为研究干湿循环和应力率对石灰岩动态拉伸性能的影响，利用分离式霍普金森压杆（SHPB）试验系统，对不同干湿循环等级的石灰岩试样开展动态劈裂试验，结合超高速相机、数字图像相关法（DIC）以及裂纹分析工具FracPaQ，探究应力率、干湿循环作用对试样应变场演化、裂纹扩展、能量耗散以及分形维数的影响规律。研究结果表明：冲击荷载作用下，试样主应变集中域和主裂纹率先出现在试样中心并沿其径向发育，次生裂纹产生在试样与压杆的接触端，裂纹之间充分发育、交汇，贯穿形成破碎面，试样最终发生破坏；干湿循环0次试样在133.48、149.79、174.36、234.91 GPa•s-1应力率下主裂纹张开速度分别为84.67、94.83、101.50和105.67 m/s，最大主裂纹张开速度随着应力率的增加而增大；基于FracPaQ软件对试样破坏裂纹进行分析发现，在主裂纹张开早期，试样水平方向上主裂纹对应的归一化长度占主导地位，垂直方向上裂纹对应的归一化长度随着主裂纹张开宽度的增加及次生裂纹的扩展而增大；随着干湿循环次数的增加，试样次生裂纹逐渐发育，导致垂直方向上裂纹对应的归一化长度逐渐增大；石灰岩拉伸破坏过程中试样断裂轨迹长度与角度的关系符合高斯函数；随着应力率的增大，试样抗拉强度增大，导致其发生破坏时所需吸收能增加，并伴随着分形维数的增大；随着干湿循环次数的增加，岩样承载能力下降，其发生破坏时所需吸收能减小，同时分形维数明显增大。

In order to study the effects of dry-wet cycles and stress rate on the dynamic tensile properties of limestone, the dynamic splitting tests of limestone samples with different dry-wet cycles grades were carried out by using the split Hopkinson pressure bar (SHPB) test system. Combined with the ultra-high-speed camera, digital image correlation method (DIC) and crack analysis tool FracPaQ, the effects of stress rate and dry-wet cycles on the strain field evolution, crack propagation, energy dissipation and fractal dimension of the samples were investigated. The results show that under the impact load, the main strain concentration domain and the main crack of the specimen first appear in the center of the specimen and develop along its radial direction. The secondary cracks are generated at the contact end of the specimen and the compression bar. The cracks are fully developed and intersected, and the broken surface is formed through, and the specimen is finally destroyed.During the observation period, the main crack opening speeds of the samples with 0 times of dry-wet cycles under the stress rates of 133.48, 149.79, 174.36 and 234.91 GPa•s-1 were 84.67, 94.83, 101.50 and 105.67 m/s, The maximum main crack opening velocity increases with the increase of stress rate. Based on FracPaQ software, it is found that in the early stage of the main crack opening, the normalized length corresponding to the main crack in the horizontal direction of the sample is dominant, and the normalized length corresponding to the crack in the vertical direction increases with the increase of the opening width of the main crack and the expansion of the secondary crack. With the increase of the number of dry-wet cycles, the secondary cracks of the sample gradually develop, which leads to the increase of the normalized length corresponding to the cracks in the vertical direction. The relationship between the length and angle of the fracture trajectory of the specimen during the tensile failure of the limestone conforms to the Gaussian function ; as the stress rate increases, the tensile strength of the sample increases, resulting in an increase in the absorption energy required for failure, accompanied by an increase in the fractal dimension. With the increase of the number of dry-wet cycles, the bearing capacity of the rock sample decreases, the absorption energy required for its failure decreases, and the fractal dimension increases significantly.