动态冲击下锦屏大理岩力学响应与能量特性

Mechanical responses and energy characteristics of the Jinping marble under the dynamic impact

为了分析锦屏水电站大理岩的动力学响应和能量特性,采用分离式霍普金森压杆对岩样开展了动态压缩试验,并引入分形维数定量表征试样的破碎形态、能耗特性及其与应变率的内在关系。结果表明:动态载荷下大理岩应力-应变曲线初始压密段不明显,当应变率较低时,应力-应变曲线呈现出回弹现象;试样峰值应力随应变率的增大而增加,且动态抗压强度与应变率对数呈线性关系;试样能量时程曲线呈“S”型演化,入射能、反射能及透射能均随应变率的增高而增大,动态抗压强度与能耗密度呈对数增长关系;随着比能量耗散值或应变率的增加,试样破坏程度和分形维数均逐渐增大。本文研究对提高爆破等动态荷载下岩石损伤破坏机理的认知具有一定参考价值。

To study the dynamic responses and energy characteristics of the marble from the Jinping hydropower station,the dynamic compression tests on the rock samples are carried out using the split-Hopkinson pressure bar,and the fractal dimension of the fragments is also introduced to quantitatively characterize the relationship among the failure shape,energy consumption characteristics and strain rate of the rock samples.The results show that the initial compaction section of the stress-strain curve of the marble under dynamic loading is not obvious,and the stress-strain curve takes on a rebound phenomenon when the strain rate is low,and the peak stress of the sample increases with the rise of strain rate.The dynamic compressive strength has a linear relationship with the logarithm of strain rate,and the energy time-history curves show an"S"-shaped evolution.The incident energy,reflected energy and transmitted energy all increase with the increasing strain rate.The dynamic compressive strength has a logarithmic growth with the energy consumption density.As the energy consumption density or strain rate rises,the failure degree and the fractal dimension of the samples gradually increase.This study is of certain reference value for improving the cognition of rock damage and fracture evolution mechanism under dynamic loads such as blast.