A split Hopkinson pressure bar was used to perform a dynamic impact test on three different types of composite rock samples with different strength ratios.This test was conducted in order to guarantee the construction efficiency and engineering safety of composite strata,as well as to demonstrate the mechanical characteristics of composite strata under dynamic loading.The impact of strength ratio,strain rate,and incident angle on the fragmentation degree and energy consumption characteristics of composite rock samples were studied using the fractal theory of fragmentation.The test results show as follows.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 energy is absorbed by the specimen.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°,composite rock samples with a strength ratio of 1.5 have the largest fractal dimension.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,the more broken the sample is,that is,the fractal dimension of the composite rock sample is positively correlated with the energy density.
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