球面爆轰波下不同孔径耦合装药孔壁压力沿炮孔轴向分布特征

Characteristics of axial distribution of borehole wall pressure along the borehole of coupled charges with different borehole diameters under spherical detonation wave

摘要:

为分析岩石爆破孔壁压力沿炮孔轴向分布的特征,采用理论分析、模型试验和有限元模拟相结合的方法,对不同孔径耦合装药炮孔轴向孔壁压力进行研究。首先基于球面爆轰波理论,建立炮孔内爆轰作用模型；以爆轰波与孔壁的入射角和炮孔直径关系为基础,推导出各阶段爆轰作用下的孔壁压力理论计算公式,得到不同孔径的孔壁压力沿炮孔轴向孔壁的变化曲线。为验证理论分析的合理性,进一步利用混凝土厚壁圆筒模型试验,运用高速多路动态应变测试系统对孔壁压力进行监测,同时建立不同炮孔直径的有限元数值模拟,获得不同孔径炮孔孔壁压力沿炮孔轴向分布结果,并将模型试验和数值模拟结果与理论分析结果进行了对比分析。研究结果表明:耦合装药孔壁压力沿炮孔轴向方向呈现不均匀分布,起爆点近区孔壁压力急剧增大,达到最大压力峰值后开始衰减,最后孔壁压力趋于平稳波动的特征；炮孔直径与孔壁压力存在正相关,最大压力峰值和平稳波动阶段孔壁压力随炮孔直径增大而增大；在d=40 mm炮孔轴向孔壁压力的理论计算值与模型试验、数值模拟结果相对误差均较小,验证了理论分析的合理性。

Abstract:

In order to analyze the characteristics of axial distribution of borehole wall pressure along the borehole in rock blasting, the axial distribution of borehole wall pressure along the borehole of coupled charges with different borehole diameters was studied by combining theoretical analysis, model testing, and finite element simulation. Firstly, based on the theory of spherical detonation wave, a model of the detonation wave propagation in the borehole was established. Based on the relationship between the incidence angle of the detonation wave and the diameter of the borehole, the theoretical calculation formula of the borehole wall pressure under different propagation stages of detonation was derived, and the change curve of the borehole wall pressure along the axial borehole wall with different borehole diameters was obtained. In order to verify the rationality of the theoretical analysis, the concrete thick wall cylinder model test was further used to monitor the pressure of the borehole wall by using a high-speed multichannel dynamic strain test system. Meanwhile, finite element numerical simulation of different borehole diameters was established to obtain the axial distribution of borehole wall pressure results of different borehole diameters. And the model test and numerical simulation results were compared with the theoretical analysis results. The results show that the coupled charge borehole wall pressure presents an uneven distribution along the axial direction of the borehole, and the borehole wall pressure near the detonation point increases sharply, begins to decrease exponentially after reaching the maximum peak pressure, and finally tends to fluctuate steadily. There is a positive correlation between the borehole wall pressure and the borehole diameter. The maximum peak pressure and the stable fluctuation stage of the borehole wall pressure increase with the borehole diameter. The relative error between the theoretical calculation value of the axial borehole wall pressure at d=40 mm and the results of the model test and numerical simulation is small, which verifies the rationality of the theoretical analysis.