Numerical simulation of influence of filled joint on the crack formed by notch hole blast

Abstract

Field practice shows that, joints have very adverse influence on crack formation in the protective layer of rock mass, during blasting excavation. To improve the crack formation in rock mass with filled joints, V-shaped notch blasting method is conducted in simulation and site. It can be seen from the calculation in dynamic finite element method that the V-shaped notch boreholes played a certain role of guiding energy in rock blasting excavation, the crack is generated along the hole attachment when the radial decoupling charging coefficient is .198. Studies show that, when a layer of filled joint is at the middle point of the attachment of notch borehole, the compressive stress at the middle point of filled joint will increase as the angle between the joint and the borehole attachment increases. When the angle is 15°, the damage depth of surrounding rock, d ≈ 3R; the angle is 30°and 45°, d > R; the angle is 60°, 75°and 90°, d ≤ R, the penetration crack between adjacent boreholes can be formed along the borehole attachment.