DIGITAL IMAGE CORRELATION PROCEDURE TO CHARACTERIZE SOIL SURFACE-LAYER CRACKING

This study was conducted to characterize surface layer cracking in Ver tisols by determining surface displacement trends. A disturbed sample from the Ap horizon of a Randall clay (fine, smectitic, thermic Ustic Epiaquerts) was evaluated. Digital image correlation (DIC) was used to track the movement of points on the surface as the soil dried and to assess the development of soil surface cracking, Displacement fields a mong a group of images were obtained by using a crosscorrelation algor ithm. The displacement vectors resulting from the analysis of the disp laced fields can be used to show cracking patterns on a ground-up soil sample from a Vertisol before they become visually apparent. Digital image correlation may be used to calculate the deformation of the surf ace layer with relatively high precision.