To study the relationship between brittleness index and elastic strain energy

the lateral strain response method was used to determine the crack initiation stress of hard rock. By using the crack initiation stress and peak stress of rock

the relationship between brittleness index and elastic strain energy was explained based on fracture mechanics theory and energy theory

and a functional relationships were constructed between brittleness index and elastic strain energy from uniaxial compression test for two types of rock. Results show that the brittleness indexes B13

B14are in power function relationship with the crack initiation elastic strain energy (single variable)

and the brittleness indexes B15

B16are in power or linear function relationships with the crack initiation elastic strain energy (single variable). However

no apparent functional relationship was discovered between the brittleness indexes B13

B14

B15

B16and the peak elastic strain energy (single variable). The new brittleness index could be either obtained from both the crack initiation strain energy and the peak elastic strain energy (two variables)

or the crack initiation elastic strain energy (single variable). The relationship between brittleness index and the peak elastic strain energy is of great significance for studying rock burst proneness. The calculation method for brittleness index was redefined. Besides

the verifications of two examples show that this method

using the crack initiation elastic strain energy

demonstrates certain credibility. This study provides a new method determining the relationship between brittleness index and the crack initiation elastic strain energy of rock.