Soil Crack Testing with DIC
Abstract
Clay fine soils are characterized by an ability to change volume when subjected to suction. Soil cracking due to desiccation is a phenomenon of great importance in the environmental geotechnical engineering domain. Aiming to understand the shrinkage mechanism, and conditions that lead to the appearance of drying cracks, new experimental testing coupled device digital image correlation‐ clay ring test (DIC‐CRT) was developed to investigate fine soils shrinkage and cracking. The new feature of this paper is to link both measurement techniques, based on 2D/3D‐DIC and an innovative CRT, in order to assess stress and strain in soils during desiccation. Tests were carried out on kaolinite having a liquid limit of wL = 40% and prepared as a slurry with w = 1.5 wL of water content. The results highlight the relevance of combining these two techniques, particularly to assess internal stresses developed in the material using CRT and link them to strains leading to cracking measured by the DIC method.
Although DIC is not designed to measure crack growth and openings, when used carefully, some measurements can be obtained by comparing the pixel shift around the crack. The strain value computed over the cracks is not typically used for anything other than identifying the location of the cracks. The displacement at arbitrary locations along the crack can be measured using VIC-3D’s virtual extensometer inspector tool.
