Theoretical study of rock for estimating long-term behavior (Contract research)

Ichikawa, Yasuaki*; Choi, J. H.*; Hirano, Toru; Matsui, Hiroya 

On the radioactive waste disposal, the long-term mechanical stability of tunnel was required. Therefore, we have been developing the method evaluating the stability. This report describes the works in the FY2008. Chapter 1 is the overview. In Chapter 2 we performed pressure dissolution experiments using specimens of single crystal quartz, since the dissolution reaction is engaged with a deformation and failure process of polycrystalline rock. After applying stress the surface of contacted area of quartz was observed by microscope and found traces of dissolution and reprecipitation. We managed two types of experiment; a closed solution experiment and a flow-through experiment. We discussed the Si dissolution rate based on the experimental results measured by ICP-AES. Fundamental mechanism of time-dependent creep and stress relaxation for crystalline rocks was discussed in Chapter 3 based on a concept of mechano-chemical coupling phenomena (as treated in Chapter 2) at micro-crack tips.