An investigation of energy consumption variation in rock blasting breaking with the resistance line
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摘要: 针对爆炸荷载下岩体破碎块度和有用功能耗及能耗利用率问题,运用断裂力学、分形基础理论分析和模型实验等方法,对爆炸荷载下岩体破碎块度和能耗利用率随最小抵抗线的变化规律开展了系统的分析研究。研究结果表明:在模型实验条件下,破碎块度分形维数在1.2~1.7之间,随最小抵抗线增大呈现较好的线性衰减趋势;破碎能耗随最小抵抗线呈现先增加后降低的趋势,爆炸能量利用率在4.57%~12.51%之间,趋势与能耗值一致,模型实验中能耗利用率存在最大值;破碎块度与能耗利用率变化趋势相反,说明在最小抵抗线变化过程中存在一个最佳值,使得破碎块度和能耗利用率均处于最优状态,模型实验中这一最佳值为160 mm,是装药直径的26.7倍。该研究结果可为提高爆炸能利用率理论分析及工程中降低大块率的设计和施工提供理论依据。Abstract: The topics such as fragmentation degree, active energy consumption and energy consumption efficiency of rock mass under explosive load have attracted increasing attention in recent years. However, it is very difficult to conduct such research due to its instantaneity, high temperature and high pressure characteristics. Systematic analysis and research on broken blocks of rock mass and the variation of energy utilization under explosion load with the different minimum resistance lines have been carried out. Plain concrete material was used to construct the model and carry out the model experiment. Theory of energy consumption in fracture mechanics was used to calculate the crushing energy. The basic fractal theory was used to calculate and analyze the fragmentation distribution law. Research results indicate that: the fractal dimension of broken blocks is between 1.2 and 1.7, exhibiting a good linear attenuation trend with the increase of the minimum resistance line from 120 mm to 200 mm; the crushing energy consumption increases first and then decreases. More specifically, the crushing energy consumption is 440.0 J at 120 mm, and increases to the maximum of 1 106.5 J at 180 mm, and then decreases to 1 084.8 J at 200 mm. The explosive energy utilization rate is between 4.57% and 12.51% and the maximum value corresponds to the minimum resistance line of 180 mm, the variation trend is consistent with that of the energy consumption value. The trend of broken fragmentation and utilization rate of energy consumption is opposite. There is an optimum minimum resistance line, corresponding to the optimized fragmentation degree and energy consumption utilization rate, in the model experiment is 160 mm which is 26.7 times the diameter of the charge. The research results can provide a theoretical basis for improving the explosive energy utilization rate and guide the design and construction processes in future engineering applications.
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Key words:
- fragmentation /
- energy explosion /
- energy efficiency /
- fractal dimension
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表 1 材料物理力学参数
Table 1. Physical and mechanical parameters of materials
密度/(kg∙m−3) 纵波波速/(m∙s−1) 泊松比 抗压强度/MPa 弹性模量/GPa 断裂韧性/(MPa∙m1/2) 1 850 2 326 0.235 8.38 10.02 1.50 表 2 炸药性能
Table 2. Explosive performance
炸药类别 线密度/(kg∙m−1) 爆热/(kJ∙kg−1) 爆力/mL 爆速/(m∙s−1) 黑索金 0.025 5600 480 8300 表 3 爆破参数
Table 3. Parameters of blasting
编号 孔深/mm 药卷直径/mm 药量/g 装药长度/mm 单耗/(kg·m−3) 最小抵抗线/mm 1 225 6 1.58 40 0.49 120 2 245 0.33 140 3 265 0.24 160 4 285 0.17 180 5 305 0.13 200 表 4 岩块累计质量占比
Table 4. Cumulative mass ratio of rock blocks
抵抗线/mm 爆堆质量/kg 不同尺寸破碎块体长度分布占比 <50 mm <70 mm <90 mm <110 mm <130 mm <150 mm 120 20.60 0.17 0.39 0.51 0.62 0.79 1 140 28.90 0.13 0.30 0.48 0.59 0.78 1 160 42.04 0.14 0.29 0.46 0.58 0.77 1 180 55.39 0.13 0.31 0.45 0.57 0.77 1 200 57.66 0.10 0.25 0.35 0.55 0.75 1 表 5 拟合函数
Table 5. Fitting function
抵抗线/mm 拟合函数 D R2 120 ln yi=1.38 ln(xi/12) 1.62 0.97 140 ln yi=1.49 ln(xi/12) 1.51 0.96 160 ln yi=1.55 ln(xi/12) 1.45 0.97 180 ln yi=1.59 ln(xi/12) 1.41 0.98 200 ln yi=1.72 ln(xi/12) 1.28 0.96 表 6 破碎能分布参数
Table 6. Parameter of fragmentation energy
抵抗线/
mm破碎质量/
kg原表面积/
m2岩块表面积/
m2新增表面积/
m2破碎能/
J破碎体积/
(10−3 m3)破碎能耗密度/
(kJ·m−3)破碎能利用率/
%120 20.60 0.15 1.13 0.98 440.0 11.13 39.51 4.97 140 28.90 0.19 1.50 1.31 589.5 15.62 37.73 6.66 160 42.04 0.24 2.13 1.89 848.7 22.72 37.35 9.59 180 55.39 0.29 2.75 2.46 1106.5 29.94 36.96 12.51 200 57.66 0.30 2.71 2.42 1084.8 31.16 34.80 12.26 -
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