Effect of Discontinuities on Elastic Wave Velocities in High-Stress Rock Samples: Experimental Research Using Ultrasonic Interferometry
P. V. Nikolenko, M. G. Zaitsev
National University of Science and Technology, Moscow, Russia
Keywords: Stress-strain behavior, rocks, ultrasound, coda wave, crack, control
Abstract
The scope of the experimental research embraces velocities of elastic waves in rock samples before and after formation of a horizontal main crack. In undamaged samples, there is no essential change in the elastic wave velocity as the axial pressure increases from 0 to 20 MPa. The main crack having its surfaces approaching gradually leads to the increase in the elastic wave velocity. Aimed to improve sensibility of kinematic ultrasonic parameters relative to mechanical stresses, the coda wave interferometry algorithm is implemented as an analysis of times of the first arrivals of multiply scattered waves. With the mentioned algorithm, sensibility of the ultrasonic control grows considerably even in uniform samples.
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