Seminar: Assessment of fracture toughness in rock using a new pseudo-compact tension (pCT) test and acoustic emission

Abstract: Fracture toughness quantifies the ability of a material to resist the stresses conducting to the propagation and growth of pre-existing cracks or flaws. Fracture generation may occur in three different modes although the most commonly encountered in the so-called mode-I. Developing appropriate testing methods for measuring mode-I fracture toughness (KIC) has attracted a significant interest in the last years. Worth mentioning among them are the recommendations issued by the International Society for Rock Mechanics (ISRM). However, all these methods are difficult to apply on a routine basis due to a number of questions: a) the complexity of sample preparation; b) the amount of material needed; c) the indirect generation of tensile loads via sample compression; and d) the fast crack propagation velocity after peak strength. In this study, we present an alternative approach, called pseudo-Compact Tension (pCT), to measure KIC in rocks using disc-shaped specimens loaded in pure tension. Experiments are further complemented by the concurrent monitoring of acoustic emissions. Our results show that the pCT method is convenient for the assessment of KIC of both fragile and ductile rocks. The method also offers good control even beyond the maximum load, making it possible to study the post-peak behaviour.

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Bio: Andrea Muñoz Ibáñez is a PhD candidate in Civil Engineering at the University of A Coruña (Spain). Since 2014 she has been a research assistant at the Rock Mechanics Laboratory of this University, and she has been engaged in a number of projects for the oil industry. Since 2016 she is developing her doctoral dissertation on the area of fracture mechanics with the aim of establishing a new method for determining mode-I fracture toughness. In 2018 she was a visiting scholar at the National Oceanography Centre (Southampton, UK), and currently she is doing a research stay at Colorado School of Mines (Golden, USA). She has participated in the 4th (Trondheim, 2017) and 5th (Hong Kong, 2019) International Workshops on Rock Physics, where she received two honor awards for her presentations.