Mechanical properties and Acoustic Emission response of carbonate fault breccias, a study from Greece

Abstract

The present study aims to investigate the mechanical properties and Acoustic Emission (AE) response of carbonate fault rocks in Lefkada Island, Greece. In the aforementioned region, tectonic processes have resulted in the formation of fault breccias with poor mechanical properties and complex behavior. In these weak formations, conventional laboratory testing methods are restricted due to their disintegration during sampling and specimen preparation. A novel sample preparation and laboratory testing technique are used jointly with a back-analysis of a co-seismic landslide, that occurred during a M w 6.5 earthquake in 2015. These two approaches are employed to characterize and predict the mechanical behavior of these formations. The uniaxial compressive strength (UCS) of the fault breccias, determined in the laboratory, has a wide range primarily due to the complex nature of the material. The back-analysis, using a 3D limit equilibrium method, proves that the shear strength of the in-situ material is significantly lower than that determined in the laboratory. Finally, the acoustic emission response of fault breccias was different compared to that of brittle rocks. B-value analysis and the damage variable evolution indicate that the accumulated damage within fault breccias is higher than expected and thus they are more prone to fatigue. Thematic collection: This article is part of the Leading to Innovative Engineering Geology Practices collection available at: https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices