冲击载荷作用下煤岩破碎与耗能规律实验研究

为了探索煤岩在冲击过程中的破坏特征和能量耗散规律,利用Φ75 mm霍普金森压杆(SHPB)实验装置,对煤岩试件进行不同应变率条件下的冲击压缩实验,分析了冲击加载速率对煤岩破碎耗能和块度分布的影响。实验结果表明:在实验应变率范围内,随着子弹速度的提高,应变率和应力波携带的能量均呈线性增长,而煤岩破碎耗散能则呈指数上升。通过对实验碎块进行块度分维,发现随着应变率的提高,试件的耗散能密度快速增大,煤岩碎块的分形维数就越大,块度越细,破坏的程度越剧烈。分形维数与应变率及耗散能密度之间呈对数增长的关系,即分形维数增大的趋势变缓。

Experimental research on failure and energy dissipation law of coal under impact load

In order to explore the failure characteristics and energy dissipation law of coal during the impact process, the impact compression test of coal under different strain rates has been carried out by using split-Hopkinson pressure bar (SHPB) of 75 mm in diameter.The influence of loading rate on the energy dissipation and fragment distribution has also been discussed.The experiment results have shown that, the strain rate and energy of stress wave are increasing linearly with the improvement of the bullet velocity.Meanwhile, the dissipation energy which leads to the coal broken is increasing expo-nentially with strain rate.According to the research on fractal dimension of coal fragment, it has been found that the greater the strain rate is, the larger the fractal dimension is, the smaller the fragment-size is, the more severe fragmentation is. The relationship between fractal dimension and strain rate and dis-sipated energy density is of logarithmic growth, which means the increasing trend of fractal dimension is getting slower.