孔内起爆位置对爆破振动场分布的影响作用规律

岩石钻孔爆破中，孔内起爆位置决定炸药爆轰波的传播方向，进而影响爆破振动场的分布。通过分析柱状药包爆轰产物和爆炸能量的分配及其爆炸应力场的分布，揭示了起爆位置的影响作用机理；基于Heelan短柱解延长药包叠加计算模型，比较分析了不同起爆位置下爆破振动场的分布规律，并结合现场实验，验证了起爆位置对爆破振动场分布的调节作用效果。结果表明:起爆位置的影响作用机理在于柱状药包爆炸能量的轴向不均匀分配和爆破振动场叠加的相位延迟效应；孔内起爆位置对爆破振动场的分布起调节作用，爆破振动沿爆轰波传播正向叠加增强，且爆破振动场分布的不均匀性受药包长度和炸药爆轰速度的调控；对于常见的几种起爆方式，现场实验统计结果显示，底部起爆时地表爆破振动峰值最大，中部起爆次之，上部起爆最小，且爆破振动差异性随炮孔深度的增加而增大，但振动差异会随距离逐渐消减。

Acting law of in-hole initiation position on distribution of blast vibration field

In rock drilling and blasting, the in-hole initiation position determines the propagation direction of the explosive detonation wave, and thereby affects the distribution of blast vibration field (BVF). In this study, the acting mechanism of the initiation position was investigated via the comprehensive analysis of the distribution of the detonation products, the explosion energy as well as BVF of the cylindrical charge. Then, the distribution law of BVF under different initiation positions was analyzed using the Heelan’s short-column-solution based superposition model of an extended charge. At last, the acting effect of the initiation position on the distribution of BVF was demonstrated by the onsite blasting experiment. Results indicate that the acting mechanism of the initiation position lies in the axial non-uniform distribution of the explosive energy and the phase delay effect of the superposition of BVF. The in-hole initiation position has the adjustment effect on the distribution of BVF, due to which, the blast vibration amplitude is strengthened at the forward direction of the detonation wave. It needs to be pointed that the non-uniformity of the distribution of BVF is under some control of the explosive length and the explosive velocity of detonation. For the common initiation modes, the field test results indicate that the ground peak particle velocities under the bottom are larger than those under the top and mid-point initiations, and the top initiation is the smallest. Besides, the blast vibration differences becomes more obvious as the blast-hole depth increases, but the vibration difference gradually vanishes with distance.