地下采场爆破炮孔堵塞效应及长度研究

为研究不同炮孔堵塞长度对采场爆破设计的影响,通过分析采场爆破炮孔堵塞效应,提出确定炮孔堵塞长度的条件;并对炮孔堵塞物的运动进行理论分析,结合所提出的条件推导出确定炮孔堵塞长度取值范围的函数模型,再将某工程实例相关参数代入函数模型,其中孔径120 mm,乳化炸药药条直径100 mm,采用连续装药,计算出孔底堵塞取值范围为l_w=0.7~1.3 m,孔口堵塞取值范围为l_h=0.9~1.6 m。同时利用有限元软件ANSYS/LS-DYNA建立4种不同装药结构的双孔起爆模型对炮孔堵塞长度的装药方案进行对比分析,得到在一定堵塞长度范围内漏斗深度与堵塞长度成正比;并对关键位置上单元的有效应力峰值进行分析得到本文模拟条件下采场爆破最佳堵塞长度为孔口1.6 m,孔底1.1 m,与数值计算结果基本一致。

Study on Blockage Effect and the Stem Length in Underground Stope Blasting

In order to study the influence of different hole stemming lengths on the blasting design of the stope, the condition of determining the stemming length of the hole was proposed by analyzing the clogging effect of the hole in the stope blasting. And the movement of stope plugging was analyzed theoretically. Combined with the condition of determining, the stemming length of the hole was derived to determine the function model of the range of the clogging length of the blast hole, and the relevant parameters of a project instance were substituted into the function model, in which the aperture was 120 mm, the diameter of the emulsion explosive strip was 100 mm, and the continuous charge was used. The value of the blockage at the bottom of the hole was 0.7~1.3 m, and the value of the blockage at the top was 0.9~1.6 m. At the same time, using the finite element software ANSYS/LS-DYNA, four kinds of double-hole detonation models with different charge structures were established to compare and analyze the charge schemes of the plugging length of the borehole, and the positive ratio between the depth of the funnel and the plugging length in a certain range of plugging length was obtained. By analyzing the effective stress peak value of the unit at the key position, it is concluded that the optimum stope blasting plugging length is 1.6 m at the top and 1.1 m at the bottom of the hole, which is basically consistent with the numerical results.