二维非测速条件下声发射震源定位方法数值验证

来源期刊:中南大学学报(自然科学版)2020年第8期

论文作者:张光 吴顺川 张诗淮 郭沛 储超群

文章页码:2299 - 2312

关键词:颗粒流理论;应力波;互相关理论;二维震源定位;定位精度;场源效应

Key words:particle flow theory; stress wave; cross-correlation theory; two-dimensional source location; location accuracy; source effects

摘    要:基于离散元方法构建平板模型,研究应力波信号传播规律。在平板模型上布设震源点激发应力波作为主动震源,布设监测点记录应力波传播信息,采用3种典型监测点布设方式(等腰直角三角形、一般直角三角形和等边三角形)在非连续介质中进行二维非测速条件下定位试验研究,探讨应力波在三维FJM模型中的传播规律。研究结果表明:1) 互相关技术能够准确计算应力波信号到达相邻监测点的时延,互相关系数可用于评估应力波衰减规律;2) 数值模拟计算所得震源定位结果集中在实际震源周边,且定位误差较小;3) 采用正弦波激发方式所得3种布设方式计算震源位置较优点的比例分别为100.0%,100.0%和87.5%,采用雷克子波激发方式所得3种布设方式计算震源位置较优点的比例分别为100.0%,95.8%和95.8%;4) 在震源处施加集中力,各监测点P波位移场在施加力方向(z方向)上最大,在垂直于施加力方向(x和y方向)上无位移;平板上各监测点实际振幅与位移场远场项理论解相符。

Abstract: Based on the discrete element method, a plate model was constructed to study the propagation rule of stress wave signals. The source point was established to stimulate stress wave as the active source on the plate model, and the monitoring points were set up to record the stress wave propagation information. Three typical monitoring point layouts (isosceles right triangle, general right triangle and equilateral triangle) were adopted to carry out the source location test under the two-dimensional non-velocity measurement conditions, which was simulated in the discontinuous medium. Further, the propagation law of stress waves in the three-dimensional flat-joint model was explored. The results are as follows. 1) Time delay of the stress wave signals reaching the adjacent receivers can be obtained accurately through cross-correlation technique, and the cross-correlation coefficient analysis can be used to evaluate the attenuation law of stress wave. 2) The source locations obtained by numerical simulation are clustered around the actual sources, and the location error is small. 3) The proportions of the better source location calculated by three typical layouts which are simulated by sine wave are 100.0%, 100.0%, and 87.5% respectively, while those which are simulated by ricker wavelet are 100.0%, 95.8%, and 95.8%, respectively. 4) When a concentrated force is applied in the source, the P wave displacement field is the maximum along the axis of applied force (z direction), and there is no displacement in the direction perpendicular to the applied force(x and y direction). The actual amplitudes of receivers are well matched with the theoretical calculation results of the far-field terms.

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