Influence of Confining Pressure on the Kaiser Effect in Post-Failure Region Using OYA-Tuff
Hidehiko WATANABE
Abstract:In order to clarify the influence of confining pressure on the Kaiser effect in post-failure region, acoustic emission (AE) experiments were performed under triaxial loading conditions using Oya-tuff. Triaxial compressive pre-loading was performed until post-failure region, and then re-loading test was performed under different confining pressure. The rapidly increasing point of cumulative AE event count was determined as the peak point of AE event count rate increment. The estimated stress was compared with pre-stress. The main results are summarized as follows. (1)In the case of the re-loading test performed under the same confining condition, the remarkable AE increase appeared at the differential stress level at the previous residual strength. (2)In the case of the re-loading test under the lower re-confining pressure than the pre-loading test, the estimated stress is smaller than differential stress at previous residual strength. (3)In the case of the re-loading test under higher confining pressure, the estimated stress was equivalent to the differential stress at the previous stress peak. Key Words:Kaiser effect, Acoustic emission, Triaxial compressive test, Confining pressure, Post-failure region