Research Article

An Evaluation Method of Rock Brittleness Based on the Prepeak Crack Initiation and Postpeak Stress Drop Characteristics

Table 4

Classification and description of brittleness index B1.

GradeB1Description

11M⟶−∞, ideal brittleness
20.6321∼1−∞ < M < − E, high brittleness
30.6321M = − E
40∼0.6321E < M < 0, low brittleness
50M = 0, ideal plasticity
6<0M > 0, strain hardening