直眼掏槽空孔效应的计算模型改进与分析

Improvement and analysis of calculation model for empty hole effect in parallel cut

为研究直眼掏槽时空孔周围岩体的破坏原理,准确计算空孔效应产生的集中应力值,对原有单空孔爆破时空孔效应的计算模型进行改进。改进模型考虑空孔布置区域和爆破应力方向的影响。采用弹性力学理论推导爆破应力作用下的空孔效应计算公式,并对改进模型进行分析与验证。分析与验证表明:空孔半径增大、空孔与炮孔间距减小时空孔效应越明显;空孔周围拉应力分布区域约为炮孔与空孔圆心连线处近空孔壁侧的±30°之间;孔壁处最大压应力出现在±70°左右处。与原有计算模型相比,改进后模型能更好反映实际爆破时的空孔效应。

When the parallel cut is employed, in order to study the failure mechanism of the rock mass around empty hole, and accurately calculate the stress concentration caused by the empty hole effect, the model for calculating the empty hole effect of single hole blasting is improved. The improved model considers the influence of the arrangement of holes and the direction of blasting stress. The formula concerning on the empty hole effect under the blasting stress is deduced using elastic mechanics theory, and the improved model is analyzed and verified. Analysis and verification show that larger radius and smaller spacing of the empty hole correspond to more obvious empty hole effect. The distribution area of the tensile stress around the empty hole is about ±30 degrees near the hole wall at the line connecting centers of the blast hole and the empty hole. The maximum compressive stress at the hole wall appears at about ±70 degrees. Compared with the original calculation model, the improved model can better describe the empty hole effect during actual blasting.