The influence of stiffness of the true triaxial testing machine on the rupturing and acoustic emission of rocks and its correlation with seismic activities

This paper introduces how the ratioR of the characteristic stiffness of rock samplevs. the stiffness of testing machines would influence the rupturing process and the acoustic emission (AE) on the part of the tested rock samples. Result of the experiment shows: WhenR>0.20, the rock sample would rupture abruptly; whereas whenR<0.20, the rock samples would rupture slowly. When the samples rupture abruptly, the time-dependent variation of the AE rate takes such a pattern:peak value—stable low values—rises to the maximum value (concentration)—drops back to the minimum value (quiescence)—(rises again)—ruptures. Moreover, smallerR-value tends to be associated with longer quiescence and vice versa. WhenR>1.50, no pre-failure quiescence is detected. When the rock samples rupture slowly, the variation pattern of the AE rate (after the stress has increased to more than 50% of the rupturing stress) is as the following:stable low (or high) values—rises (or drops) to its maximum (or minimum) values and then continues for some time—ruptures. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 223–233, 1991. This study is supported by the Chinese Joint Seismological Science Foundation.