台阶爆破岩石破碎楔块理论及数值模拟研究

Wedge Theory of Rock Fragmentation for Bench Blasting and its Numerical Simulation

在逐排或齐发爆破情况下,一般没有考虑岩石在单个炮孔爆破后产生的空间破碎形态问题。岩石在爆炸作用下产生的空间破碎形态主要受岩石性质,自由面状况、炸药性能等因素影响。逐孔起爆改变了岩石的自由面状况,进而对爆破效果产生了较大的影响。根据露天台阶爆破逐孔起爆条件下岩石动态破碎特征,提出了露天台阶爆破岩石破碎楔块理论,分析了逐孔起爆条件下,体积公式计算炮孔装药量的局限。采用有限元软件ABAQUS/EXPLICT中的CEL方式加载爆炸载荷,并结合混凝土塑性损伤本构(CDP)建立了双坡面三维台阶爆破模型,得到了不同时刻岩体内应力分布云图和裂纹扩展以及损伤演化情况。模拟结果表明:岩石爆破破碎楔块理论更加接近逐孔起爆条件岩石破碎状况,并有利于炮孔装药量计算。

In row-by-row or simultaneous blast, generally the rock fragmentation shape problem is not taken into account after a single borehole initiation. The rock fragmentation shape under the blasting is primarily influenced by the rock property, free surface condition and explosive property. The free surface condition is changed by hole-by-hole initiation, which has great influence on the blasting effect. The wedge shape theory of the rock fragmentation range in open-pit blasting is presented according to the dynamic characteristics of rock fragmentation of open-pit bench blas- ting under the condition of hole-by-hole initiation. The volume formula has certain limitations in the calculation of borehole charge. The dual slope three-dimensional bench blasting model is established, and the explosion load through the CEL way of the finite element software ABAQUS/EXPLICIT, and the concrete plastic damage constitutive model（CDP） are adopted. The rock mass stress contours, crack propagation and damage evolution of different mo- ments are obtained. The results show that the wedge shape theory of blasting is closer to the rock fragmentation in hole-by-hole blasting and further helpful to design and calculate the charge weight.