Modification and validation of cracked zone range under coupled in-situ stress and blasting load.

Exploring the characteristics of blasting crack propagation under the action of in-situ stress is of great significance for guiding the layout of blast holes on site. This paper proposed a modified calculation method for the range of crushed zone and cracked zone under the action of in-situ stress based on the coupled stress distribution characteristics of in-situ stress and blasting load. A numerical simulation model for single hole blasting was established based on the Holmquist-Johnson-Cook (HJC) model, and the modified method was validated. Meanwhile, the influence of burial depth and lateral pressure coefficient on crack propagation characteristics was analyzed, and the effects of axial loading coefficient, lateral pressure coefficient, dynamic compressive strength, and dynamic tensile strength on the range of crushed zone and cracked zone were studied. It is concluded that the modified theoretical calculation method predicts the crack extension length and direction with high accuracy, and the errors with the numerical simulation results are controlled at 5.5% and 4°, respectively. Under the action of coupled stress field, the crack length in various directions of the blasthole show non-uniform distribution, and the tangent value of the angle between the longest radial main crack and the vertical direction and the lateral pressure coefficient are basically the same. The research results can provide reference for the design of deep rock blasting parameters and the improvement of explosive utilization efficiency.