一维静载及循环冲击共同作用下矽卡岩力学特性试验研究

Experimental study of mechanical characteristics of skarn under one-dimensional coupled static and cyclic impact loads

利用改进的基于SHPB装置的岩石动静组合加载试验系统,对取自冬瓜山铜矿井下900 m深处的矽卡岩岩样进行一维静载及循环冲击共同作用下的加载试验。研究结果表明:在一维静载与循环冲击共同作用下,岩石具有疲劳损伤特性;预加载轴压不同,变形特征也不同,岩石应力-应变曲线呈现回弹、不回弹2种特性;随着循环冲击数增加,动态峰值应力及定义的动态变形模量减小,动态峰值应变却增大;累计冲击数与轴压呈一元二阶多项式关系;同时还表明"岩爆"的发生是动力扰动诱发岩石内部弹性能突然释放的结果;预加轴压影响岩石出现拉伸破坏或剪切破坏的效果,也影响岩石破坏块度及在动态扰动情况下发生的"岩爆"概率。

By means of the test system of rock coupled static and dynamic loads based on improved Split Hopkinson Pressure Bar (SHPB), the experiment with skarn under one-dimensional coupled static and cyclic impact loads from Dongguashan copper Mine underground 900 m in depth was carried out, and the test results were analysed. The results show that the damage of rock under one-dimensional coupled static and cyclic impact loads has fatigue characteristic. When the axial precompression stress is different, the deformational characteristics of rock are different, and stress-strain curves present two kinds of features: springback or no springback. With the increase of the amount of cyclic impact, the dynamic peak stress and defined dynamic deformation modulus decreases, but dynamic peak strain increases. The variation relationship between accumulated amount of cyclic impact with axial precompression stress is a yuan quadratic polynomial relation. Dynamic disturbance induces sudden release of elastic energy in rock interior which makes rock burst occur. The axial precompression stress has influence on the effect that rock appears tensile failure or shear failure, and it also has influence on the size of the blocks of rock failure and the probability of rock burst under dynamic disturbance.