深孔预裂爆破不同孔间距下裂隙演化规律

Evolution Laws of Cracks Under Different Hole Pitch in Deep Hole Pre-splitting Blasting

运用LS-DYNA对控制孔距离爆破孔不同间距的煤体进行深孔预裂爆破数值模拟，研究控制孔距爆破孔的远近对裂隙演化规律的影响，结果得出：受应力波与自由面反射效应的拉应力叠加作用，距离控制孔3m的爆破孔周围能够形成10-13条的主裂纹，且其中存在的长裂纹甚至几乎贯通煤体，对煤体尖端应力强度好于4．5m孔间距。通过试验区内将抽采孔瓦斯浓度和瓦斯抽采纯量作为2项指标在距离爆破孔3m和4．5m范围内进行对比，得出孔间距3m时比4．5m时要明显增加，说明孔间距为3m时增强了钻孔周围的卸压效应，证明试验区有效卸压半径为3～4．5m，与数值模拟结果吻合。

In order to research the influence of the distance from a control hole to a blasting hole on the evolution laws of fractures, fi- nite element software LS - DYNA is used to carry out pre - splitting blasting of deep hole for different distance coal. It is concluded that under the effect of tensile stress superposition from stress wave and free surface reflection effect, blasting hole 3 m around the control hole can form 10 to 13 main cracks. And there is a long crack that even almost cuts through coal mass, and the stress strength on coal cutting edge is better than 4.5 m hole pitch. The hole spacing of 3 m is significantly increased than 4.5 m according to the comparation of the different from the data between extraction hole gas concentration and gas extraction pure amount within the scope of 3 m and 4. 5 m. Hole spacing of 3 m is better than the other, and the pressure relief effect could be enhanced. The result proved that the effective pressure relief test area radius is 3 m to 4.5 m. which accords with the results of numerical simulation test.