无底柱分段崩落法扇形孔起爆方式数值模拟研究

    Numerical simulation study of fan-shaped hole initiation mode with non-pillar sublevel caving method

    • 摘要: 扇形孔爆破落矿是无底柱分段崩落法开采过程中的关键环节,爆破后大块率、粉矿率直接关系着后续出矿作业的连续性。为了研究扇形孔起爆方式对爆破效果的影响,采用有限元软件LS-DYNA模拟了孔口和孔底两种起爆方式的爆破落矿过程,得到了孔口起爆和孔底起爆两种起爆方式下的应力场演化规律,计算了扇形孔孔口、中间、孔底三个位置的有效应力时程曲线,并进行了两种起爆方式的扇形孔爆破现场试验,对比了两种起爆方式的爆破效果。研究结果表明:扇形孔爆破产生的爆炸应力波在扇形孔孔口位置叠加较为密集,极易造成过度破碎和较大的粉矿率;爆炸应力波在扇形孔孔底位置较为稀疏,导致扇形孔孔底位置的大块率较高;孔口起爆和孔底起爆方式下,应力分布均表现为扇形孔孔口有效峰值应力>中间有效峰值应力>孔底有效峰值应力;现场试验表明孔底起爆的爆破效果优于孔口起爆,孔底起爆具有更低的大块率和粉矿率。扇形孔爆破采用孔底起爆和孔口间隔装药有助于降低大块率和粉矿率。

       

      Abstract: Fan-shaped hole blasting is a key link in the process of non-pillar sublevel caving method, and the lump rate and fine ore rate after blasting are directly related to the continuity of subsequent ore drawing operations. The finite element software LS-DYNA is used to simulate the blasting process of ore falling in various initiation modes in order to study the influence of the initiation modes of fan-shaped holes on the blasting effect. The evolution law of stress field under two initiation modes, orifice initiation and bottom-hole initiation, is obtained. The effective stress time-history curves of the fan-shaped hole at the orifice, the middle and the bottom-hole are calculated. The field tests of fan-shaped hole blasting with two initiation methods are carried out and the blasting effects of the two initiation methods are compared. The results show that the explosive stress waves are superimposed densely at the orifice of the fan-shaped hole, resulting in excessive crushing and fine ore. The explosion stress wave is sparse at the bottom of the fan-shaped hole, which leads to a large block at the bottom of the fan-shaped hole. The effective peak stress at the orifice of fan-shaped hole is greater than that at the middle and that at the bottom of the hole. The field test shows that the blasting effect of bottom-hole initiation is better than that of orifice initiation. The bottom-hole initiation has lower lump rate and fine ore rate. Using bottom-hole initiation and orifice interval charging in fan-shaped hole blasting is helpful to reduce the lump rate and fine ore rate.

       

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