The evolution characteristics of rock fracturing in presplit blasts are generally affected by in situ stress resulting from tectonic forces in the Earth’s crust and from gravity. In this study, rock fracturing under coupled static stress and presplit blasting conditions is comprehensively investigated by combining experimental, theoretical and numerical methods. Model tests of two-borehole presplitting on 200 × 200 × 50 mm granite samples are carried out using a biaxial hydrostatic loading system, and blast-induced rock fracture is identified using high-speed digital image correlation. The postblast granite samples are further image processed using ImageJ to show the detailed rock fragmentation and fracture networks. The rock fracturing behaviours and fractal characteristics in presplitting under various biaxial and uniaxial stresses, and under constant uniaxial stress with different β values (angle between the orientation of uniaxial stress and the line connecting blastholes), are examined. Blast tests show that the number and length of blast-created fractures in presplitting decrease with increasing static stress, and thus, presplit crack formation gradually fails, producing a rock crack pattern with relatively low fractal dimension and fractal damage levels. Moreover, the formation of crack coalescence fails between presplit holes, and the damage to the remaining rock significantly increases when β is larger than 15°. Then, the variations in crack patterns in recent presplitting tests are analysed based on elastic mechanics by calculating the transmission and superimposition of detonation stress waves and the static stress distribution near presplit holes. Later, after performing numerical verification, the rock fracturing processes in presplitting are numerically modelled in LS-DYNA. The influences of boundary conditions on presplitting test results and the implications of the recent findings for practical presplitting are discussed accordingly.

预裂爆炸中岩石破裂的演化特征一般受到地壳构造力和重力产生的地应力的影响。在这项研究中，结合实验、理论和数值方法，对静应力耦合和预裂爆破条件下的岩石破裂进行了全面研究。利用双轴静水压加载系统对200×200×50 mm花岗岩样品进行两孔预裂模型试验，并利用高速数字图像相关识别爆炸引起的岩石破裂。使用 ImageJ 对爆破后的花岗岩样本进行进一步图像处理，以显示详细的岩石破碎和断裂网络。研究了在各种双轴和单轴应力以及不同β值（单轴应力方向与炮孔连接线之间的角度）的恒定单轴应力下预裂时岩石的破裂行为和分形特征。爆炸试验表明，随着静应力的增加，预裂中爆炸产生的裂缝数量和长度减少，因此预裂裂纹的形成逐渐失败，产生分形维数和分形损伤水平相对较低的岩石裂纹模式。而且，当β大于15°时，预裂孔之间的裂纹聚合失败，对剩余岩石的损伤显着增加。然后，基于弹性力学，通过计算爆轰应力波的传递和叠加以及预裂孔附近的静应力分布，分析了近年来预裂试验中裂纹形态的变化。随后，经过数值验证，在LS-DYNA中对预裂过程中的岩石破裂过程进行了数值模拟。相应地讨论了边界条件对预裂测试结果的影响以及最新研究结果对实际预裂的影响。