Abstract: The disturbance and damage induced by excavation and blasting, especial blasting cumulative damage effects resulted from frequent blasting, will play down the integrity of rock mass, weaken the mechanical parameters of rock mass and threaten the stability of rock engineering surely. Considered the blasting cumulative damage effects of rock mass, the shortages of Hoek-Brown criterion and its modified expressions were pointed out. The methods of obtaining the value of and s which could reflect the blasting cumulative damage effects, blasting disturbed state and the lowering degree of its mechanical parameters, were found by introducing integrity coefficient and damage factor D. The cumulative expanded models of rock mass blasting damage were found with the baseline of rock mass sound velocity reducing ratio and the models were used in the amended expressions of Hoek-Brown criterion, based on the relationship between sound velocity variation and blasting cumulative damage effects. The analysis of the amended expressions was carried out based on the simulative blasting tests in-situ and the data of sonic measurement. The research results show that the amended expressions of Hoek-Brown criterion taken blasting cumulative damage effects of rock mass into account are reasonable.

Key words: rock mechanics, blasting cumulative damage effects, mechanical parameters of rock mass, Hoek-Brown criterion, amended expressions