Construction of motion and deformation field in granite under tamped explosion using wave propagation coefficient
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摘要: 为利用球面波实验测得的有限个粒子速度信息来分析地下爆炸下介质的运动及变形特性,基于黏弹性球面波理论和局部黏弹性等效假设,提出了一种构建地下爆炸运动及变形场的新方法。首先,利用0.125 g TNT填实爆炸下花岗岩中相邻测点的粒子速度频谱给出相应的频谱比;其次,结合黏弹性球面波理论给出的理论频谱比求解出相邻测点之间区域内等效的球面波传播系数;再次,利用局部黏弹性等效假设给出相邻测点之间任意一点的粒子速度频谱,再通过傅里叶逆变换给出粒子速度的时域波形;最后,利用运动场和变形场的物理关系,完成整个分析区域内运动场和变形场的构建。结果表明:由相邻测点反演得到的波传播系数,可高精度地构建相应测点之间区域内介质的运动及变形场;在半径15~50 mm区域内,径向压缩应变峰值约从1.7×10−2降为2.1×10−3,切向拉伸应变峰值约从4.7×10−3降为0.4×10−3,径向压缩应变率峰值约从5.1×104 s−1降为2.5×103 s−1,切向拉伸应变率峰值约从5.0×103 s−1降为1.4×102 s−1,涵盖了高应变(率)到中低应变(率)加、卸载的全过程。Abstract: In order to use the measured particle velocities from spherical wave experiment to analyze the motion and deformation characteristics of medium under underground explosion, a new method for constructing the motion and deformation field for underground explosion was proposed based on the viscoelastic spherical wave theory and local viscoelastic equivalence hypothesis. Firstly, the velocity spectrums of the adjacent measuring points in granite were used to find out the corresponding spectrum ratio. Secondly, the equivalent spherical wave propagation coefficient in the region between adjacent measuring points was obtained by combining the theoretical spectrum ratio given by viscoelastic spherical wave theory. Thirdly, using the local viscoelastic equivalence hypothesis, the velocity spectrum of the particle at any point between adjacent measuring points was dramn out, and then the time domain waveform of the particle velocity was obtained by the inverse Fourier transform. Finally, the physical relationships between the motion field and the deformation field were used to construct the motion field and the deformation field in the whole analysis region. The results showed that the wave propagation coefficients obtained from the inversion of adjacent measuring points can construct the motion and deformation fields of the medium in the region between corresponding measuring points with high precision. Within the radius of 15-50 mm, the peak value of radial compressive strain decreased from 1.7×10−2 to 2.1×10−3, the peak value of tangential tensile strain decreased from 4.7×10−3 to 0.4×10−3, the peak value of radial compressive strain rate decreased from 5.1×104 s−1 to 2.5×103 s−1, and the peak value of tangential tensile strain rate decreases from 5.0×103 s−1 to 1.4×102 s−1, covering the whole process of loading and unloading from high strain (or strain rate) to intermediate and low strain (or strain rate).
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Key words:
- underground explosion /
- spherical wave /
- granite /
- viscoelasticity /
- particle velocity /
- wave propagation coefficient /
- strain rate
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图 1 0.125 g TNT填实爆炸下花岗岩中实测的径向粒子速度[21]
Figure 1. Measured radial particle velocities in granite under the tamped explosion of 0.125 g TNT
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