Record details

    The anisotropy of ultrasonic waves velocity and attenuation of migmatite samples under uniaxial loading
    Lokajíček, Tomáš
    Petružálek, Matěj
    Svitek, Tomáš
    US Rock Mechanics/Geomechanics Symposium (47. : 23.06.2013-26.06.2013 : San Francisco, Spojené státy americké)
Publication type
    konferenční příspěvek (zahraniční konference)
Source title - monograph
    47th US Rock Mechanics/Geomechanics Symposium 2013
    S. 1281-1290
    Rozsah: 10 s. : P
Subject category
    brittle failures
    minimum velocities
    rock structures
    stress strain state
    ultrasonic sounding
    uni-axial loading
    velocity anisotropy
    Velocity changes
Abstract (in english)
   A method of velocity anisotropy analysis based on conventional ultrasonic transmission technique is presented. Multiple transducers were used to ultrasonic sounding and monitoring of acoustic emission. A sparse network of transducers located on the rock core surface allows approximation of elastic waves velocity distribution as an ellipsoidal surface. The shape and orientation of velocity ellipsoid is a measure of velocity anisotropy. A study of changes in velocity anisotropy and attenuation was performed on uniaxially loaded migmatite samples with distinct foliation. The cylindrical migmatite samples had a horizontal foliation and one of them had a pre-existed crack. The ultrasonic measurement was carried out during applying a uniaxial constant strain-rate loading. Orientation of the velocity ellipsoid corresponded to the anisotropy of rock structure up to activation of a failure plane.
   Prior to brittle failure, the axis of minimum velocity rotated from its initial direction normal to the foliation to a direction normal to the failure plane, which was determined from location of AE events . The changes in attenuation, induced by uniaxial loading, corresponded to the velocity changes and shown higher sensitivity to the actual stress-strain state of rock samples.
    AV ČR Brno, Geologický ústav
Contributor code
    AV ČR, GLÚ
Source format
Import date
    23. 10. 2014