Influences of cut parameters on blasting effect in rock roadway of coal mine

To improve the driving speed, by taking the tunnel blasting practice in Lushuidong coal mine as research background, the optimization of cut parameters was studied by LS-DYNA3D. Underground field experiments were combined to analyze the dynamic stress, hard rock-crushed range and underground blasting effect for the hard rock cut blasting with different parameters. The average effective stress peak, along the section of the cut center from the bottom of the hole to the top, increases by over 40% when the center holes are blasted as compared with that when the center holes are not blasted. Center hole blasting plays an important role in the formation of the groove bottom. Under the same conditions, when the explosive charge in each blasting hole increases from 1.2 kg to 1.8 kg, the average effective stress peak along that section increases by only 20%, the hard rock-crushed range increase by less, and the advance per attack adds within 10% in blasting practice. Field experiments show that the cut blasting depth increases by 31%-65% with center holes blasted as compared with that without center holes under normal blasting charge condition. When the cut angle is less than 78°, the blasting footage decreases slowly with the increasing of cut angle; when the cut angle increases to 82°, the blasting footage decreases obviously with the increasing of cut angle.