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将多根连接钻杆近似为无约束的一维杆状体,阐述了轴向激发的弹性波在钻杆中一维纵波的传播规律:弹性波传播到钻杆顶端将产生能量较强的反射波;钻杆中弹性波各振型频率的差为一定值,且随着杆长的增加而减小.通过在钻杆底端激发、接收弹性波,利用钻杆顶端的反射波的到时和弹性波各震相的频差,根据已标定的弹性波在钻杆中的传播速度分别从时间域和频率域计算钻杆的长度,从而确定钻孔的深度.对煤矿瓦斯抽采孔进行快速抽查,取得了很好的效果.
The multi-connected drill pipe is approximated as an unidirectional one-dimensional rod-shaped body, and the propagation law of one-dimensional longitudinal wave propagating axially in the drill pipe is described. The propagation of the elastic wave to the top of the drill pipe will produce a strong reflection The difference between the frequencies of the elastic waves in the drill pipe is constant and decreases with the increase of the rod length.The elastic wave is received at the bottom of the drill pipe and the arrival of the reflected wave at the top of the drill pipe And the elastic wave phase of the phase difference, according to the calibration of the elastic wave propagation speed in the drill pipe, respectively, from the time domain and frequency domain calculation of the length of the drill pipe, so as to determine the depth of the drilling hole for coal mine gas extraction Quick spot checks, and achieved good results.