Electronic Speckle Pattern Interferometry in Characterizing Rock Fracture

Abstract

The fracture of rock and concrete is characterized by the formation and propagation of the fracture process zone. It has been suggested that this process zone is initially formed by micro-cracks which subsequently coalesce into a discrete macrocrack. Quantitative study of discrete crack propagation has become an important issue in rock mechanics. Examples of application of this research area include: rock blasting, oil drilling, and more recently, in storage of nuclear wastes in underground rock salt deposits. Linear Elastic Fracture Mechanics (LEFM) has been applied by several researchers to understand crack propagation in rocks, but the success of the LEFM approach has been limited due to the presence of a FPZ at the crack tip, and nonlinear behavior of the material is known to be a consequence of this zone. This nonlinear behavior has significant effect on the propagation of the fracture and consequent mechanical behavior. There is a lack of detailed information regarding the crack propagation as well the FPZ, including shape, size, traction zone and crack width. In order to better understand the fracture mechanics of rock, following issues need to be addressed, i.e. detection and quantification of the FPZ through experiment, interpretation of experimental data to obtain valid material models and use of such models in the analysis of a great many engineering problems that involve geotechnical structures.KeywordsStress Intensity FactorCrack Opening DisplacementStress Intensity FactorLinear Elastic Fracture MechanicFringe PatternThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.