A new calculation model of blasting damage degree-Based on fractal and tie rod damage theory

Based on blasting engineering experience, the damage degree model of a blasting pressure relief zone is constructed. The energy conservation principle is applied in the blasting pulverization zone. The shock wave energy formed via the explosion is divided into surface energy of rock fragmentation and strain energy inside the rock. Consequently, the prediction model of rock fragmentation particle size in the blasting area was established using rock fracture theory. Also, using the rock fragmentation particle size model combined with fractal theory, a calculation method of fractal dimension related to broken rock particle blockiness was proposed. The correspondence between fractal dimension and blast damage degree was established, and the damage degree of the blasting crushing zone was determined. The rock rupture in the blasting rupture zone is along the direction of the initial weak damage, and the damage model of the fracture zone is analyzed using a weak-face parallel bar damage model. Then, the LS-DYNA numerical software and engineering practice are used to fit the theoretical calculation results. The results show that the fits of the two models reach 95% and 94%, respectively, and these results verify the model applicability, providing a new method for studying the evolution law of rock blasting damage.