Acoustic Emission from Fracturing of Rock Samples under Quasistatic Effects
V. I. Vostrikov
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Rock samples, loading, Brazilian method, deformation, spectrum, thermal field, fracturing, energy
Abstract
Experimental fracturing is carried out in rock samples of different strength, taken in the same borehole but at different depths. From the analysis of acoustic emission from fracturing of the rock samples under quasistatic loading, the spectral composition of acoustic emission signals is determined in the samples in elastic, plastic and soft straining before failure. Microcracks initiated in early loading generate high-frequency signals. As loading is increased, the spectrum expands toward lower frequencies with opening of existing cracks and initiation of new cracks. The values of the energy release intensity during acoustic emission in samples under quasistatic loading up to failure are given. The introduction of the specific energy release coefficient of acoustic emission in fracturing of the test samples enables ranking the samples by their mechanical properties. The thermal fields mapped on one of the test samples under varied quasistatic loading allow judging on the behavior of the internal stresses in the sample.
|
