クラスII岩石の周圧下の挙動の載荷速度依存性

抄録

A recently developed testing method which takes a linear combination of axial stress and strain as control variable was applied to investigate the post-failure behavior of rock under various confining pressures up to 40MPa. Though the method was only applied to uniaxial compression test in the previous studies, this study showed that it is also applicable to triaxial compression test, and the following results were obtained:
Firstly two out of the four rocks showed transition from class II to class I characteristics as the confining pressure is increased. And after the transition, a rapid decline in load bearing capacity was found to become gradually less remarkable as the confining pressure is further increased.
For tested rocks except Akiyoshi marble, when the loading rate was raised by 10-fold, the compressive strength increased by nearly same quantity no matter how much the confining pressure was. The compressive strength of Akiyoshi marble did not always increase when the loading rate was increased. Such behavior may be related to the mechanical property of calcite crystal, which is remained to be further investigated.