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Abstract Experiments performed on split Hopkinson pressure bar(SHPB) with a large diameter of 75 mm show that the dynamic stress-strain curve of anthracite of Yunjialing coal mine is of distinct plastic yield characteristics；and the initial elastic modulus，yield strength，as well as the ultimate strength go up with strain rate；but there is the best correlation between yield strength and the strain rate. Based on the characteristics of measured dynamic stress-strain curves and analysis of existing dynamic constitutive models of rock，as well as preparatory simulation，a new viscoelastic damage model has been introduced. A linear spring is put to parallel to two Maxwell units with different relaxing time to express distinct plastic flow，and the damage D is equal to the ratio of Eb－E(ei) to Eb，where Eb is the initial elastic modulus and E(ei) is the slope of the line between the origin point and any other point on the tested dynamic stress-strain curve. In the new constitutive model，one Maxwell unit with low relaxing time j1 is used to describe the low strain rate response of anthracite；and the other one with high relaxing time j2 to describe high strain rate response of anthracite. Simulated stress-strain curves using the new model is of good consistency with measured curves；and the simulated parameters indicate that the response of the low strain rate of anthracite is just as same as that of concrete；but the response of the high strain rate of anthracite is much more violent than that of concrete.
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Received: 29 September 2005
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LI Botao1, 2, 3, TAN Yuxuan1, LIN Haifei4, 5*, WEI Jianping1, 2, 3, ZHANG Hongtu1, 2, 3, LI Shugang4, 5, WEI Zongyong4, 5, WANG Pei4, LUO Rongwei4, LIU Yanwei1, 2, 3. Mechanical properties and mesoscopic damage evolution of coal under liquid-nitrogen freezing at different initial temperatures[J]. , 2026, 45(6): 1757-1772. |
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