Influence of filled joints with different inclination angles on rock blasting fragmentation
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摘要: 节理的存在对岩石爆破效果有显著影响。通过试验与数值模拟相结合的方式研究不同节理倾角对爆破块度的影响。采用一组含有不同角度节理的混凝土模型试样开展爆破试验,在试样竖直孔中装填雷管并爆破,使用高速摄像机记录试样爆破破碎过程,观测了起爆后不同时刻节理面的动态响应,利用图像处理方法进行爆破块度提取,分析了节理倾角对爆破块度的影响,采用LS-DYNA有限元数值模拟获得应力波的传播过程以及应变场的演变过程。试验与数值计算结果表明,节理对爆破块度分布及应力波传播有显著影响,主要源于爆炸应力波在节理处的反射,这与节理的变形特性有关,随着节理倾角增大,爆破块度先减小后增大,节理中的有效应力和峰值质点振动速度(peak particle velocity /PPV)透射总体呈下降趋势,但在45°至60°之间回升,其中45°左右为爆破最有利条件。数值裂纹网络重建和图像处理结果表明,随着节理倾角的增加,试样中产生的垂直裂纹增加,水平裂纹有所减少。研究结果有助于理解节理与爆炸应力波之间的相互作用,并优化节理岩体的爆破参数。
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关键词:
Abstract: The presence of joints significantly influences the performance of rock blasting. The impact of different joint inclination on blasting fragmentation was studied through a combination of experiments and numerical simulations. In this study, a group of concrete model specimens containing joints with different angles was used to carry out blasting experiments to investigate the effect of joint inclination on blast fragmentation. During experiments, detonators were placed in vertical boreholes in the specimens and detonated, while high-speed camera was used to capture the fragmentation process. The dynamic responses of joint surfaces at different time intervals after detonation was observed, and blasting fragmentation distribution was extracted using image processing techniques. The effect of joint inclination on blasting fragmentation was analyzed. Then LS-DYNA finite element numerical simulations were developed to obtain the propagation of stress waves and the evolution of strain fields within the specimens. Experimental and numerical results indicated that the joints have a significant influence on the distribution of blasting fragmentation and the propagation of stress waves, and the impact of the joints on the blasting performance was mainly attributed to the reflection of blasting waves from the joints, which was related to the deformation characteristics of the joints. With the increase of joint inclination, the blasting fragmentation initially decreased followed by an increase. The effective stress and peak particle velocity (PPV) transmission in the joints decreased overall with the increase of joint inclination but showed a rebound between 45° and 60°, which identified approximately 45° as the most favorable condition for rock fragmentation under blasting. Moreover, the results obtained from numerical crack network reconstruction and image processing revealed that there was an upsurge in the occurrence of vertical cracks in the specimen as the joint inclination increased, while a decline was observed in the presence of horizontal cracks. These study results help in understanding the interaction between joints and blasting stresses and optimizing blasting parameters in jointed rock.-
Key words:
- blasting model experiments /
- jointed rock mass /
- stress wave /
- fragmentation distribution
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