介观非均匀双相介质中局域流对弹性波传播的影响

针对弹性波衰减与速度频散问题,基于Pride和Berryman的介观非均匀双重孔隙介质理论模型,推导一组用位移表示,另一组用位移及孔压表示的全新形式的耦合动力学方程组,并基于双孔介质模型,推导出弹性波的相速度与逆品质因子的解析式,重点讨论介观尺度下的局域流动对弹性波传播特性的影响.数值算例表明:快波的速度随着频率的增加而迅速增加,且介观流动损失比Biot损失至少高一个数量级;同时局域流对慢波也有着不同程度的影响.证实了局域流是波能损失和相速度频散的主要因素.

Effect of Mesoscopic Flow on Elastic Wave Propagation in Heterogeneous Double Porosity Media

Based on mesoscopic heterogeneity theory model of Pride and Berryman, coupled dynamical equations were deduced with a group of displacements, and a group with displacement and pore pressure. With double-porosity model, elastic wave expression of phase velocity and inverse quality factor are deduced. Influence of mesoscopic flow on propagation of elastic waves was discussed. Numerical examples show that velocity of fast wave increases rapidly with increase of frequency, and mesoscopic flow loss is at least higher one order of magnitude than Biot loss. Besides, mesoscopic flow has different influence on slow wave. It is proved that mesoscopic flow is the main factor of wave energy loss and velocity dispersion.