Abstract
A 3D numerical model was presented to investigate the blast-induced damage characteristics of highly stressed rock mass. The RHT (Riedel, Hiermaier, and Thoma) model in LS-DYNA was used to simulate the blast-induced damage and its parameters were calibrated by a physical model test. Based on the calibrated numerical model, the influences of confining pressure and free surface span on the blast-induced damage characteristics were investigated. The results show that under uniaxial loading, the crater volume increases with confining pressure increases. The uniaxial static load can change the optimal burden and the critical embedding depth of charge. In stressed rock, the variation law of the crater shape affected by radial tensile fractures is opposite to that affected by reflected tensile fractures. Under the biaxial static load, the crater volume of the borehole placed on the side of the max static load is greater than the other side. The explosion crater can be improved by increasing the free surface span on the same side. Finally, it is suggested that the blasting efficiency can be improved by preferentially detonating the charge on the side of the max static load, and then the charge on the other side can be detonated with a wider free surface span.
Highlights
With the increase of excavation depth, the in situ stress increases gradually and plays an increasingly important role in the rock breaking by blasting
In order to determine the parameters of borehole layout and blasting parameters in highly stressed rock mass as well as for safe and efficient production, it is necessary to investigate the blast-induced damage characteristics in the static-dynamic stress field
The outcomes showed that the crater shape becomes oval with the long axis aligned on the loading direction, and the open angle in this direction and the crater volume is greater with the increase of confining pressure under uniaxial static load
Summary
With the increase of excavation depth, the in situ stress increases gradually and plays an increasingly important role in the rock breaking by blasting. Hu and Lu [8,9] studied the formation and propagation of crack induced by presplitting blasting in highly stressed rock mass via a mathematical model and concluded that the in situ stress can restrain the development of cracks between the presplitting holes when the in situ stress is perpendicular to the crack face Yang and He [10,11] experimentally investigated the influence of confining pressure and ratios of horizontal-to-vertical pressure on the blast-induced rock fracture. Jayasinghe, Ma and Li [15,16,17,18] used LS-DYNA to investigate the influence of in situ stress on the blast-induced cracks Their results showed that the crack propagation trends towards the direction of maximum compressive pressure. Based on the tested mechanical parameter, the following sections obtain the other material parameters through empirical formulas or related literatures
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