Strains, elastic-wave velocities, and acoustic emissions during the creep of granitic rocks.

摘要

A series of creep experiments of granitic rockswere carried out under the confining pressure of 50 MPa . Timeto failure depends longarithmically on the stress level applied.Creep curves show three stages of typical creep deformation; theprimary creep, the secondary creep and the tertiary creep. Tine toonset of the tertiary creep normalized to the failure time has norelationship with the stress level. Elastic-wave velocities decreaseafter the onset of tertiary creep. Based on the calculation usingthe data of elastic-wave velocities and dilatant strains, aspectrations of cracks increase during the creep. Activities of acousticemission (AE) increase prior to the failure. Time to onset ofincrease of AE activity normalized to the failure time is longer asthe stress level decreases.