Abstract
We propose a novel method for studying the λ/μ ratio, the vP/vS ratio and Poisson's ratio of rocks based on the determination of highly accurate moment tensors of acoustic emissions (AEs). The validity of the method is verified on observations of 539 AEs recorded in a sandstone sample during a semi-circular bend test. We show that the sandstone exhibits the so-called bi-modular behaviour indicating that rock parameters significantly differ under compressive and tensile stress regimes. In addition, the zone characterized by highly tensile fractures is auxetic. For increasing shear component in AEs, Poisson's ratio increases and the auxetic effects disappear. The proposed approach for determining the λ/μ, vP/vS, and Poisson's ratios using AEs is fully independent of standard techniques based on measuring deformation of rock samples. The approach might find applications in detailed studies of rock behaviour under various stress conditions, in particular, in assessing the bi-modularity of rocks measured during a single experiment.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
