Dynamic Numerical Simulation Of Water-coupling Cutting Blasting In Quarry

Cutting blasting technology is cutting rock along the predetermined direction by choosing proper blasting parameters and decoupled charging with the advantages of flat cutting surface and little or even no damage on the sides of rock. Cutting blasting develops on the basis of pre-splitting blasting(smoothing blasting), being applied widely in quarrying, and is a very promotional value of blasting technology. The paper made a further research to understand the crack formation mechanism of water-coupling cutting blasting by using dynamic numerical simulation software, and studied the impact of borehole distance and decoupling coefficient. There is significant value in theoretical and practical.In the paper, cutting blasting in Wulian granite quarry of Shandong province was introduced to analyze the crack formation mechanism of cutting blasting and the effects of cutting blasting due to variable blasting parameters. The plane strain model of elastic isotropy material was established according to practical project. By using explicit dynamic finite element analysis software, dynamic stress distribution and its variation law between two boreholes and around rock were detailed calculated subjected to explosive loading. At the same time, the cutting blasting crack formation mechanism was analyzed with fracture mechanics theory, as well as the influence of blasting effect due to different blasting parameters. The main research achievements and conclusions were as follows:According to the results of numerical calculation of initial hole wall stress and quasi-static stress field in air-coupling and water-coupling blasting, the conclusion was drawed:compared to air-decoupled structure in the same conditions, water-decoupled structure had a larger and longer interaction force both on the initial hole wall stress and the quasi-static stress field.Fracture mechanics was applied to figuring out the dynamic initial-crack critical pressure, propagation critical pressure and final-crack critical pressure. All these pressures were compared with the numerical simulation results to obtain the conditions when crack started, propagated and stopped.When the two adjacent holes detonated at the same time, the stress in the middle point of the borehole centerline was obviously bigger than that in the same place by a single hole blasting.In quarry cutting blasting, too small decoupling coefficient parameters will make the crack spread to all directions, simultaneously too big decoupling coefficient parameters will make the cracks between holes cannot perforate. Therefore, choosing proper decoupling coefficient and borehole distance can not only make the explosion energy more concentrate to cracks which are in the predetermined direction effectively, but also decrease the damage to rock mass.