To overcome the problems of poor cutting effects in hard rock roadways, a cut blasting technique with large diameter charges was developed; that is, the cut holes employ 50 mm diameter blast holes and 45 mm diameter explosive sticks, while the other holes adopt 42 mm diameter blast holes and 35 mm diameter explosive sticks. First, the effect of charge diameter on damage range and cut cavity formation was analyzed. Next, simulation of wedge cut for different charge diameters was conducted to reveal the stress wave developments and compare the stress field intensities. Finally, field tests were conducted to verify the viability of this technique. The results indicate that large diameter charges can increase the damage range around cut holes to improve the fragmentation degree of the rock mass in the cut cavity and significantly enhance the cavity formation power to better expel the rock mass fragments. The stress wave evolution of wedge cut was visualized using numerical simulations, which confirmed that the use of large diameter charges in cut holes increases the stress field intensity in the cut cavity and hence increases the damage degree of the rock mass. In this study, the use of a large diameter charge for cut blasting increased the average footage by 0.30 m, and the average utilization rate of blast holes increased by 12.5%. Therefore, the cutting effects in hard rock roadways can be improved by using large diameter charges, which increase the blasting footage and the utilization rate of blast holes.

中文翻译：

---

硬岩巷道大口径装药爆破研究

为了克服硬岩巷道切割效果差的问题，开发了大直径装药的切割爆破技术。也就是说，切割孔使用直径为50毫米的爆破孔和直径为45毫米的炸药，而其他孔使用直径为42毫米的爆破孔和直径为35毫米的炸药。首先，分析了装药直径对损伤范围和切口腔形成的影响。接下来，对不同装料直径的楔形切割进行了仿真，以揭示应力波的发展并比较应力场强度。最后，进行现场测试以验证该技术的可行性。结果表明，大直径装药可以增加切孔周围的破坏范围，改善切孔内岩体的破碎程度，显着提高腔体形成能力，更好地驱赶岩体碎片。楔形切口的应力波演化通过数值模拟得到了可视化，这证实了在切孔中使用大直径装药会增加切孔中的应力场强度，从而增加岩体的破坏程度。在这项研究中，使用大直径装药进行切割爆破可将平均英尺长度增加0.30 m，爆破孔的平均利用率将提高12.5％。因此，通过使用大直径炸药，可以改善硬岩巷道的切割效果，