Dynamic Numerical Simulation Of V-shaped Notch Blasting

V-shaped notch blasting is that cutting slots with certain depth along axis -direction of the hole is determined according to the blast-crazing, and then load uncoupled charge and detonation. As with this technology, it not only can make rock fracture smoothly and slightly damages toward both sides of fracture plane, but also has good performance in the control outline surface blasting, such as, blasting on the slope, blasting around the tunnel outline surface, cut-blasting in row stone mining and so on. It is valued to be popularized as control blasting technology. Therefore, it is very important in theoretic and practical engineering to restudy fracturing mechanism of notch blasting with dynamic computerized simulation software, and study the impact on notch parameter and charging parameter changing to fractured control blasting effect.In this paper, the object of research is incising blasting engineering in granite row stone exploitation. In order to analyze the fracturing mechanism principles of V-shaped notch blasting and the influence of blasting parameter changing to V-shaped notch blasting effect, the elastic-plastic isotropy and multi-notched holes of plane strain model are set up, dynamical finite element analysis software ANSYS/LS-DYNA is applied, dynamic stress distribution and its change rule of rock around notched holes and between two holes is calculated, dynamic fracturing mechanism is studied with fracture mechanics theory, and influence of blasting parameter changing to notch blasting effect is discussed. The main research achievements and conclusions are as follows.The dynamic stress distribution surround the slot holes are different from the common round holes. Due to the V-shaped holes, the dynamic stress at the center of the two holes is obviously greater than other places, this theoretically proved that the initial crack occurs at the tips of slot, the line between the two holes is the crack extending direction, and strongly confirmed that notch blasting has more advantages in the effect of boundary control, and tally with the experimentation and practical blasting.Fracturing mechanics is applied to figuring out the dynamic initial-crack critical pressure, propagation critical pressure and finial-crack critical pressure, all these pressures were compared with the simulated stress inside the elements to get the conditions of initial-crack, propagation and finial-crack.When the two notched holes detonate at the same time, the stress in the middle point of the line, which connects the two holes center is obviously higher than it in same location by a single hole blasting.In V-shape notch blasting, excessive small uncoupling coefficient make other places of the tips of carving groove holes crack. And excessive large hole-distance makes it incapable to perforate between the two holes. Notch depth and notch angles are important parameters, and when the reasonable notch parameter is chosen, explosion energy is more centralized to the crack expanding direction.