Estimation of Mode I Fracture Toughness of Rock by Semi-Circular Bend Test under Confining Pressure Condition

It is essential to understand the mode I fracture toughness of rock under in situ conditions found underground, such as confining pressure, for assessment of the stability of underground rock structures. Some researchers have performed several types of fracture toughness tests of rocks under confining pressure condition. However, the ordinary fracture toughness tests do not consider the effect of confining pressure in their estimation equations....