The macroscopic deformation process of rock is the external performance of microscopic damage in essence, and research from the macro and micro perspectives can effectively reveal the failure mechanism of rock. To further investigate the fracture behaviors of yellow sandstone disc specimens under different loading rates, seven groups of Brazilian disc splitting tests with different loading rates from 1 × 10^–6 to 1 × 10^–4 s^–1 were carried out. A systematical investigation of loading rate effect on macroscopic mechanical responses and microscopic damage characteristics has been conducted from the stress–strain relationship obtained from material testing system, from damage three-dimensional localization based on acoustic emission techniques, and from fracture morphology by scanning electron microscope. In addition to laboratory experiment, parallel bond models of different grain size distribution indexes based on particle flow code were established. The coupling effect of loading rate and grain size distribution index was further analyzed. The results interpret that the effect of loading rate on rock fracture behaviors is determined by the process of crack initiation, propagation and coalescence, and it is also affected by distribution of different size grains. The differences of rock fracture behaviors under different loading rates were discussed from the mechanism of energy input and dissipation. The research have actual significance for stability design and evaluation of rock excavation engineering.

岩石的宏观变形过程本质上是微观损伤的外部表现，从宏观和微观的角度进行研究可以有效揭示岩石的破坏机理。为了进一步研究黄色砂岩圆盘试样在不同加载速率下的断裂行为，七组巴西圆盘劈裂试验的加载速率从1×10 ^–6到1×10 ^–4  s ^–1被执行。从材料测试系统获得的应力-应变关系，基于声发射技术的损伤三维定位以及通过扫描电子显微镜观察的断裂形态，系统地研究了加载速率对宏观力学响应和微观损伤特性的影响。 。除了实验室实验，还建立了基于颗粒流代码的不同粒度分布指标的平行键模型。进一步分析了加载速率与晶粒尺寸分布指数的耦合效应。结果表明，加载速率对岩石断裂行为的影响取决于裂纹的萌生，扩展和聚结过程，并且还受不同粒度晶粒分布的影响。从能量输入和耗散机理探讨了不同加载速率下岩石断裂行为的差异。该研究对岩石开挖工程的稳定性设计和评价具有实际意义。