き裂進展開始破壊靭性を有する花こう岩の引張軟化曲線の決定と破壊評価に関する研究

抄録

The tension-softening model has been employed to evaluate the crack growth behavior in rocks. In this paper, the tension-softening relation was determined taking the crack tip toughness into account. The extended J-based technique is applied to determine the tension-softening curve for a granite which has crack tip toughness. Compact tension (CT) specimens were used to conduct J-based fracture toughness tests on the granite. The crack tip toughness was measured using K-resistance curves in the granite. Three sizes of CT specimen were used to examine the specimen size effect on the deduced tension-softening curves. It was shown that the extended J-based technique provides reasonable tension-softening curves irrespective of the specimen size, suggesting the validity of the extended J-based technique. Finally, the necessity of the introduction of the crack tip toughness is demonstrated by performing numerical simulations of the load-displacement behaviors of the granite.