炮孔间距对偏心不耦合装药贯通裂纹扩展的影响

Influence of blast hole spacing on penetrating crack propagation of eccentric uncoupled charge

为研究光面爆破中偏心不耦合装药炮孔间距对贯通裂纹扩展的影响,利用同心不耦合装药的孔壁压力计算公式并结合应力波叠加原理,推导偏心不耦合装药的炮孔间距计算方法。基于求得的炮孔间距范围,计算3种岩石介质在不同炮孔间距条件下贯通裂纹的扩展位置,并选择砂岩材料进行数值模拟。结果表明:偏心不耦合装药爆破中,贯通裂纹主要集中于偏心侧;抗拉强度大的岩石,贯通裂纹偏离炮孔连心线的程度也较大。砂岩的炮孔间距为60 cm时,贯通裂纹扩展方向与炮孔连心线重合,连心线下方出现裂纹比较集中的贯通区域;炮孔间距的增大导致贯通裂纹远离炮孔连心线,从而造成欠挖。偏心不耦合装药爆破后,偏心侧岩石的损伤明显大于非偏心侧。

In order to study the influence of hole spacing of eccentric uncoupled charge on the penetrating crack propagation in smooth blasting,this paper first deduced the calculation method for hole spacing of eccentric uncoupled charge by using the formula of hole wall pressure of concentric uncoupled charge and the superposition principle of stress wave.Then,based on the obtained range of hole spacing,the propagation positions of penetrating cracks in three kinds of rock under different hole spacings were calculated.Finally,sandstone material was selected for numerical simulation.The results show that the penetrating crack is distributed on the eccentric side in eccentric uncoupled charge blasting and that the rock with high tensile strength has a large degree of deviation from the hole connection center line.When the hole spacing of sandstone is 60 cm,the propagation direction of penetrating crack coincides with the center line of the hole,and concentrated penetrating crack area appears below the center line.The increase of the hole spacing causes the penetrating crack to move away from the center line,resulting in under-excavation.After the eccentric decoupled charge blasting,the damage of rock on the eccentric side is obviously greater than that on the non-eccentric side.