Research on the damage characteristics of rock masses based on double guide-hole blasting under high in-situ stress

In complex high in-situ stress conditions, how to achieve the ideal rock blasting effect through effective methods is often a difficult point of blasting operations. This paper analyzes the influence of guide holes on blasting effect by adding guide holes to the rock pre-treatment method. Based on the particle expansion method to carry out double-hole blasting experiments, the influence of the blasthole spacing and ground stress on the blasting effect is investigated from the levels of macroscopic cracking effect, microscopic particle contact and so on. The study shows that: (i) the setting of empty holes between the gun holes can enhance the crack penetration effect, and the penetration effect is more obvious when the distance between the gun holes and the empty holes is less than 2.5 times the radius of the crushed zone. (ii) At the level of contact force chain, when the distance between blastholes and empty holes is less than 2.5 times the radius of the crushing zone. The compressive stress in the direction perpendicular to the direction of the blasthole line inhibits crack development, and the tensile stress in the direction parallel to the blasthole line promotes crack development. The main stress direction is perpendicular to the direction of the blasthole line. (iii) As the distance between the blastholes increases, the effect of crack suppression by stresses in the vertical direction decreases, and the main force direction is parallel to the direction of the blasthole line.