Tohru Abe

Theoretical Study of Time-Dependent Strength of Granite Based on Micro-Structure Model.

In this study, time-dependent strength of granite was interpreted in terms of micro-structure model.Using Kemenys model, strength realized in monotonic loading test, creep test and cyclic loading test under uniaxial compressive condition was calculated and compared with the experimental results. In this model, the rock is assumed an elastic medium containing a column of sliding cracks and the cracks grow due to stress corrosion. It was confirmed that this model is able to precisely represent the effect of loading rate on compressive strength and the creep strength. However concerning on the fatigue behaviors, time to failure was overestimated when stress amplitude became large.Therefore, we have modified Kemenys model, where the coefficient of friction of sliding cracks was reduced gradually under cyclic loading. It was found that this modified model was able to explain the effect of stress amplitude and maximum stress, quantitatively. It was also found that the effect of loading frequency on the fatige strength was similar between the prediction and experiment.