Experimental investigation of acoustic emissions and their moment tensors in rock during failure

0430243 - GFÚ 2015 RIV GB eng J - Journal Article
Aker, E. - Kühn, D. - Vavryčuk, Václav - Soldal, M. - Oye, V.
Experimental investigation of acoustic emissions and their moment tensors in rock during failure.
International Journal of Rock Mechanics and Mining Sciences. Roč. 70, September (2014), s. 286-295. ISSN 1365-1609. E-ISSN 1873-4545
R&D Projects: GA ČR(CZ) GAP210/12/1491
EU Projects: European Commission(XE) 230669 - AIM
Institutional support: RVO:67985530
Keywords : acoustic emissions * focal mechanisms * moment tensors * rock fracturing * hoop stresses * laboratory experiment
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 1.686, year: 2014

We study acoustic emissions (AEs) associated with shear and tensile failures around a horizontal borehole in a sandstone sample subjected to triaxial stress. The aim is to relate the AE event rate to macroscopic observations of sample deformation and the percentage of isotropic and deviatoric components of the seismic moment tensors to the expected failure mechanisms. The horizontal hole interferes with the applied load and forms a strongly spatially dependent anisotropic stress fi eld, focusing the crack initiation into both shear and tensile failures. The recorded AEs follows reasonably well existing damage models, but the elastic solution of hoop stress does not represent the onset of failure around the borehole. The focal mechanisms correlate with the orientation of macroscopic fractures in the sample. Events close to the borehole show a higher fraction of isotropic percentage in moment tensors compared to events occurring in the macroscopic fracture featuring higher double-couple percentages.
Permanent Link: http://hdl.handle.net/11104/0235136