浅埋工作面顶板预裂分形爆破力学与模拟分析

Analysis on mechanical behavior and simulation of roof fractal pre-splitting blasting in shallow depth coal mining face

针对纳林庙二号井621-02浅埋工作面采用"直线"炮孔预裂爆破后,在基本顶初次断裂时产生强烈的矿压显现现象,基于对顶板预裂爆破机理和炮孔布置的分形几何理论分析,给出了不同炮孔布置方式的分形维数表达式,计算出"三角形"布置炮孔的分形维数为1.15,显著大于"直线"布置炮孔的分形维数1.0。据此提出了"三角形"布置炮孔预裂爆破的改进方案,利用有限元非线性动力学软件LS-DYNA对2种爆破方案的Mises应力演化规律进行数值模拟分析,结果表明:改进方案反射应力波的做功效果更好,应力波的衰减更慢,有利于爆炸产生的能量更充分地去破碎岩石。

According to a pre-splitting blasting of the straight line boreholes applied to No. 621- 02 shallow depth coal mining face in Nalinmiao No. 2 Mine,when a primary breaking of the basic roof occurred, a serious mine pressure behavior phenomenon would occurr. Based on the analysis of the pre-splitting blasting mechanism of the roof and the fractal geometry theory of the blasting borehole layout, the fractal dimension expression of the different blasting borehole layout mode was provided. The fractal dimension of the deha layout blasting boreholes was calculated as 1.15 and was obviously higher than the fractal dimension of the straight line layout blasting boreholes as 1.0. Therefore, the pre-splitting blasting improved plan with the deha layout blasting boreholes was provided. The finite element nonlinear dynamics software LS-DYNA was applied to the numerical simulation analysis on the Mises stress evolution law of the two blasting plans. The results showed that the work effect of the reflection stress wave for the improved plan would be better and the attenuation of the stress wave would be more slow and favorable to the blasting energy to fully break the rocks.