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《Chinese Journal of Rock Mechanics and Engineering》 2006-11
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SHAN Renliang CHENG Ruiqiang GAO Wenjiao (School of Mechanics and Civil Engineering,China University of Mining and Technology,Beijing 100083,China)  
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 E_b-E(ε_i) to E_b,where E_b is the initial elastic modulus and E(ε_i) 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 (?)_1 is used to describe the low strain rate response of anthracite;and the other one with high relaxing time (?)_2 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.
【Fund】: 国家自然科学基金(50374070)
【CateGory Index】: TD313
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