A Volumetric Strain-Based Method to Determine Crack Initiation Stress of Low-Porosity Rocks

Crack initiation stress is one of the key parameters of rocks. Reasonable determination of this stress threshold is important for describing mechanical properties. Previously proposed methods are strongly influenced by user´s judgment. A new method based on volumetric strain is proposed to establish crack initiation stress of low-porosity rocks during rock failure. Compression tests on granodiorite samples have been conducted to obtain stress-strain relationships. According to comparison of crack initiation stress values obtained from different methods, the effectiveness of the proposed objective method is verified.