双孔台阶延期爆破效应的数值模拟研究

Numerical Simulation Research on Delayed Double-hole Bench Blasting Effect

为了研究孔间延期对台阶爆破效果的影响,基于ABAQUS进行双孔双坡面台阶精确延时爆破的数值模拟研究,分析不同延时爆破条件下双孔台阶结构的应力波传播规律、拉伸与压缩损伤发展和振动效应。结果表明:越接近于自由表面,岩体中的质点应力峰值和振速峰值越大,损伤区域越明显;在台阶顶面,随着爆心距的增加,各测点Y向(水平)振速峰值呈现出先减小后增加之后再减小的趋势,同时最大Y向(水平)振速测点位于150 mm(1.25倍孔距)处,Z向(竖直)振速峰值随爆心距的增加逐渐减小;随着孔间延时的增加,岩体损伤单元体积(D>0.6)在小范围内降低后不断增大,并于孔间延时为60μs时达到峰值,且随着延时的进一步增加,损伤体积逐渐降低并趋于稳定值;同时,岩石内两孔间测点应力在孔间延时为60μs时达到峰值,台阶顶面处振动效应逐渐降低并于50μs时趋于稳定;孔间延时为60μs,也即是0.5 ms/m(孔间延时与孔距比值)为本模型最佳爆破孔间延时。

In order to study the influence of delay time on bench blasting,a numerical simulation study on precise delay blasting of a double-hole and double-slope bench was carried out by ABAQUS.The main contents of the research include the stress wave propagation law,the development of tensile and compression damage and the vibration effects of the double-hole bench structure with different delays.The results show that the closer to the free surface,the greater the peak stress and peak particle vibration velocity in the rock mass,and the more obvious the damage area.Meanwhile,on the top surface of the bench,with the increase of distance to blast source,the peak particle vibration velocity in Y direction(horizontal)at each measuring point showed a decreasing increasing-decreasing trend.At the same time,the measuring point with the maximum Y direction(horizontal)velocity is located at 150 mm(1.25 times the hole spacing).The peak particle velocity of the Z-direction(vertical)decreases gradually with the increase of distance to blasting source.Besides,with the increase of time delay between holes,the volume of rock damage unit(D>0.6)decreases in a small range and then increases continuously.When the delay time is 60μs,the vibration velocity reaches the peak value.With the further increase of delay,the damage volume decreases gradually and tends to a stable value.At the same time,the stress of the measuring point between two holes in the rock reaches the peak value when the delay time between the holes is 60μs,and the vibration velocity at the top of the bench gradually decreases and tends to be stable at 50μs.Therefore,it can be considered that 60μs(0.5 ms/m)is the best delay time for this model.