非饱和多孔介质中弹性波的传播特性

基于混合物理论,引入Bishop有效应力公式,建立了非饱和土中的动力控制方程.经过理论推导,给出了体波的传播速度及衰减的解析表达式.同时发现,在非饱和土中存在3种压缩波(P1、P2和P3波)和1种剪切波(S波).数值分析表明:4种体波均具有不同程度的弥散性,在一定的频率范围,波速随着频率的升高而增大,其中P2、P3波的波速受频率的影响强烈;饱和度对波的传播速度亦有显著的影响,且在不同的频率范围,其影响规律不同,在有实际工程意义的低频段,饱和度的增高将导致P1、P3波的波速增大和P2、S波的波速减小.4种体波中P2、P3波的衰减较大,且随着频率的升高衰减迅速增加,而P1、S波的衰减则很小,受频率的影响也相对较小.

Characteristics of wave propagation in partially saturated poroelastic media

Based on mixture theory, the dynamic governing equations are established for partially saturated poroelastic media by introducing Bishop's effective stress formula. The analytical expressions of wave velocity and attenuation are deduced,which demonstrates the existence of three types of compressive waves (P1,P2 and P3 wave) and a shear wave (S wave). Numerical analysis indicates that all four types of waves are dispersive. Frequency has significant effect on the velocity of P2 and P3 waves. The velocity of four waves becomes higher with the frequency increasing in a range. The influence of saturation on wave velocity is also obvious. With the degree of saturation decreasing,the velocity of P1 and P3 becomes lower and the Velocity of P2 and S becomes higher for the case of low-frequency range. Among the four types of body wave,the attenuation of P2 and P3 is much greater than that of P1 and S. With the frequency increasing,the attenuation of P2 and P3 raises rapidly.