径向不耦合装药爆破下页岩的动态应变分布及损伤分形特征

Dynamic Strain Distribution and Damage Fractal Characteristics of Shale under Radial Uncoupled Charge Blasting

为研究径向不耦合装药结构对炸药能量的传递和爆破效果的影响,提高炸药能量利用率,增强岩体破碎效果,通过将直径为50 mm,高度为100 mm的标准页岩试件钻孔后装填二硝基重氮酚,控制45 mg的小药量,同时设置1、1.5、2、2.5四种径向不耦合装药系数,进行爆破模型实验。通过超动态应变测试系统、互补集合经验模态分解方法处理试件轴向各测点应变波形,分析试件不同段应变规律,并基于计盒维数理论,计算比较应变变化以及各测点处截面的损伤分形维数,对比试件不同区段裂纹开展情况,结合应变曲线对四种径向不耦合系数爆炸能量传播规律进行分析。结果表明:通过对比应变曲线,总体上拉应变峰值大于压应变峰值,试件受到较大且反复的拉、压应力后,最终发生破坏。实验表明径向不耦合系数为1.5时显著提高炸药能量利用,能延长爆生气体作用时间。不耦合装药结构试件截面的损伤分形维数从上至下呈n型变化,当系数为1.5时试件各段损伤分布最均匀,裂隙区能充分扩展,爆破效果最好。

To investigate the impact of a radially uncoupled charge structure on energy transfer and blasting effects of explosives,with the goal of improving energy efficiency and enhancing rock crushing,dinitrodiazophenol was placed in a standard shale specimen with a diameter of 50 mm and a height of 100 mm.A blasting model experiment was conducted using four radial uncoupled charge coefficients-1,1.5,2 and 2.5.The strain waveforms in the axial direction of the specimen were analyzed using the ultra-dynamic strain testing system and the complementary set empirical mode decomposition method.The strain behavior of different sections of the specimen was studied,along with the damage fractal dimension and crack development in these sections.The analysis of the explosive energy propagation laws,combined with the strain curve,revealed that the tensile strain peak values were generally higher than the compressive strain peak values.The specimen eventually failed after experiencing significant and repeated tensile and compressive stresses.Importantly,when the radial uncoupling coefficient was 1.5,the energy utilization of the explosive was significantly improved,along with the prolonged action time of the detonating gas.Additionally,the damage fractal dimension of the specimen section with an uncoupled charge structure changed from top to bottom in an“n-type”manner,resulting in the most uniform damage distribution across each section,a fully expanded crack area,and the best blasting effect.