1. School of Mechanics & Civil Engineering,China University of Mining and Technology( Beijing),Beijing　 100083,China; 2. Henan Key Laboratory for Green and Efficient Mining & Comprehensive Utilization of Mineral Resources,Henan Polytechnic University,Jiaozuo　 454000,China; 3. State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology(Beijing),Beijing　 100083,China

利用MTS 815试验机对深部煤岩组合体进行分级循环加卸载试验,研究了卸载过程中煤岩组合体轴向裂纹的张开效应,得出其轴向裂纹闭合应力(应变)和张开应力(应变)。研究结果表明:随着循环次数的增加,加载和卸载过程中煤岩组合体的裂纹闭合应力(应变)和张开应力(应变)具有增大的趋势;由于分级荷载的逐步增加,煤岩组合体产生新的裂纹,轴向裂纹闭合应变差、轴向裂纹张开应变差、轴向裂纹应力差随循环次数增大而增大;推导出轴向裂纹张开模型,并利用试验数据进行验证,模型理论值与试验值较为吻合,能有效描述卸载条件下轴向裂纹张开效应。

The test machine MTS 815 was applied to carry out cyclic loading-unloading experiments for coal-rock com- bined body. The axial crack recovery effect was analyzed and the axial crack closure stress (strain) and recovery stress (strain) were obtained. The results show that the axial crack closure stress (strain) and axial crack closure recovery stress (strain) increase with increasing cyclic times. Due to the increase of stress level,new cracks are generated,and the axial crack closure strain difference,axial crack recovery strain difference and axial crack stress difference increase with increasing cyclic times. Based on natural strain and engineering strain,the axial crack recovery model is proposed and verified by experimental data. The good agreement between theoretical data and test data shows the model is rea- sonable. Also,the proposed model can describe the axial crack recovery effect during unloading process well.

ZUO Jianping,CHEN Yan. Investigation on crack recovery effect of coal-rock combined body under the influence of unloading[J]. Journal of China Coal Society,2017,42(12):3142-3148.