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The role of S-wawe velocities in determining the elastic anisotropy of rocks: number modelling and lab measurement
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SYSNO ASEP 0444549 Druh ASEP C - Konferenční příspěvek (mezinárodní konf.) Zařazení RIV D - Článek ve sborníku Název The role of S-wawe velocities in determining the elastic anisotropy of rocks: number modelling and lab measurement Tvůrce(i) Svitek, Tomáš (GLU-S) SAI, RID
Lokajíček, Tomáš (GLU-S) RID, SAI, ORCID
Petružálek, Matěj (GLU-S) RID, SAI, ORCID
Vavryčuk, Václav (GFU-E) ORCID, RIDZdroj.dok. Innovations in Applied and Theoretical Rock Mechanics. - Montréal : Canadian Institute of Mining, Metallurgy and Petroleum, 2015 - ISBN 978-1-926872-25-4 Poč.str. 18 s. Forma vydání Tištěná - P Akce International Congress of Rock Mechanics /13./ Datum konání 10.05.2015-13.05.2015 Místo konání Montréal Země CA - Kanada Typ akce WRD Jazyk dok. eng - angličtina Země vyd. CA - Kanada Klíč. slova acoustic properties ; body waves ; geomechanics ; microstructures ; seismic anisotropy ; wawe propagation Vědní obor RIV DC - Seismologie, vulkanologie a struktura Země CEP LH13102 GA MŠMT - Ministerstvo školství, mládeže a tělovýchovy GAP104/12/0915 GA ČR - Grantová agentura ČR GAP210/12/1491 GA ČR - Grantová agentura ČR GA13-13967S GA ČR - Grantová agentura ČR Institucionální podpora GLU-S - RVO:67985831 ; GFU-E - RVO:67985530 Anotace The most common type of waves used for probing anisotropy of rocks in laboratory is the direct P wave. Information potential of the measured P-wave velocity, however, is limited. In rocks displaying weak triclinic anisotropy, the P-wave velocity depends just on 15 linear combinations of 21 elastic parameters, called the weak-anisotropy parameters. In strong triclinic anisotropy, the P-wave velocity depends on the whole set of 21 elastic parameters, but inversion for 6 of them is ill-conditioned and these parameters are retrieved with a low accuracy. Therefore, in order to retrieve the complete elastic tensor accurately, velocities of S waves must also be measured and inverted. For this purpose, we developed a lab facility which allows the P- and S-wave ultrasonic sounding of spherical rock samples in 132 directions distributes regularly over the sphere. The velocities are measured using a pair of P-wave sensors with the transmitter and receiver polarized along the radial direction and using two pairs of S-wave sensors with the transmitter and receiver polarized tangentially to the spherical sample in mutually perpendicular directions. We present an inversion method for elastic parameters describing general triclinic anisotropy. We demonstrate on synthetic tests that the inversion becomes more robust and stable if the S-wave velocities are included. This applies even to the case when the velocity of the S waves is measured in a limited number of directions and with a significantly lower accuracy than that of the P wave. Finally, we analyze velocities measured on a rock sample from the Outokumpu deep drill hole, Finland, including the error analysis for several levels of confining pressure. Pracoviště Geologický ústav Kontakt Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Rok sběru 2016
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