冲击载荷下石墨矿石动力学特性的层理效应及宏微观破坏机理  

Bedding effect and macro-micro mechanism of graphite ore dynamic mechanical properties under impact loads

作　　者：叶海旺[1,2] 钱正昆 雷涛[1,2] 温颖[3] 李睿 YE Haiwang;QIAN Zhengkun;LEI Tao;WEN Ying;LI Rui(School of Resources and Environment Engineering,Wuhan University of Technology,Wuhan 430070,Hubei,China;Hubei Key Laboratory of Mineral Resources Processing and Environment,Wuhan University of Technology,Wuhan 430070,Hubei,China;Hubei Geological&Mining Exploration Co.,Ltd.,Wuhan 430070,Hubei,China)

机构地区：[1]武汉理工大学资源与环境工程学院,湖北武汉430070 [2]武汉理工大学矿物资源加工与环境湖北省重点实验室,湖北武汉430070 [3]湖北省地质矿业开发有限责任公司,湖北武汉430070

出　　处：《爆炸与冲击》2023年第12期25-37,共13页Explosion and Shock Waves

基　　金：国家重点研发计划(2020YFC1909602,2021YFC2902901);湖北省重点研发计划(2021BCA152)。

摘　　要：为探究冲击荷载作用下层理对石墨矿石动力学特性的影响规律,采用直径为50 mm的分离式霍普金森压杆(split Hopkinson pressure bar, SHPB)系统,对0°、 45°和90°层理角度的石墨矿石开展了不同冲击荷载(0.3、 0.4和0.5 MPa)下的动态压缩实验,并结合高速摄影和电子扫描技术分析了不同层理角度石墨矿石的动态力学特性和冲击破坏模式。研究结果表明:石墨矿石中矿物多呈同形粒状定向排列,接触界限不规则,白云母和石英含量较高,与石墨伴生,沿层理面富集;层理面的存在对石墨矿石的力学性质存在劣化作用,45°层理劣化作用最强;能耗特性随层理角度增大呈U形变化,与强度特征相似;同一应变率下,矿石破碎尺寸与能耗密度具有明显的相关性,0°层理破碎平均尺寸较小,能耗密度较大,45°层理破碎后块度最大,能耗密度最小;受外力作用时,石墨鳞片不仅从内部断裂,也易被伴生矿物撕裂,随层理角度的增大,试样破坏形式可归纳为张拉破坏—剪切破坏—张拉劈裂破坏的演化过程。冲击荷载作用下,石墨鳞片破坏程度主要受压力大小和作用方向控制,拉伸破坏可减少石墨鳞片内部断裂,低应变率可减少岩粉产生。因此,可通过调整冲击波传播方向、降低峰值应力和增大矿石拉应力破坏区域,以减少爆破冲击对石墨鳞片的破坏作用。To reveal the influence law of graphite ore with different bedding angles under impact load,impact experiments on graphite ore samples with different bedding angles(0°,45°and 90°)were conducted by using a 50 mm diameter split Hopkinson pressure bar(SHPB)device,with the combined use of high-speed photography and electron microscopy scan.The dynamic mechanical properties and impact failure modes were investigated during the dynamic fracture process.The results show that most of the minerals in graphite ore are arranged in an allotriomorphic granular orientation within an irregular contact boundary.There is a high content of muscovite and quartz,associated with graphite and enriched along the bedding planes.The bedding angles have a deterioration effect on samples,and the 45°bedding angle has the strongest deterioration effect.The energy dissipation characteristics show a U-shaped trend with the increase of bedding angle,similar to the strength characteristics.At the same strain rate,the average particle size of the broken samples is strongly correlated with the energy dissipation density.The average particle size of 0°bedding angle is the smallest,with the largest energy dissipation density.On the contrary,the average particle size is the largest when the bedding angle is 45°,with the smallest energy dissipation density.When graphite flakes are subjected to external forces,they will not only break from the inside but also be torn by associated minerals.The destruction form can be summarized as the evolution of tensile failure-shear failure-tensile splitting failure.The relevant characteristic results obtained from the experiments show that the damage degree of the graphite flakes is mainly controlled by the magnitude and direction of the impact load.Tensile failure can reduce the internal fracture of graphite flakes,and a low strain rate can reduce the production of rock powder.Therefore,the destructive effect of blasting impact load on graphite flakes can be reduced by adjusting the propagation direction of

关 键 词：层理效应 石墨矿 分离式霍普金森压杆 动力学特性 破坏模式 

分 类 号：O347.3[理学—固体力学]