(1. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area，Ministry of Education，China Three Gorges University，Yichang，Hubei 443002，China；2. Suihua University，Suihua，Heilongjiang 152001，China；
3. State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact，
The Army Engineering University of PLA，Nanjing，Jiangsu 210007，China)
Abstract：In order to study the dynamic progressive failure characteristics and crack propagation mechanisms of pre-fabricated flaw sandstone，the impact compression tests were conducted on sandstone specimens with pre-fabricated double flaws using the split Hopkinson pressure bar(SHPB) device. The real-time monitoring of crack propagation and dynamic failure processes was carried out using digital image correlation(DIC) technology. An analysis of the strength characteristics and failure modes under different flaw angles was performed to reveal the corresponding crack strain evolution mechanisms. The results show that：(1) the crack initiation load，determined by capturing the surface crack whitening，ranges from 70% to 83% of the peak load，with both peak and initiation loads exhibiting a“U”-shaped trend，initially decreasing and then increasing with the flaw angle. (2) The energy dissipation rate，inferred from the number of fragments，shows a significant positive correlation with the degree of fragmentation，with the lowest and highest energy dissipation rates observed in the 45° and 90° specimens，respectively. (3) During crack propagation，tensile cracks generally form prior to shear cracks. The former are distributed along the direction of the applied load，while the latter appear within an angular range of approximately 50° to 130° relative to the load direction. Specimens with different flaw angles exhibit three primary failure modes：“一”-shaped tensile splitting failure，“X”-shaped tensile-shear mixed failure，and“spindle”and“X”-shaped composite failure，involving six distinct crack aggregation forms. (4) The progressive failure process under impact loading is divided into three stages：elastic deformation，yield deformation，and macroscopic failure. The failure process is primarily determined by the strain concentration factor( ) at the crack tip and the crack initiation time. The slope mean square index(K) of the curve provides a theoretical basis for evaluating the dynamic damage rate of fractured rock masses.
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2025, Vol. 44 
