静动态压缩下千枚岩长径比效应影响研究

为了研究长径比效应对层状千枚岩力学特性、能量耗散及破坏模式的影响,文中选用4种倾角（α=0°、30°、60°、90°）下不同长径比（L/D=0.5、0.6、0.8、1.0、1.2、1.6、2.0）的千枚岩分别进行了静载单轴压缩和分离式霍普金森杆（SHPB）试验。结果发现,静载压缩试验条件下,不同倾角下千枚岩随长径比的增大,峰值强度和峰值应变均减小。通过单轴动态压缩试验,发现4种层理倾角千枚岩动态抗压强度与试样长径比呈二次函数关系,随着长径比的增加,动态抗压强度出现一个峰值后逐渐降低;千枚岩峰值应变与试样长径比呈指数函数关系下降;对动态冲击压缩试验进行能量分析,发现不同工况的千枚岩在同一冲击气压下,入射能、反射能、透射能均呈现出先缓慢上升再快速上升最后趋于稳定的三段式变化;随着试样长径比增大,千枚岩反射能比先增大后减小,透射能比先减小后增大;采用能量比值法进行对比分析,发现在长径比L/D=1.2时,千枚岩的反射能比达到最大,透射能比达到最小;对千枚岩的宏观破坏模式进行分析,发现动态冲击压缩下千枚岩的宏观破坏模式受长径比影响较大,长径比越小破坏越完全;长径比越大,破坏越不充分。

Influence of phyllite aspect ratio under static and dynamic compression

This study investigates the influence of aspect ratio on the mechanical properties, energy dissipation, and failure mode of layered phyllite. Uniaxial compression and split Hopkinson pressure bar (SHPB) tests were conducted on phyllite specimens with varying aspect ratios (L/D=0.5,0.6,0.8,1.0,1.2,1.6,2.0) at four inclination angles(α=0°,30°,60°,90°). Results from static uniaxial compression test reveal that the peak strength and the peak strain of phyllite decrease with increasing aspect ratio at different dip angles. Uniaxial dynamic compression tests show that the dynamic compressive strength of phyllite with four bedding dip angles exhibits a quadratic function relationship with the length-diameter ratio of the specimen under dynamic impact compression conditions. With increasing length-diameter ratio, the dynamic compressive strength reaches a peak and then gradually decreases. The peak strain of phyllite decreases exponentially with the aspect ratio of specimen. Energy analysis of dynamic impact compression test indicates a three-stage change in incident energy, reflection energy, and transmission energy of phyllite under different working conditions, from slow rise to rapid rise and finally to being stable. The reflection energy ratio of phyllite increases first and then decreases with the increase of the length-diameter ratio, while the transmission energy ratio shows the opposite trend. Comparative analysis using the energy ratio method reveals that the reflection energy ratio of phyllite reaches its maximum and the transmission energy ratio reaches its minimum when the aspect ratio is L/D=1.2. Macroscopic failure mode analysis indicates that the aspect ratio significantly affects the macroscopic failure mode of phyllite under dynamic impact compression, with smaller the aspect ratios resulting in more complete fractures and larger aspect ratios leading to less sufficient damage.