Localization by Acoustic Emission in Transversely Isotropic Slate

Abstract

A method for localization by acoustic emission in transversely isotropic media is developed and validated. Velocities are experimentally measured and then used to calculate a database of theoretical arrival times for a large number of positions. During an actual test, positions are assigned by comparing measured arrival times with the database's arrival times. The method is applied during load tests on slate samples and compared with visual observations of fractures. The localization method allowed for a good identification of the regions of fracturing at different stages during the test.

Experimental observation of fracture patterns in layered slate

“…The exact set-up and method of calculation is described by Debecker and Vervoort (2009b). Figure 10 presents the different stages of fracture growth that are visually observed, referred to by the same numbers, together with the positions of the localized acoustic events, for sample C2.…”

“…An additional difficulty with slate, is that the wave velocity in slate is not isotropic, but direction dependent. The different velocities are experimentally measured and a program is written in Matlab to perform localization (Debecker and Vervoort 2009b).…”