Experimental study on the blasting effects of rich-iron ore with different explosives
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摘要: 为探究炸药类型对铁矿石爆破效果的影响,选用相同药量的3种炸药对铁矿石试样进行爆破试验。对比研究了不同炸药爆炸作用后试样表面裂纹分形维数和碎块块度分布特征,进而对试样的破坏程度和爆破效果进行了定量的对比与评价。同时,从爆炸应力波叠加、能量释放与传递角度,对爆破效果的差异进行了理论分析。研究结果表明:(1)松散装药以及混合装药均会导致爆源相同距离处爆炸应力场分布的均匀性变差;(2)炸药爆热越大、炸药铁矿石波阻抗匹配程度越高,炸药爆炸后释放的能量越大且能量传递效率越高,铁矿石破坏程度越大;(3)爆破工程中炸药选型时,应重点考虑炸药密度、爆热和爆速3个参数,选择与矿(岩)体波阻抗匹配程度高且爆热合适的炸药,使得爆破后产生的大块和小块均较少。Abstract: In order to investigate the influence of different explosives type on the blasting effects, three kinds of explosives with the same quality were used to carry out blasting test on iron ore samples. The fractal dimension of surface crack and fragment size distribution of specimens were comparatively studied, and then the damage degree and blasting effects of specimens were quantitatively compared and evaluated. At the same time, the differences of blasting effects are analyzed theoretically from the angle of explosion stress wave superposition, energy release and energy transfer. The results are as follows. (1) Both loose charge and mixed charge will cause the uniformity of the explosion stress field distribution to deteriorate. (2) The greater the explosion heat, the greater the energy released after explosion; the higher the wave impedance matching, the higher the energy transfer efficiency after explosive explosion. (3) In the selection of explosives in blasting engineering, three parameters of explosive including density, explosion heat and detonation velocity should be considered; Explosives with a high degree of wave impedance matching and appropriate explosion heat should be selected so that the bulk and small pieces generated after blasting are less.
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Key words:
- iron ore /
- blastability /
- blasting fragmentation /
- fractal dimension /
- wave impedance /
- explosion heat /
- detonation velocity
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表 1 岩体可爆性分级标准
Table 1. Classification standards of rock blastability
可爆性
等级天然裂隙程度、平均间距及分数 单轴抗压强度及分数 密度及分数 波阻抗及分数 总分数 可爆性
描述可爆性描述裂隙程度 l/m 分数 σc/MPa 分数 ρ/(g·cm−3) 分数 Zr/(Gg·m−2·s−1) 分数 Ⅰ 极度裂隙 <0.10 1 <80 1 <2.50 1 5.0 1 4 易爆 Ⅱ 强烈裂隙 0.30 2 100 2 2.75 2 7.5 2 8 中等可爆 Ⅲ 中等裂隙 0.75 3 140 3 3.00 3 10.0 3 12 难爆 Ⅳ 轻微裂隙 1.25 4 170 4 3.25 4 12.5 4 16 很难爆 Ⅴ 极少裂隙 >1.50 5 >180 5 >3.50 5 15.0 5 20 特别难爆 表 2 富铁矿矿体可爆性评价结果
Table 2. Blastability evaluation results of high-grade iron ore
评价指标 指标值 得分 权重 加权得分 总分 可爆性等级 l/m 1.25 4 1.2 4.8 18.8 Ⅴ(特别难爆) σc/MPa 227 5 1.0 5.0 ρ/(g·cm−3) 4.25 5 0.7 3.5 Zr/(Gg·m−2·s−1) 24 5 1.1 5.5 表 3 炸药参数
Table 3. Explosive parameters
试验 炸药 质量/g 直径/mm 高度/mm 密度/(g·cm−3) 爆热/(kJ·kg−1) 爆速/(km·s−1) 波阻抗/(Gg·m−2·s−1) 匹配系数 A DDNP 1 6 63 0.56 1 811 3.529 1.976 0.082 B DDNP+RDX 1 6 59 0.61 3 494 3.975 2.425 0.100 C 单发雷管 1 6 31 1.13 4 167 5.173 5.845 0.242 表 4 爆破块度分布函数参数
Table 4. Parameters of blasting fragmentation distribution function
试验 炸药 试样 G-G-S分布函数参数 相关系数 x0/mm n A DDNP A-1 268.7 2.87 0.964 8 A-2 275.4 2.92 0.976 7 B DDNP+RDX B-1 253.6 5.95 0.976 0 B-2 249.8 7.22 0.976 3 C 雷管 C-1 230.3 2.60 0.962 3 C-2 224.0 2.54 0.993 3 表 5 爆破块度分布评价指标
Table 5. Evaluation indexes of blasting fragmentation distribution
试验 炸药 试样 d10/mm d50/mm d90/mm d90/d50 dmax/mm 实验 平均 实验 平均 实验 平均 实验 平均 实验 平均 A DDNP A-1 120 123 211 214 259 262 1.23 1.23 269 272 A-2 125 217 266 1.22 275 B DDNP+RDX B-1 172 177 226 226 249 248 1.10 1.09 254 252 B-2 182 227 246 1.08 250 C 雷管 C-1 95 93 176 173 221 218 1.25 1.26 230 227 C-2 90 170 214 1.26 224 -
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