不同固定碳含量石墨矿石单轴压缩力学行为及损伤本构关系研究

Mechanical Behavior and Damage Constitutive Relationship of Graphite Ores with Different Fixed Carbon Content under Uniaxial Compression

不同固定碳含量石墨矿石力学性能和工业价值有所差异,研究石墨矿石力学性能与其固定碳含量之间的关系,对于深刻认识和科学利用石墨矿石具有重要意义。为此,综合运用石墨化学分析方法、岩石单轴压缩试验和岩石统计损伤理论,研究不同固定碳含量石墨矿石单轴压缩荷载作用下的力学响应特性,揭示固定碳含量对石墨矿石力学性质及损伤本构关系的影响。试验结果表明:石墨矿石试样单轴抗压强度随固定碳含量增加呈负指数型函数递减趋势、弹性模量呈线性函数递减趋势、峰值应变呈指数型函数递增趋势;随固定碳含量增加,石墨矿石试样破坏模式由张拉破坏过渡到拉剪混合破坏,最后向剪切破坏转变。引入与固定碳含量相关的损伤因子,建立了反映固定碳含量影响的石墨矿石统计强度型损伤本构模型,并将理论曲线与试验曲线进行对比,验证了所建立的损伤本构模型的有效性与合理性。

The mechanical properties and industrial value of graphite ores with different fixed carbon content are different. The study on the relationship between mechanical properties of graphite ores and fixed carbon content is of great significance for deep understanding and scientific utilization of graphite ores. Therefore,the mechanical response characteristics of graphite ores with different fixed carbon content under uniaxial compression load were studied by using graphite chemical analysis method,rock uniaxial compression test and statistical damage theory,and the influence of fixed carbon content on mechanical properties and damage constitutive relationship of graphite ore was revealed. The results show that the uniaxial compressive strength of graphite ore specimens decreases with the increase of fixed carbon content in a negative exponential function,the elastic modulus decreases with a linear function,and the peak strain increases with an exponential function. And,with the increase of fixed carbon content,the failure mode of graphite ore specimens changes from tensile failure to tension-shear mixed failure and finally to shear failure. On this basis,the damage factor related to fixed carbon content was introduced to establish the statistical strength damage constitutive model of graphite ore reflecting the influence of fixed carbon content. The theoretical curves were compared with the experimental curves,which verified the validity and rationality of the established damage constitutive model.