1. School of Mechanics and Civil Engineering,China University of Mining and Technology ( Beijing),Beijing　 100083,China; 2. State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology (Beijing),Beijing　 100083,China

利用煤岩组合体的单轴和三轴压缩试验结果,基于轴向裂纹应变,分析了其峰后渐进破坏特征。在此基础上,通过将峰后阶段的煤岩组合体概念化为裂纹体和基体两部分,建立了考虑自然应变的裂纹体在峰后裂纹贯通阶段的本构模型,然后考虑基体的弹性变形,最终得到煤岩组合体峰后阶段的非线性应力-应变关系。实例验证表明,该模型能较好地反映煤岩组合体峰后应变软化行为和残余强度。对模型的2个参数进行分析,结果表明:轴向裂纹扩展应变极值在单轴压缩时取得最大值,围压存在时远小于最大值;等效非弹性柔度与轴向裂纹扩展应变极值存在负相关关系,与能量跌落系数大致存在线性相关关系,表明等效非弹性柔度可间接评价煤岩组合体峰后破坏的脆性程度;等效非弹性柔度比轴向裂纹扩展应变极值对煤岩组合体峰后破坏行为的影响更明显。

Based on the axial crack strain,the post-peak pro-gressive failure characteristics of coal-rock combined body is analyzed using its uniaxial and tri-axial compression test data. On this basis,by dividing conceptually the coal-rock combined body in the post-peak stage into two parts, i. e. cracked body and basal body, the constitutive model of cracked body considering natural strain at the stage of post-peak crack coalescence is established,and then the elastic deformation of basal body is considered. Finally,the post-peak nonlinear stress-strain relationship of coal-rock com- bined body is obtained. The results show that the model can well reflect the post-peak strain softening and residual strength of coal-rock combined body. Then,the two parameters of the model are analyzed and it is found that the axial crack propagation strain extremum achieves the maximum value in uniaxial compression and is far less than the maxi- mum under confining pressure. The equivalent inelastic flexibility is negatively correlated with the axial crack propaga- tion strain extremum and approximately linearly correlated with the energy drop coefficient,indicating that the equiva- lent inelastic flexibility can indirectly evaluate the extent of post-peak brittleness of coal-rock combined body. Further- more,the influence of parameter equivalent inelastic flexibility on the post-failure behavior of coal-rock combined body is more obvious than that of parameter axial crack propagation strain extremum.

ZUO Jianping,SONG Hongqiang,CHEN Yan,et al. Post-peak progressive failure characteristics and nonlinear model of coal-rock combined body[J]. Journal of China Coal Society,2018,43(12):3265-3272.