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为探讨瑞利波在复杂介质中的形成机理和传播规律,正确认识瑞利波实测结果,提高反演结果的精度,从弹性波方程出发,采用4×10阶高阶交错网格有限差分方法对弹性半空间介质进行全波场模拟。通过对均匀半空间介质、正常地层顺序地基模型和含有低速夹层地基模型的正演模拟,获得了它们各自的地震记录和瞬时快照。由模拟结果可知:以往常规的低阶有限差分方法存在严重的数值频散,不适合用来研究介质中瑞利波的频散特性;而高阶交错网格有限差分法可有效地压制模拟中的数值频散影响,其层状介质的模拟结果与以往频散方程的计算结果吻合;今后可采用此方法模拟非层状的复杂介质模型,从而进一步根据频散曲线研究复杂介质的频散规律,指导实际勘探工作。
In order to explore the formation mechanism and propagation law of Rayleigh wave in complex media, to correctly understand the measured results of Rayleigh wave and improve the accuracy of inversion results, a 4 × 10 order high-order staggered-grid finite difference method Full-wavefield simulation of elastic half-space media. Their respective seismograms and instantaneous snapshots were obtained by modeling the homogeneous half-space media, normal-sequence base models, and forward modeling with low-speed sandwich-base models. The simulation results show that the conventional low order finite difference method has serious numerical dispersion and is not suitable for the study of the dispersion characteristics of Rayleigh waves in medium. The high order staggered grid finite difference method can effectively suppress the simulation The numerical simulation of layered media agrees well with that of previous dispersion equations. In the future, this method can be used to simulate non-layered complex media models, so that the dispersion law of complex media can be further studied according to the dispersion curve , Guide the actual exploration work.