Discrete Element Simulation of Blasting Damage Characteristics of Granite under Different Decoupling Coefficients
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摘要: 为研究径向装药不耦合系数对花岗岩爆破损伤程度的影响,在考虑爆炸冲击波和爆生气体共同作用的基础上,提出了一种“动”、“静”荷载混合施加的PFC爆破模拟方法,采用该方法分别进行了6种不耦合系数下花岗岩爆破过程的数值模拟。模拟结果显示,随着装药不耦合系数的增大,花岗岩爆破损伤程度先增强后减弱。耦合装药下,爆生裂纹数量为9367;不耦合系数为1.2时,裂纹数量增加至最多,为24975;不耦合系数为2.0时,裂纹数量减少为292。对比耦合装药和不耦合系数为1.4时的花岗岩损伤模式发现,爆生气体的准静态压力对爆生裂纹的扩展具有重要作用。根据不同不耦合系数下的爆生裂纹数量,建立了不耦合系数大于或等于1.2时的岩石爆破损伤程度预测模型,拟合度达0.9808。该预测模型对爆破施工设计等工作具有一定的参考意义。Abstract: In order to study the effect of charge decoupling coefficients on the extent of granite blasting damage, a particle flow code (PFC) blasting simulation method with mixed “dynamic” and “quasi-static” loads is proposed based on the joint action of blast shock wave and detonation gas, and then the numerical simulation of granite blasting process under six decoupling coefficients was carried out. The results show that the extent of granite blasting damage increases and then decreases as the decoupling coefficients increases; the number of blasting induced cracks under coupled charge is 9367, which increases to 24975 when the decoupling coefficient is 1.2, and then decreases to 292 when the decoupling coefficient is 2.0. Comparing to the damage pattern under coupled charge, the extension distance of blasting induced crack is obviously shorter when the decoupling coefficient is 1.4, which indicates that the quasi-static pressure of blast gas plays an important role in crack extension. According to the number of blasting cracks, the prediction model of rock blasting damage under different decoupling coefficients greater than or equal to 1.2 was established, and the fitting degree reaches 0.9808. The prediction model presented in this paper is of certain reference significance for practical blasting design.
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Key words:
- granite /
- decoupling coefficient /
- explosion damage /
- crack /
- particle flow code
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表 1 主要细观参数
Table 1. Main microscopic parameters
Linear contact parameters Rmin/m Rmax/Rmin ${\bar E{_{\rm l}} }$/GPa ${\bar k{_{\text{n} }} }$/${\bar k{_{\text{s}} } }$ ${\mu {_{\text{c} }} }$ 0.028 1.66 45 2.5 1.0 Parallel bond parameters ${\bar \sigma {_{\text{n} }} }$/MPa ${\bar \sigma {_{\text{s} } }}$/MPa ${\bar E{_{\rm p}} }$/GPa ${\bar K{_{\text{n} } } }$/${\bar K{_{\text{s} } } }$ ${\varphi {_{\text{c} } } }$/(°) 72 150 45 2.5 30 表 2 试样的主要力学参数
Table 2. Main mechanical parameters of the sample
Method ${E{_{\text{t} } } }$/GPa ${\sigma {_{\text{t} } } }$/MPa ${v{_{\text{t} } } }$ $\,\rho $/(kg·m−3) Experiment 21.4 – 63.7 137.7 – 163.8 0.23 – 0.26 2650 – 2740 Numerical simulation 27.2 150.93 0.24 2700 表 3 不同不耦合系数对应的炮孔半径
Table 3. Blasthole radius vs. decoupling coefficient
$\zeta $ rp $\zeta $ rp 1.0 0.060 1.6 0.096 1.2 0.072 1.8 0.108 1.4 0.084 2.0 0.120 -
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