Abstract
Creep tests are commonly performed to characterize time-dependent deformation of geological materials. Classical measuring methods are not suitable for long term tests and not able to provide full three-dimensional strain fields. In this study, Digital Volume Correlation (DVC) is applied to X-ray micro-tomography (XRMT) images from creep tests on a hard clayey rock. In situ uniaxial compression creep tests are performed under different levels of stress and with different loading orientations with respect to the structural anisotropy of rock. Based on the XRMT images taken during the creep tests, DVC is applied to compute the full three dimensional strain fields and global averages strains of tested samples. The effects of bedding planes and hard inclusions on the non-uniform distribution of strains are analyzed.
Highlights
Creep deformation is commonly observed in geological materials, in particular in clayey rocks.Description of time-dependent behavior of these materials is an essential issue for long-term stability analysis of related structures
The application of digital volume correlation to X-ray images provides an efficient method for the characterization of full strain field in heterogeneous rocks during long term creep tests
This method can be extended to complex environmental conditions with variations of temperature and moisture content
Summary
Creep deformation is commonly observed in geological materials, in particular in clayey rocks. We shall apply the combination of DVC and X-ray micro-tomography to investigate creep deformation of the Callovo-Oxfordian (COx) claystone. This clayey rock is selected as a potential geological barrier for underground disposal of radioactive waste in France. Few studies have so far been devoted to the characterization of non-uniform local strain fields during creep tests in the COx claystone. X-ray micro-tomographic images are taken during each creep tests Based on these images, non-uniform local strains fields and global averaged strains of tested samples are calculated by using. The effects of materials anisotropy on the creep deformation are analyzed
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