State-of-the-art damage assessment methods for brittle rock using digital image correlation and infrared thermography

Abstract

The microstructures of rocks are affected by mechanical loading causing damage in the rock leading to failure. Therefore, understanding the damage evolution in rock is of great significance to stability of rock engineering structures. For the damage evolution process the state-of-the-art Digital Image Correlation (DIC) and Infrared Thermography (IRT) systems were used. Complimentary measurements integrating the use of strain gauge and Acoustic Emission (AE) were also performed. Series of indirect tensile strength (Brazilian) tests were conducted for the damage evolution. DIC and IRT provide high resolution strain mapping across the surface of Brazilian discs throughout the test. Based on acoustic emission, full field stress-strain characteristics, and temperature change, damage evolution for brittle rock were analysed. Experimental results showed that the non-contact technique DIC and IRT have major advantages as an auxiliary to the conventional external strain measurements. DIC can be used as a better technique for not only tracing the full-field deformation behaviour but also strain localisation. IRT was also found to be effective method for detecting failure process. However, since quasi-static loading cause dissipation of heat quickly, IRT can be more effective for high strain rate loading cases.