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Investigation of the Stress-induced Microcracking Processes in Crystalline Rocks through Simultaneous Acoustic Emission and Strain Monitoring
  • Sana Zafar,
  • Ahmadreza Hedayat,
  • Omid Moradian
Sana Zafar
Colorado School of Mines

Corresponding Author:sanazafar@mymail.mines.edu

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Ahmadreza Hedayat
Colorado School of Mines
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Omid Moradian
ETH Z├╝rich
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Abstract

We performed laboratory-scale experiments on Barre granite specimen with a single pre-existing flaw to study the microscopic processes that occur during the deformation of a brittle material such as granite at different stress levels from crack initiation to the failure of the specimen. Here, we focus on the evolution of the tensile and shear cracks as a function of stress under unconfined compression. Acoustic emission technique (AET) in combination with the two dimensional (2-D) digital image correlation (DIC) technique have been used to track the changes in the source mechanisms of the registered AE events, along with the development of strains around the flaw tips of a uniaxially loaded prismatic Barre granite specimen. The parametric analysis along with the moment tensor inversion of the AE signals were used to discuss the cracking levels and the cracking mechanisms. In particular, the microcracks observed through AE monitoring prior to specimen failure were presented in terms of their spatio-temporal evolution and linked with the changes in the inelastic strain component measured through the 2D-DIC along the localized area. The mode of deformation computed from the image based strain profiles, enabled direct comparison of the nucleation, growth and interaction of the microcracks with the AE monitoring technique.