The Mechanism of Explosion Funnel Formation Considering the Dynamic and Static Time Sequential Action of Charge Blasting
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摘要: 爆破漏斗理论是爆破工程中最重要的基础性研究工作之一,深入理解爆破漏斗形成机理有助于完善爆破理论和优化爆破参数,更好指导现场作业。本研究基于改进的双指数型爆炸载荷函数及爆生气体压力状态方程,综合分析了爆炸应力波与爆生气体的加载特点,构建了考虑药包爆破动-静时序作用的爆炸载荷联合加载模型,开展了爆破漏斗离散元数值模拟,研究了被爆岩体的裂隙发育及破碎抛掷过程。结果表明:运用考虑药包爆破动-静时序作用的爆炸载荷加载模型形成的爆破漏斗尺寸与现场试验结果较为吻合,可以较好地反映被爆岩体的裂隙形成、演化与碎块的抛掷效果。爆破漏斗形成过程中,药包产生的爆炸应力波与爆生气体具有不同的破岩作用。爆炸应力波加载率大,作用时间短,引起了距爆源较近区域的微裂隙,同时在自由面处反射拉伸形成“片落”破坏;而爆生气体则是形成距爆源较远区域径向长裂隙的主要原因,同时推动破碎岩体向外抛掷。爆生气体不仅具有准静态作用,也存在一定程度的动态作用,延长了爆破振动的作用时间,加强了爆破振动的速度峰值。裂隙发育可根据其产生时序与原因大致分为爆炸应力波加载致裂、爆生气体加载致裂以及变形能释放致裂三个阶段。
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关键词:
Abstract: The theory of explosion funnel is a fundamental research work in the field of blasting engineering. A thorough understanding of the formation mechanism of the explosion funnel can contribute to enhancing the blasting theory, optimizing the blasting parameters, and providing better guidance for field operations. By utilizing an improved double-exponential type explosive load function and explosion gas pressure equation of state, this study comprehensively analyzes the loading characteristics of explosive stress wave and explosion gas. Furthermore, a joint loading model considering both kinetic and static time sequential effects of blasting was constructed. Then, discrete element numerical simulation was conducted to investigate the fracture development within the rock mass of the explosion funnel as well as examine the crushing and throwing process. The results demonstrate that the size of the blasting funnel formed by using the explosive load loading model considering the dynamic-static time-sequence effect of packet blasting is more consistent with the field test results, and it can better reflect the formation and evolution of the fracture of the rock body being blasted and the throwing effect of the fragments. During the formation of the explosion funnel, both the explosive stress wave generated by the charge and explosive gas have distinct effects on rock fragmentation. The explosive stress wave exhibits a high loading rate and acts for a short period, resulting in micro-fractures near to the explosion source. At the same time, the reflection and tension on the free surface form a "spalling fall" failure. In contrast, the blast-generated gases primarily cause long radial fractures in regions farther away from the blast source while simultaneously propelling fragmented rock mass outward for throwing. These gases not only exert quasi-static effects but also possess certain degrees of dynamic effects, prolonging the action time of blasting vibration and intensifying velocity peaks during such vibrations. Fracture development can be roughly categorized into three stages based on their time sequence and causes: fractures induced by explosive stress wave, fractures caused by explosive gas, and fractures resulting from deformation energy release.-
Key words:
- Explosion funnel /
- Explosion stress wave /
- Explosive gas /
- Fracture development /
- Crushing and throwing
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