含层理岩石单轴损伤破坏声发射参数及能量耗散规律

摘要

Bedding structures are widespread and has a tremendous threat to stability of mine pillars.In this paper,the uniaxial compression tests (UCT) and CT scanning tests have been carried out on bedding rock and homogeneous massive rock.Through the analysis of acoustic emission (AE) characteristics,energy dissipation and transfer law in the process of the damage evolution of rock specimens,the damage model based on AE parameters and energy dissipation has been established.The results show:firstly,the mainly failure mode of rock specimens with bedding structure is inclined plane shear failure,with the obvious shear fracture zone.But homogeneous massive specimens are mainly featured by tensile failure and formed longitudinal fracture face,with brittle failure characteristics.And the weak structure of the bedding will weaken the bearing capacity of the pillar to a certain extent.Secondly,the failure of bedding rock occurs mainly in the plastic strain stage,it corresponds to AE violent period.Its axial loads are in the 60％ σc-σc range and its failure time is within the range from the 63％ tc to tc.The period for failure prediction of homogeneous massive rock should focus on before and after the yield point.The trend of dissipation of the strain in this interval is slowly decreasing (before the yield point c) → rising (after the yield point c) → sudden increase (failure point d).Thirdly,the damage model based on parameters of AE and energy dissipation is verified through real data computation and experiments,which shows that the average deviation rate of bedding rock is 8.2％ and 9.5％ and to homogeneous massive rock is 18.4％ and 19.3％.%层理构造普遍存在于煤矿地下矿柱岩体中,对其稳定性造成一定的威胁.通过含层理及均质岩石试件单轴压缩实验和CT层析扫描测试,分析了含层理岩石破坏特征,损伤演化过程中的声发射参数特征、能量耗散与传递规律,根据改进后的Duncan模型建立基于声发射、能量耗散参数的单轴损伤破坏模型.结果表明:均质岩石试件整体失稳的主要原因为纵向拉伸破坏,含层理试件宏观主裂纹为单一剪切破坏形式,具有明显的剪切破碎带,层理的软弱结构面会在一定程度上削弱矿柱的承载能力;含层理构造岩石试件失稳破坏主要发生在塑性变形阶段(cd),对应于AE剧烈期,耗散应变能出现明显的起伏波动,轴向荷载60％σc～σc区间内,63％tc～tc时间阶段内;而均质岩石试件的失稳性破坏预测的重点在屈服点前后时间区间内,该区间内耗散应变能的趋势为缓慢下降(屈服点c前)→上升(屈服点c后)→骤增(破坏点d).建立基于声发射和能量耗散参数的单轴损伤破坏模型,对于含层理试件理论计算结果与试验结果平均偏差率分别为8.2％和9.5％;均质试件的理论计算结果与试验结果平均偏差率分别为18.4％和19.3％.