石墨矿石品位对其动力学特性的影响研究

Study on Effect of Graphite Ore Grade on its Dynamic Mechanical Properties

为探究石墨矿石品位与其动力学特性关联,揭示石墨矿石品位对岩石动力学特性的影响规律,选取1.57%、5.19%、10.79%、12.65%和19.50%五种品位的石墨矿石试样开展等幅冲击荷载作用下的SHPB试验研究,分析试样峰值强度(σ_(d))、动弹性模量(E_(d))、峰值应变(ε_(d))以及能耗密度(A_(SE))随石墨矿石品位的变化规律。研究结果表明:不同品位石墨矿石动力学特性的改变是石墨矿石矿物组成和石墨鳞片嵌布特征变化共同作用的结果;随着石墨矿石品位的增加,试样动力学特性发生了明显弱化,但弱化程度存在限度,具体表现为:σ_(d)、E_(d)和A_(SE)与石墨矿石品位之间存在良好的负指数型函数拟合关系(相关性系数R^(2)分别为0.977、0.930和0.973),三者均随石墨矿石品位的增加而以愈渐平缓的趋势逐渐降低,并最终趋于某稳定值;ε_(d)随石墨矿石品位的增加表现为初期近似线性增加,品位达到12.65%时出现明显跃增,之后开始缓慢减小的阶段性特征,但ε_(d)减小的程度很小,总体上可认为ε_(d)随石墨矿石品位增加仍呈现较好的弱幂函数递增规律(R^(2)为0.810),说明试样动力学特性随石墨矿石品位增加而弱化的总体趋势并未改变。

In order to reveal the influence law of graphite ore grade on its dynamic mechanical properties,SHPB tests were carried out on graphite ore samples with five grades of 1.57%,5.19%,10.79%,12.65%and 19.50%under the action of constant amplitude impact loads.Based on the analysis of microscopic fabric characteristics of the graphite ore,the peak strength(σ_(d)),dynamic elastic modulus(E_(d)),peak strain(ε_(d))and energy consumption density(A_(SE))of the samples were analyzed.The results show that the change of the dynamic mechanical properties of the graphite ores with different grades is the result of the change of mineral composition and graphite flake distribution characteristics.With the increase of graphite ore grade,the dynamic mechanical properties of the sample are obviously weakened,but there is a limit of the weakening degree.Theσ_(d),E_(d),and A_(SE)have a good negative exponential function fitting relationship with graphite grade(correlation coefficients R^(2) is 0.977,0.930 and 0.973,respectively).With the increase of graphite ore grade,theσ_(d),E_(d),and A_(SE)decrease gradually in a gentle trend and eventually reach a stable value.However,with the increase of graphite ore grade,theε_(d)increases approximately linearly at the initial stage.When the grade reaches 12.65%,theε_(d)increases significantly,and then decreases slowly,but the decrease degree ofε_(d)is very small.On the whole,it still shows a good increasing law of weak power function(R^(2) is 0.810)forε_(d)with the increase of graphite ore grade,indicating that the general weakening trend of the dynamic mechanical properties of the samples with the increase of graphite ore grade has not changed.