强度比对类复合岩样冲击破碎特征的影响

为了保证复合地层中施工效率及工程安全，揭示动荷载作用下复合岩层的力学特征，通过分离式霍普金森压杆对三种不同强度比的类复合岩样进行动态巴西劈裂试验，基于破碎分形理论，探究强度比、应变率、入射角对类复合岩样的破碎程度及能耗特性的影响。试验结果表明：1）层理面倾角对类复合岩样破碎形态有较大影响，当应变率为146.36 s-1时，沿层理面加载试样易发生劈裂拉伸破坏，且强度比越低试样破坏所需吸收的能量越少；2）当入射角为0°时，类复合岩样分形维数随着强度比的增大而增大，但当入射角为90°时AC复合岩样（强度比为1.5）分形维数最大；3）类复合岩样吸收的能量主要用于裂纹扩展，单位体积内试样吸收的能量越大，试样越破碎，即类复合岩样分形维数与能耗密度呈正相关。

Influence of strength ratio on impact fracture characteristics of composite rock-like samples

In order to ensure the construction efficiency and engineering safety in composite strata and reveal the mechanical characteristics of composite strata under dynamic loading, the dynamic impact test of three kinds of composite rock samples with different strength ratios was carried out by split Hopkinson pressure bar. Based on the fractal theory of fragmentation, the effects of strength ratio, strain rate and incident angle on the fragmentation degree and energy consumption characteristics of composite rock samples were investigated. The test results show that: 1) The dip angle of the bedding plane has a great influence on the fracture morphology of the composite rock sample, when the strain rate is 146.36 s-1, the specimen loaded along the bedding plane is prone to splitting tensile failure, and the lower the strength ratio, the less the energy absorbed by the specimen. 2) When the incident angle is 0 °, the fractal dimension of the composite rock sample increases with the increase of the strength ratio, but when the incident angle is 90 °, the fractal dimension of the AC composite rock sample (strength ratio is 1.5) is the largest. 3) The energy absorbed by the composite rock sample is mainly used for crack propagation. The larger the energy absorbed by the sample per unit volume is, the more broken the sample is, that is, the fractal dimension of the composite rock sample is positively correlated with the energy density.