MMIJ Annual Meeting

To estimate long-term deformation and stability of underground structures, knowledge of the loading rate dependence of rock is essential. In order to understand the effect of water on loading rate dependence, the studies considering wide range of the water effects are necessary. In this study, the effect of water on the loading rate dependence of rock strength was investigated with conducting uniaxial compression tests under the following three conditions: completely-dried, air-dried and water-saturated conditions. The loading rate dependence of rocks was estimated from the results of alternating loading rate tests with four Japanese rocks, in which a rock specimen was compressed under the loading rate alternated between slow and high rates. Also, Inada granite were used to conduct constant strain rate tests. From the experimental results, the degree of the loading rate dependence in water-saturated condition was higher than that in completely-dried and air-dried conditions, and that under completely-died condition was the lowest. The effect of water on the peak strength and Young’s modulus, and the relation between the mechanical characteristics in each condition and the porosity in each rock type was also discussed.