冲击载荷下煤样动态拉伸劈裂能量耗散特征实验

为研究煤样动态拉伸变形破坏过程中的能量耗散规律,利用分离式霍普金森杆冲击加载系统,对煤样进行冲击条件下巴西圆盘劈裂试验,探讨了冲击速度、层理倾角及饱和含水对煤样总吸收能密度、总耗散能密度和损伤变量的影响;同时将煤样破碎后产生粒径为0~0.2 mm和0.2~5 mm的碎屑进行收集,并对不同尺寸碎屑的分布特征进行了对比分析。研究表明:同一层理倾角的自然煤样损伤变量随着冲击速度的增加呈近似线性增加,饱水煤样损伤变量整体随冲击速度增大呈指数函数增加;相比于自然煤样,饱水煤样粒径为0~0.2 mm的碎屑量减少了14.1%~31.3%,粒径为0.2~5 mm的碎屑量减少了33.7%~53.0%;但当层理倾角为45°时,饱水煤样碎屑量质量百分比反而比自然煤样要大。

Experimental study on energy dissipation characteristics of coal samples under impact loading

The energy dissipation law of coal under different impact loading conditions was experimentally investigated by using a Split Hopkinson Pressure Bar.The indirect dynamic Brazilian disc split tension tests for coals were carried out.The total absorption energy density,total dissipated energy density and damage variable for different bedding angles under different impact velocities were analyzed and discussed.Meanwhile,the post-failure fragments of coal samples (0-0.2 mm and 0.2-5 mm) were collected and quantitatively analyzed to characterize the dynamic failure features for coal samples.Based on the experimental results,it was found that the damage variable of air dry coal specimens with the same bedding angle nearly linearly increases with the increase of impact velocity,and the damage variable of overall saturated coals increases exponentially with the increase of impact velocity.Except the bedding angle of 45°,14.1% to 31.3% fragment reductions of 0-0.2 mm and 33.7% to 53.0% reductions of 0.2-5 mm were observed for the saturated coals compared to dry ones.For the bedding angle of 45°,the water saturation did not reduce fragments.