Spatiotemporal Evolution of Strain and Compaction Localization in Leitha Limsestone: Synchrotron Tomographic Imaging and Digital Volume Correlation

Abstract

AbstractThe HADES rig at the European Synchrotron Radiation Facility allows in situ 3D imaging of the whole rock sample as it is triaxially compressed. The μCT data provide an integrated perspective of the spatiotemporal evolution of damage and strain localization on scales ranging from grain to continuum. An experiment was conducted on Leitha limestone at a confining pressure of 20 MPa. With increasing differential stress, the sample strain hardened in two distinct stages of yielding. The second stage was associated with development of five discrete compaction bands. The μCT data on the voxel-scale delineate in refined details the nucleation and propagation of discrete compaction bands under quasi-static loading, as well as the micromechanical processes. To characterize quantitatively the spatiotemporal evolution of strain, we systematically applied digital volume correlation to this unique set of in situ synchrotron CT data. We have obtained some of the first 3D results on grain-scale heterogeneity of strain in a porous aggregate, which elucidate the mechanics of the bifurcation phenomenon, as well as the fine structures and geometric complexity of compaction bands.KeywordsStrain localizationCompaction bandSynchrotron tomography