Widely existing in many fields of geotechnical engineering practices, rocks inherently containing pre-existing flaws frequently suffer from static pre-compression and dynamic disturbance as the same time. Understanding the mechanical properties and fracturing behaviors of flawed rocks under combined static-dynamic loading is of great importance for rock engineering applications. In this work, pre-flawed rocks are compressed under uniaxial combined static-dynamic loading using the modified split Hopkinson pressure bar (SHPB) system. The influences of flaw intensity and pre-stress on dynamic mechanical responses and progressive fracturing behaviors of pre-flawed rocks are systematically investigated. Experimental results indicate that the dynamic deformation modulus of rocks is not rate-dependent, while the dynamic strength and total strength perform evident rate-dependence. With increasing flaw intensity, the dynamic strength, total strength and deformation modulus show a decease tendency. With increasing pre-stress ratio, the dynamic strength deceases while the deformation modulus increases, and the total strength increases first before pre-stress ratio of 0.6 and then slightly deceases. Progressive fracturing behaviors are comprehensively analyzed by virtue of high-speed camera and digital image correlation (DIC) analysis. With increasing flaw intensity, more mixed cracks are initiated on specimen surface and the crack networks become more complex. With increasing pre-stress ratio, tensile-shear mixed cracks relatively increase while compression-shear mixed cracks relatively decrease. Generally, pre-flawed rock specimens failed into compression-shear mixed failure patterns. Fragmentation analysis shows that rock specimens are more fragmented under higher strain rate. The mean fragment size and fractal dimension generally increases with increasing flaw intensity. With increasing pre-stress ratio, the mean fragment size values perform “decrease-increase” tendency while the fractal dimension values perform “increase-decrease” tendency, with the turning point around 0.6.

岩土工程实践中广泛存在的固有缺陷岩石，往往同时受到静态预压缩和动态扰动的影响。了解有裂隙岩石在静动力联合载荷下的力学特性和破裂行为对于岩石工程应用具有重要意义。在这项工作中，使用改进的分离式霍普金森压力杆 (SHPB) 系统在单轴组合静-动力载荷下压缩预裂岩石。系统研究了裂纹强度和预应力对预裂纹岩石动态力学响应和渐进压裂行为的影响。实验结果表明，岩石的动态变形模量与速率无关，而动态强度和总强度表现出明显的速率依赖性。随着缺陷强度的增加，动态强度、总强度和变形模量均呈下降趋势。随着预应力比的增加，动强度降低，变形模量增加，总强度在预应力比为0.6之前先增加，然后略有下降。借助高速相机和数字图像相关（DIC）分析，对渐进压裂行为进行综合分析。随着裂纹强度的增加，试样表面产生更多的混合裂纹，裂纹网络变得更加复杂。随着预应力比的增大，拉剪混合裂纹相对增多，压剪混合裂纹相对减少。一般来说，预裂的岩石试样失败为压缩-剪切混合破坏模式。碎裂分析表明，岩石试样在较高应变率下更易碎裂。平均碎片大小和分形维数通常随着缺陷强度的增加而增加。随着预应力比的增大，平均碎片尺寸值呈“减小-增大”趋势，而分形维数值呈“增大-减小”趋势，拐点在0.6左右。