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| Parameters determination of coal-rock HJC model and research on blasting characteristics by liquid CO2 |
| ZHANG Jiafan，GAO Zhuang，CHENG Shufan，ZHANG Huimei |
| (College of Science，Xi'an University of Science and Technology，Xi'an，Shaanxi 710054，China) |
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Abstract Holmquist-Johnson-Cook(HJC) constitutive model is widely used in numerical simulation of impact explosion engineering. In order to explore reasonable model parameters for coal-rock mass，furthermore to determine actual effect and related cracking range by liquid CO2 blasting，this article is relied on CO2 blasting project in a mining area in Shenmu of northern Shaanxi，based on static mechanical characteristics test and a split Hopkinson pressure bar(SHPB) impact test，the basic physical and mechanical parameters of coal-rock are obtained. By orthogonal experiment and numerical simulation methods，the entire process of the SHPB impact compression test is reproduced on LS-DYNA3D platform. According to Person correlation coefficient，this research judges the fitting degree between experiment and simulated strain signal，then backward deduces the main sensitive parameter B and N of HJC model. Introducing *MAT-ADD-EROSION failure condition and using compressive and tensile failure criteria，it truly reproduces the whole process of crack initiation，expansion and penetration，until a fissure zone is formed for CO2 blasting，which effectively simulates the fragmentation characteristics of blasting rock mass，and reflects the geometric nonlinear characteristics of rock mass in working face. Moreover，this study analyses crack propagation characteristics and blasting effect of CO2 blasting compared with traditional explosive blasting. Subsequently，the stress wave attenuation laws are analyzed，which give the crushing and fissure range. The results show that the process of stress wave attenuation and the energy release slopes relatively gently during liquid CO2 blasting，and the energy mainly produces elongated cracks in fissure area，which is much larger than the traditional explosive blasting. Under the same equivalence，comparing with traditional explosive blasting case，the effective range of liquid CO2 blasting is larger，meanwhile the crushing range is decreased，and the cracking range is increased. Correspondingly，coal rock is felled apart into massive fragmentations. The research results are applied to the industrial test of CO2 blasting in this mine，considering the simultaneous action of four crack devices，blasting holes are set in a square shape with a spacing of 0.7 meters which determined by calculating. The test results show that the actual blasting effect is good，lump coal rate is increases by 38.5% compared with tradition case.
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2021, Vol. 40 
