Abstract

Acoustic emission based monitoring methods are widely used in non destructive testing. Especially in rock mechanics the acoustic emission contains a Kaiser effect concept which means that reloaded rock emits no acoustic signals until previous stress level is exceeded. This observation probably makes possible to estimate in situ stress state of bedrock. The known basic idea of the method is to measure Kaiser points from rock cores in six independent directions and calculate the complete stress tensor components from these stress values. Before the calculation procedure the local sample directions have to be rotated to global system with rotation matrices. Stress state is evaluated from one site which contains also hydraulic fracturing reference data. The performed tests show that the Kaiser point interpretation is one essential step in the calculation procedure..

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