周期性层状含孔隙、裂隙介质模型纵波衰减特征

地震波在含孔隙、裂隙斑块饱和介质传播过程中会诱发多个尺度孔隙流体流动而产生衰减和速度频散.在含有宏观尺度“Biot流”和介观尺度“局域流”衰减诱导机制的周期性层状孔隙介质模型基础上，引入了微观尺度硬币型和尖灭型裂隙“喷射流”的影响，构建了周期性层状含孔隙、裂隙介质模型.利用双解耦弹性波动方程的方法数值计算了该模型地震频带的纵波衰减和速度频散并与周期性层状孔隙介质模型做了对比研究.分析了该模型在不同裂隙参数（裂隙密度、裂隙纵横比）及裂隙体积含量下的纵波衰减和频散特征，裂隙密度越高对于纵波衰减和频散的影响越大，裂隙纵横比越小，由裂隙引起的纵波衰减部分向高频段移动，裂隙体积含量越少，纵波衰减先降低后小幅增加再降低，频散速度增加，并逐渐接近于周期性层状孔隙介质模型的纵波衰减和频散速度曲线.最后研究了周期性层状含孔隙、裂隙介质模型有效平面波模量的高低频极限以及流固相对位移在该模型中的分布特征.

The attenuation of P wave in a periodic layered porous media containing cracks

The attenuation and dispersion of seismic wave will occur because of the fluid flow of different scales in the porous medium when the seismic wave propagates in saturated medium. We build a periodic layered porous media containing cracks by introducing two kinds of microscopic "squirt-fluid" mechanism for the coin-shaped and pinchout-shaped cracked porous medium into the layered-White model based on the attenuation mechanisms of macroscopic "Biot" flow and mesoscopic local flow, we then solve the poroelastic equations using the Dutta's mathematic techniques which make equations uncoupled for solutions to get the attenuation and dispersion velocity of P wave of the model and compare with the results of the layered-White model. The characteristics of attenuation and dispersion of P wave for the model are analyzed with the change of the parameters of the two kinds of cracks, namely crack density and crack aspect ratio, and the content of cracks. With the increase of the crack density of the coin-shaped and pinchout-shaped cracked porous medium, the influence on the attenuation and velocity of P wave increases. When the crack aspect ratio increases, a portion of attenuation of P wave moves to the higher frequency band. When the content of the crack decreases, which means that the crack density and aspect ratio reduces, the peak of attenuation of P wave decreases firstly and then increases, finally decreases again, and the velocity of P wave increases. The results finally approach to that of the layered-White model. Finally, we study the low and high frequency limit of the model and the character of the relative displacement of the model containing coin-shaped cracks.