Directional splitting mechanism of rock based on shaped charge jet
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摘要: 基于岩石材料脆性断裂模型分析,从提高炸药能量向岩石断裂表面能转换效率的角度,提出采用预切槽和多点聚能射流冲击岩石进行裂纹引导与扩展,实现岩石定向劈裂。设计了一种可用于岩石劈裂的聚能装药,利用数值计算方法研究了岩石类脆性材料在聚能射流冲击作用下的定向劈裂机制,并计算比较了不同形状金属杆射流对岩体的冲击劈裂效果。分析计算该聚能装药射流形成与岩石的侵彻断裂过程,得出用于岩石劈裂的最佳聚能装药结构与炸高。实验成功用2枚聚能装药将岩石试块按预制方向劈裂,测试获得的岩石表面应力峰值约0.5~0.8 MPa。结果表明,采用该聚能装药在25 mm炸高下能够形成长径比约1∶3的楔形金属杆射流,沿着控界面预先设计的切槽方向,多点设置聚能装药,同时起爆后形成楔形金属杆射流冲击岩石,产生了较好的定向劈裂效果。该方法将爆炸能量精准导入控界面并有效地转换成岩石断裂表面能,从而提升了岩石定向劈裂的效果及炸药的能量利用率,研究结果可为大范围岩体开挖精确控界爆破切割装置设计及降低工程爆破危害提供参考。Abstract: Based on the brittle fracture model of rock materials, from the perspective of improving the conversion efficiency of explosive energy to the fracture surface energy of rock materials, it is proposed to use pre-cutting and multi-point shaped charge jet impact on rocks for crack fracturing and propagation, achieving directional rock splitting. A shaped charge that can be used for rock splitting was designed, while the directional splitting mechanism of rock-like brittle materials under the impact of shaped charge jet is studied using numerical method, by which the impact splitting effects of different shapes of high-speed metal rods on rocks are calculated and compared. The formation of the shaped charge jet and the impact fracture process on the rock are analyzed by using numerical simulation, and the optimal shaped charge structure and explosion height for splitting are obtained. In the experiment, 2 shaped charges were used to successfully split the rock samples followed the design direction, and the peak stress on the rock surface obtained from the test were about 0.5−0.8 MPa. The results show that using this shaped charge can form a wedge-shaped metal rod with a length-to-diameter ratio of about 1∶3 at an explosion offset of 25 mm. The shaped charges are set at multiple points along the pre-cutting direction of the designed rock control interface, and at the same time, the wedge-shaped metal rod jets are formed after explosion, which impact the rock and produce a good directional splitting effect. This technology accurately introduces explosive energy into the control interface and converts it into rock fracture surface energy effectively, thereby improving the effective utilization rate of explosives, providing reference for the design of precise control blasting cutting devices for large-scale rock excavation and reducing blasting hazards.
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表 1 金属楔形杆的尺寸
Table 1. Dimensions of metal wedges
楔形杆 长度/mm 头部直径/mm 尾部直径/mm A 29.0 2 8.0 B 20.8 2 9.8 C 16.4 2 11.2 表 2 高压冲击状态方程参数
Table 2. Shock EOS parameters
材料 c0/$({\text{m} } \cdot { {\text{s} }^{ {{ - 1} } } })$ S Γ 岩石 3340 1.500 2.0 紫铜 3958 1.497 2.0 -
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