially designed for geotechnical tests.