School of Resource and Safety Engineering,China University of Mining & Technology (Beijing),Beijing　 100083,China

为研究冲击载荷下组合煤岩的动态力学特征，利用75 mm的分离式霍普金森压杆(SHPB)实验系统，对不同组合比煤岩样(砂岩∶煤∶砂岩分别显1∶1∶1,2∶1∶1，1∶1∶2，1∶2∶2)进行不同速率(4.590～8.791 m/s)的冲击加载实验，获得了组合煤岩的动态应力-应变曲线，结合煤、岩本构的研究成果和层叠模型原理，并充分考虑了组合煤岩体在动态破坏过程中的应变率相关性和损伤特性，构建了7参数组合煤岩层叠本构模型。研究结果表明∶① 不同组合比煤岩的弹性阶段和塑性阶段持续时间不同，不同组合比煤岩的应力应变曲线前期均呈现出明显的非线性;② 组合煤岩动态冲击屈服强度随应变率的增大而增大，随煤的占比增大而减小;③ 构建的7参数组合煤岩层叠本构模型数值拟合曲线与实测动态本构曲线具有较好的一致性，拟合参数分析发现在中应变率(110.41～195.49 s-1 )冲击载荷作用下，组合煤岩体损伤软化效应超过应变率强化效应成为主导因素;④ 拟合参数范围和试样冲击破坏特征均表明，组合体试件主要破坏部位以煤体破坏为主，不受组合方式的影响。研究成果为进一步深入认识冲击地压等煤岩动力灾害发生机理和预测预防措施提供参考借鉴。由于组合煤岩冲击破坏SHPB实验条件有限，并未考虑围岩影响，围压下的组合煤岩动态破坏特性有待利用实验和数值模拟手段进一步研究。

In order to study the dynamic mechanical characteristics of combined coal rock under impact load,using a ϕ75 mm split Hopkinson pressure bar ( SHPB) experimental system for the different combinations of coal samples (sandstone:coal:sandstone,1 ∶ 1 ∶ 1,2 ∶ 1 ∶ 1,1 ∶ 1 ∶ 2,1 ∶ 2 ∶ 2),the impact loading experiments at different rates (4. 590-8. 791 m / s) were carried out. The dynamic stress-strain curves of the combined coal rock were obtained. Combined with the research results of coal and rock constitutive model and the principle of overlay model,the strain rate correlation and damage characteristics of combined coal-rock mass in dynamic failure were fully con-sidered,and the seven-parameter combined coal rock layer constitutive model was constructed. The results show that ① The elastic and plastic phases of coal rock with different combination ratios have different durations,and the stress-strain curves of different combinations have obvious nonlinearity in the early stage. ② The dynamic impact yield strength of the combined coal rock increases with the increase of the strain rate,and decreases with the increase of the proportion of coal. ③ The numerical fitting curve of the 7-parameter combination coal-rock layer constitutive model is well consistent with the measu-r1ed dynamic constitutive curve. The fitting parameter analysis finds the medium strain rate (110. 41-195. 49 s ) impact load. Under the action,the damage softening effect of the combined coal-rock mass exceeds the strain rate strengthening effect and becomes the dominant factor. ④ The fitting parameter range and the impact damage characteristics of the sample indicate that the main damage part of the combined specimen is mainly caused by coal damage,not affected by the combination mode. The research results provide a reference for further understanding the mechanism of coal-rock dynamic disasters such as rock burst and predicting preventive measures. Due to the limited experimental conditions of SHPB for the impact damage of combined coal rock,the influence of surrounding rock is not considered. The dynamic failure charac-teristics of combined coal under confining pressure need to be further studied by experimental and numerical simulation methods.

XIE Beijing,YAN Zheng. Dynamic mechanical constitutive model of combined coal-rock mass based on overlay model [J]. Journal of China Coal Society,2019,44(2):463-472.