Saturated rocks, widely existing in various deep underground engineering, are likely to be encountered coupled static-dynamic loading. It is thus vital to acquire the combined effect of water saturation and static pre-tension on the dynamic tensile strength, and establish a reasonable crack extension model for describing the fracturing mechanism of saturated rocks under coupled static-dynamic tension. In this study, from the perspective of meso-mechanics, the relationship between pore water pressure and static pre-tension loading are first deduced, and then the analytic solution of stress field of elliptical crack orifice under coupled pore water pressure and far-field stress is solved using complex function. The effect of pore water pressure is considered into Griffith theory, and the most dangerous fracture azimuth angle of elliptical crack in rocks under combined far-field stress and pore water pressure are determined. Second, the length of fracture process zone of initial crack in saturated rocks under static pre-loading is estimated based on Schmidt's maximum tensile stress criterion. Finally, a wing-crack extension model is proposed to analyze the dynamic fracturing behavior of saturated rocks under pre-tension, and the theoretical calculation formula for tensile strength of saturated rocks under combined static-dynamic loading is obtained. To validate this new model, nine coupled static-dynamic tension tests with different pre-static loading ratio are performed on saturated flattened Brazilian disc (FBD) specimens, in virtue of the split Hopkinson pressure bar (SHPB) specialized with an axial confining apparatus. A rational consistency is observed between the experimental and theoretical results in terms of the dynamic tensile strength of saturated rocks.

饱和岩体广泛存在于各种深部地下工程中，容易遇到静-动力耦合加载。因此，掌握含水饱和度和静预应力对动抗拉强度的综合影响，建立合理的裂缝扩展模型来描述静动耦合作用下饱和岩体的压裂机理至关重要。本研究首先从细观力学的角度推导了孔隙水压力与静预紧载荷的关系，然后在耦合孔隙水压力和远场应力作用下椭圆裂缝孔口应力场的解析解使用复函数求解。格里菲斯理论考虑孔隙水压力的影响,确定了远场应力和孔隙水压力组合作用下岩石椭圆裂缝最危险的断裂方位角。其次，基于施密特最大拉应力准则估算了静态预加载下饱和岩体初始裂纹的断裂过程带长度。最后，提出了翼缝扩展模型，分析了饱和岩在预应力作用下的动态破裂行为，得到了静动力联合加载下饱和岩抗拉强度的理论计算公式。为了验证这个新模型，在饱和扁平巴西圆盘 (FBD) 试样上进行了九个具有不同预静载荷比的静态-动态拉伸试验。分体式霍普金森压力杆 (SHPB) 专门用于轴向约束装置。就饱和岩石的动态抗拉强度而言，实验结果与理论结果之间存在合理的一致性。