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当前煤巷地震槽波超前探测数值模拟主要以二维波场研究为主,难以精确模拟三维全波场特征和全空间观测方式接收的地震记录。本文应用三维弹性波动方程的交错网格有限差分算法模拟了在巷道迎头前方煤层中以纵波震源激发的三维全波场。采用取平均值的办法实现了交错网格地震波场模拟的振动速度三分量同点记录。查明了三维顶底板对称煤巷模型和非对称模型中传播的波型及其传播特征。研究发现巷道迎头前方煤层内Rayleigh型槽波能量较强,Love型槽波能量较弱,煤层内巷道迎头反射Rayleigh型槽波在煤层顶、底板中泄露能量较小,在煤层中传播距离较远;在巷道周围存在巷道面波和折射头波;在煤巷两侧煤层内接收的地震记录中Rayleigh型槽波能量较强,受头波和面波的干扰较弱,而Love型槽波能量较弱,受到相对强能量头波和面波干扰,难以识别;增加接收点在煤层中的深度可以有效降低面波对Rayleigh型槽波的干扰,但不能有效减弱面波对Love型槽波的干扰。基于以上波场认识,发现传统的采煤工作面Love型槽波构造探测方法难以适用于掘进煤巷构造超前探测,Rayleigh型槽波可以用于掘进煤巷构造超前探测。
At present, the numerical simulation of seismic detection of slot seismic waves in coal roadways is mainly based on two-dimensional wavefields. It is difficult to accurately simulate the three-dimensional full-wave field characteristics and the seismograms recorded in the full-space observation mode. In this paper, a three-dimensional full-wave field excited by a longitudinal wave source in the coal seam ahead of the roadway is simulated by the staggered-grid finite difference method using three-dimensional elastic wave equation. The method of averaging is used to realize the three-component vibration velocity simulation of staggered-grid seismic wavefield. The wave patterns and their propagating characteristics of three-dimensional symmetrical roof and floor symmetrical coal lane model and asymmetric model were found out. It is found that Rayleigh slot wave energy in front coal seam is stronger and that of Love slot wave is weaker. Rayleigh slot wave with head-on reflection Rayleigh slot wave in coal seam has smaller leakage energy and lower propagation distance in coal seam Rayleigh slot wave energy is stronger in the seismic records received in the coal seams on both sides of coal seam, and the interference of the front wave and the surface wave is weaker. The wave energy of the Love groove wave Which is weak and can not be recognized by the relatively strong energy front and surface waves. Increasing the depth of the receiving point in the coal seam can effectively reduce the interference of surface waves to the Rayleigh slot wave, but it can not effectively reduce the influence of surface waves on the Love groove wave interference. Based on the knowledge of the above wave fields, it is found that the traditional detection method of Love-type slot wave structure in coal mining face is not suitable for advanced detection of coal roadway. Rayleigh-type groove wave can be used for advanced detection of coal roadway.