节理千枚岩动力学特性研究

Study on the Dynamic Characteristics of Jointed Phyllite

为探究千枚岩节理面对其动力学特性的影响,选取不同节理倾角及方位角的千枚岩岩样进行霍普金森杆(SHPB)试验,研究发现:对于动态单轴冲击试验,随着冲击速度的提高,各个节理倾角的千枚岩应力-应变曲线线形趋于一致,延性不断增强,动态抗压峰值强度整体得到提高;随着节理面倾角的增加,千枚岩动态单轴抗压强度先减小后增加,呈“U”型分布规律,β=45°或60°时动态单轴抗压强度最小;随着节理倾角的增加,千枚岩的动弹性模量以V=18.880 m/s为界,出现较大的离散;对于动态单轴压缩试验,随着冲击速度的增大千枚岩各向异性度(AD)呈现线性增大的变化规律;对于动态巴西劈裂试验,α=15°、30°、45°时,岩石应力快速增长,达到峰值强度后,岩样发生脆性破坏,当α为其他方位角角度的情况下,岩石应力增长较为平缓,岩样发生塑性破坏,且脆性破坏的峰值强度显著大于塑性破坏的峰值强度;千枚岩动态抗拉峰值强度先增长后减小,其中α=30°时动态抗拉峰值强度最大;千枚岩拉伸动弹性模量随着冲击速度提高总体提高;方位角不同,岩样的破坏模式也有所不同,随着α的增大,岩样破坏模式逐渐由沿节理面张拉破坏为主的模式转化为以垂直于节理面的张拉破坏为主的模式。

In order to explore the influence of phyllite joints on its dynamic characteristics,phyllite samples with different joint dips and azimuth angles were selected for Hopkinson bar(SHPB)test.The study shows that:with the increase of the impact velocity,the phyllite stress-strain curve of each joint surface inclination tends to be consistent,the ductility continues to increase,and the dynamic compressive peak strength is improved as a whole in dynamic uniaxial impact test.With the increase of the joint surface inclination,the dynamic uniaxial compressive strength of the phyllite decreases firstly and then increases,showing a“U”-shaped distribution.The dynamic uniaxial compressive strength is the smallest whenβ=45°or 60°.With the increase of the joint dip,the dynamic elastic modulus of phyllite is bounded by V=18.880 m/s,showing a large dispersion.The anisotropy(AD)of phyllite increases linearly with the increase of the impact velocity in dynamic uniaxial impact test.For the dynamic Brazilian split test,whenα=15°,30°,45°,the rock stress increases rapidly,and the rock sample undergoes brittle failure after reaching the peak strength.In the case of other azimuth anglesα,the stress growth of the rock is relatively gentle,and the rock sample undergoes plastic failure.The peak strength of brittle failure is significantly greater than the peak strength of plastic failure.The dynamic tensile peak strength of phyllite increases firstly and then decreases,and the dynamic tensile peak strength is the largest whenα=30°.With the increase of the impact velocity,the tensile dynamic elastic modulus of phyllite increase overall.The azimuth angle is different,the failure mode of the rock sample is also different.With the increase ofα,the failure mode of the rock sample gradually transforms from the tensile failure along the joint plane to tension failure perpendicular to the joint plane.