孔间距对二氧化碳相变爆破效果的影响模拟分析

Simulation Analysis of Influence of Borehole Spacing on Effect of CO_(2) Phase Change Blasting

为研究采用液态二氧化碳相变爆破岩体的合理孔间距,通过能量换算公式计算得到ϕ5/1700型二氧化碳致裂管的爆破炸药当量,利用有限元软件模拟分析了孔间距分别为1.5、1.6、1.7、1.8、1.9、2.0 m时,液态二氧化碳相变爆破花岗岩过程中应力波传播规律和岩体裂纹扩展规律。结果表明:液态二氧化碳相变爆破岩体过程中,爆破应力波在两孔之间相遇叠加增强。两致裂孔中间位置岩体的最大有效应力与孔间距成反比;ϕ95/1700型二氧化碳致裂管应用于露天台阶开挖,在花岗岩地层中爆破时最优孔间距为1.9 m,而理论公式计算结果为1.66 m,说明理论公式计算结果偏保守。

In order to study the reasonable borehole spacing of rock mass by phase change blasting with liquid CO_(2),the explosive equivalent of ϕ95/1700 type CO_(2 )cracking tube was calculated by energy conversion formula.The stress wave propagation law and rock crack propagation law in the process of granite phase change blasting with liquid CO_(2) were simulated and analyzed by using finite element software when the borehole spacing is 1.5,1.6,1.7,1.8,1.9 and 2.0 m respectively.The results show that the blasting stress wave increases when it meets and overlaps between two holes in the process of phase change blasting with liquid CO_(2).The maximum effective stress of the rock mass in the middle of the two fracture causing holes is inversely proportional to the borehole spacing.The type of ϕ95/1700 CO_(2) cracking tube is applied to open-pit bench excavation.When blasting in granite stratum,the optimal borehole spacing is 1.9 m,and the calculation result of the theoretical formula is 1.66 m,indicating that the calculation result of the theoretical formula is conservative.