Numerical modeling of the energy dissipation and fragmentation of copper-bearing rock under impact load
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摘要: 为了研究冲击荷载作用下含铜矿岩的破碎块度与能量耗散关系,借助分离式霍普金森压杆试验装置,分析不同冲击荷载下含铜凝灰岩的力学特性及能量传递规律,结合分形理论构建耗散能与矿岩破碎块度之间关系。同时基于有限离散元方法(finite discrete element method,FDEM)模拟矿岩的裂纹扩展行为。结果表明:随着入射能的增加,透射能、耗散能、反射能三者的能量分布规律基本保持一致,即透射能、耗散能、反射能依次降低;根据耗散能的不同,碎石块度分布也呈现出明显的差异性。当耗散能由19.52 J提升至105.72 J时,矿岩的平均块度从27.98 mm降低至16.94 mm,分形维数提升了26.43%,表明耗散能越高,矿岩的宏观破碎程度越剧烈,破碎块度的数目越多,碎块粒径越小,均匀性越好;随着冲击荷载的增大,裂纹起裂时间缩短,拉伸裂纹数量占总裂纹数量的比重提高。FDEM数值计算方法的应用为深入解析岩石断裂破坏特性提供了新的思路。Abstract: To understand the relationship between fragmentation and energy dissipation in copper-bearing ore rock subjected to impact loading, a split Hopkinson pressure bar (SHPB) testing apparatus was employed to study the mechanical properties and energy transfer mechanisms of copper-bearing tuff under varying impact loads. Additionally, fractal theory was used to establish the correlation between dissipated energy and rock fragmentation. Utilizing the finite discrete element method (FDEM), numerical simulations of crack propagation within the rock were conducted. The results indicate that as the incident energy increases, the distribution patterns of the transmission energy, absorbed energy and reflection energy remain consistent, which are characterized by transmission energy, absorbed energy and reflection energy decreased successively. Furthermore, significant variations in fragment size distribution are observed with changes in dissipated energy. Specifically, as dissipated energy increases from 19.52 J to 105.72 J, the average fragment size decreases from 27.98 mm to 16.94 mm, while the fractal dimension increases by 26.43%. This suggests that higher dissipated energy results in more extensive macroscopic fragmentation, an increase in the number of fragments, smaller particle sizes and enhanced uniformity. As the impact load intensifies, the time to crack initiation decreases, and the proportion of tensile cracks relative to total cracks increases. The application of the FDEM offers new insights into the fracture and failure characteristics of rocks.
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表 1 含铜矿岩基本物理力学参数
Table 1. Basic physical and mechanical parameters of copper bearing rock specimen
编号 密度/(g·cm−3) 纵波波速/(m·s−1) 弹性模量/GPa 泊松比 抗压强度/MPa J-1 3.10 3 549 93.35 0.33 59.23 表 2 含铜矿岩的冲击实验数据
Table 2. SHPB test data of copper-bearing rock samples
编号 冲击气压/
MPa平均应
变率/s−1峰值应力/
MPaWI/J WR/J WT/J WD/J A-3 0.5 30.68 108.03 63.34 7.24 45.13 10.62 B-2 0.6 35.71 119.72 81.67 5.73 55.75 19.51 C-4 0.7 44.25 141.35 105.92 7.32 66.10 31.57 D-1 0.8 50.93 163.19 130.76 8.05 74.19 47.75 E-3 0.9 53.62 189.55 168.28 23.94 83.45 60.60 F-2 1.0 59.15 200.93 203.33 37.88 89.99 75.12 G-4 1.1 64.81 249.80 222.91 43.46 93.01 85.52 H-1 1.2 77.39 265.90 267.09 62.21 99.06 105.72 表 3 含铜矿岩破碎块度筛分试验结果
Table 3. Test screening results of crushed copper-bearing rock fragments
编号 W/J 各个等级粒径质量(0.01g) 平均块度/
mm<0.3 mm <0.5 mm <1.0 mm <2.0 mm <4.0 mm <9.5 mm <16.0 mm <19.0 mm <26.5 mm <37.5 mm B2-0.6 19.52 0.04 0.18 0.13 0.31 0.16 1.35 2.95 12.8 36.44 123.42 27.98 C4-0.7 31.58 0.09 0.13 0.25 0.55 0.64 3.03 4.50 18.16 91.39 51.51 23.29 D1-0.8 47.75 0.11 1.52 2.46 3.74 3.39 12.10 18.87 24.19 47.12 53.92 20.54 E3-0.9 60.61 0.07 0.12 0.32 0.79 0.78 9.06 25.52 33.49 55.18 20.42 19.62 F2-1 75.13 0.1 0.24 0.54 1.33 1.25 9.85 40.75 39.61 22.46 20.47 18.28 G4-1.1 85.53 0.15 0.37 0.75 1.55 1.38 16.84 44.16 30.27 69.63 0 16.92 H3-1.2 105.72 0.27 0.68 1.20 2.60 1.92 20.17 51.22 32.99 46.95 12.74 16.94 -
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