Study on long-term beghavior of weak rock

Okubo, Seisuke*

Using the boring core obtained in the Horonobe region, the data in triaxial compression stress state was acquired, and the examination was carried out on the effect of the confining pressure on long-term deformation or stability of the sample rock. At first, triaxial compression tests were carried out. In the test, loading rate (strain rate) was changed several times to obtain viscoelastic properties of the sample rock. Multi-stage creep tests were also performed in triaxial compression stress. The parameter set of a constitutive equation of variable compliance type was obtained based on the testing results. In this study, a transparent triaxial cell recently developed by this author was used. The external cylinder of this vessel was made of the transparent acrylic resin. Therefore, gradual deformation of the sample under testing was easily and clearly observed.