4D imaging of a porous carbonate rock under triaxial loading: quantitative correlation between local porosity and...

The study of the mechanical behaviour of carbonate rocks has benefited from the evolution of experimental tools, due to their complex multi-scale microstructure. Triaxial cells transparent to X-rays have emerged and allowed in situ investigation of progressive failure developments and their link with microstructure. We conducted a series of 4D X-ray computed tomography mechanical tests on porous Saint-Maximin limestone at the PSICHE beamline of Synchrotron SOLEIL. Tests were performed using an in-house-developed triaxial press, Modulo. Volumes were scanned using a helical acquisition and reconstructed at 2.83 µm. They were then analysed using digital volume correlation. Volumetric strain and shear strain magnitude maps were computed using a 100 voxels gauge length with Paraview. Additionally, we computed porosity maps based on mean grey levels, at the same gauge length. Analysis of total and normalized incremental strain maps was carried out. We also compared volumetric strain maps with the initial porosity maps. Each step of the procedure is described herein. The errors on strain and porosity are discussed.