小不耦合系数装药爆破孔壁压力峰值计算方法

基于轮廓爆破孔壁压力峰值计算方法的相关研究，充分考虑空气冲击波的传播与爆轰产物膨胀的过程，理论分析了小不耦合系数装药爆破过程中空气冲击波与炮孔壁的相互作用，建立了三维空气介质径向不耦合装药单孔爆破有限元模型，研究了工程爆破中常用的多种小不耦合系数装药组合工况下，炸药单点起爆后的炮孔壁压力峰值，并获得了相应工况下的孔壁压力峰值较爆生气体准静态等熵膨胀压力的压力增大倍数。结果表明:小不耦合系数装药爆破过程中，爆轰产物参数会对空气冲击波波后物质参数产生显著影响，揭示了小不耦合系数装药爆破与轮廓爆破在孔壁压力峰值计算方法上的本质差异；柱状装药结构爆轰波沿轴向传播使得空气冲击波撞击炮孔壁时存在叠加效应，孔壁压力峰值也相应增大，通过统计分析不同炸药类型、不同岩石类型工况下压力增大倍数与不耦合系数的关系，发现压力增大倍数随不耦合系数的增大近似呈线性增长；基于理论推导结果及常用爆破孔壁压力峰值计算形式，综合考虑炸药性能、孔壁岩石介质条件、不耦合装药系数对空气冲击波撞击炮孔壁后压力增大倍数的影响，提出了不耦合系数较小时爆破孔壁压力峰值计算方法。

A calculation method of the peak pressure on borehole wall for low decoupling coefficient charge blasting

The peak pressure on a borehole wall is an important parameter for the analysis of rock blasting rupture and the non-fluid solid coupling explosion impact dynamic response. Based on the relevant research of calculation methods for the peak pressure on the borehole wall for contour blasting, the interaction between the air shock waves and the borehole wall during low decoupling coefficient charge blasting was theoretically analyzed, and the influencing factors of pressure increase ratio were obtained by fully considering the process of air shock wave propagation and detonation product expansion. The parameters of detonation products were used instead of those of shock wave products in theoretical derivation. The single-hole finite element blasting model with radial decoupling charge for air medium was established, and the peak pressure of the borehole wall after single-point detonation of explosives was studied under the combination conditions of multiple low decoupling coefficient charge structure commonly used in engineering blasting. Moreover, the pressure increase ratio which was the ratio of the peak pressure on the borehole wall to the quasi-static isentropic expansion pressure of explosion gas was obtained under the corresponding conditions. The results show that in the process of explosive blasting with a low decoupling coefficient, there is no separation of air shock waves and detonation products, the parameters of the detonation products have a significant effect on the parameters after air shock waves, which in turn affects the interaction between the air shock waves and the borehole wall. It reveals the essential difference between the calculation methods for the peak pressure on the borehole wall in low decoupling coefficient charge blasting and contour blasting. In addition, the propagation of the axial detonation wave in the cylindrical charge structure causes a superposition effect when the air shock wave impacts the borehole wall, and the peak pressure increases accordingly. Through statistical analysis of the relationship between the pressure increase ratio and the decoupling coefficient under different explosive types and different rock types, it is found that the pressure increase ratio increases approximately linearly with the increase of the decoupling coefficient. Based on the the results of theoretical derivation and the commonly used calculation methods for the peak pressure on the borehole wall, a method for calculating the peak pressure on the borehole wall was proposed for low decoupling coefficient charge blasting by considering the effects of explosive characteristics, medium conditions of the borehole wall, and decoupling coefficient on the pressure increase ratio after the air shock wave colliding with the borehole wall.