Introduction to the Theories of Rock Fracturing

This chapter provides the basic theories and principles behind rock fracturing and rock fracture mechanics. It starts with introducing the Griffith flaws and energy balance theory, which is the foundation of the modern fracture mechanics. Then the concept of stress intensity factor for linear elastic fracture mechanics is introduced, followed by a description of the criteria for fracture propagation. Also described is the subcritical crack growth which dominates the time dependent long term stability of fractured rock. The experience shows that rocks under static load level may be stable, while at the same cyclic load level failure is observed. A short introduction to theories and factors related to cyclic fatigue behavior of rocks is presented in the end of the chapter.