地震槽波的数学-物理模拟初探

针对地震槽波在低速层的传播特性，开展了煤层内地震槽波勘探的数值模拟和物理模拟研究的初探工作.在数值模拟研究方面，采用交错网格有限差分法对煤层中的地震槽波进行三分量全波场模拟.基于波场快照和人工合成地震记录研究了不同模型中的波场特征和各种波型的传播规律.在物理模拟方面，通过选用不同配比的环氧树脂和硅橡胶类材料构建地震槽波物理模型，利用透射法和反射法观测系统获得了清晰的地震槽波记录以研究槽波的地震学特征.研究表明，在煤层内槽波的地震波场中，Love型槽波的能量小于Rayleigh型槽波的SV分量，大于Rayleigh型槽波的SH分量.相对于Love型槽波和Rayleigh型槽波的SH分量，Rayleigh型槽波的SV分量在围岩中的泄露能量较强.在煤层界面附近的围岩中，地震波仍以槽波形式传播，随着距离的增加能量逐渐衰减.随着煤层变薄，煤层槽波主频向高频方向移动，频散现象增强，传播速度增大.

Preliminary study on the numerical-physical simulation of seismic channel waves

In view of the propagation characteristics of seismic channel waves in the low-velocity layer, we make a preliminary study on the numerical simulation and physical simulation of these waves. In the aspect of numerical simulation, this paper adopts the staggered-grid finite difference method to conduct a 3-D seismic wavefield forward modeling of the channel waves in the coal seam. Based on the wave field snapshots and synthetic seismic records, the wave field characteristics of different models and the propagation laws of various waves are studied. In the physical simulation, this paper adopts the different proportions of the epoxy resin and the silicone rubber material to build a physical model. The clear channel waves are recorded by the transmission and reflection observation system. The results show that in the seismic wave field excited by the explosive source in the coal seam, the energy of Love channel waves are less than those of SV component of Rayleigh channel waves and greater than those of SH component of Rayleigh channel waves in the coal seam. With respect to the SH component of Rayleigh channel waves and Love channel waves, Rayleigh channel waves leakage energy in the surrounding rock is relatively strong. The seismic waves in surrounding rock near the coal seam still propagate as channel waves. With the decreasing thickness of the coal seam, the channel waves are shifting toward dominant frequency, with stronger dispersion, and larger wave speed.