离散介质波场正演模拟与弱化性影响分析

从流变力学角度建立的离散介质本构关系同时考虑了介质的弹性、粘性与弱化性,与损伤力学建立的本构关系比较表明弱化因子具有损伤因子的力学意义。本文采用交错网格伪谱法正演模拟了离散介质中波的传播,并以平面波解分析了体波的频散和介质的吸收系数。高频和低频情况下波场数值模拟的结果是:饱和多孔介质中体波速度随弱化因子的增加而降低,介质吸收系数随弱化因子的增加而增加,弱化性对不同体波频散的影响程度不同。

Wave field forward modeling and theoretical analysis of weakness in discrete media

The elasticity, viscosity, and weakness properties are taken into account in the relationships derived from rheology mechanics. Comparing with the corresponding relationships derived from damage mechanics, we find the weakness factor has the same significance as the damage factor. We simulate the wave field using a staggered-grid pseudo- spectral method to show the influence of the weakness factor qualitatively. Applying the analytical solution of plane waves, we give the velocity and attenuation coefficient of three body waves, which are affected by the wave frequency and the weakness factor of saturated discrete media. Our results show that velocity decreases with increasing weakness factor, the attenuation coefficient increases with an increase in the weakness factor, and that the influence of weakness depends on the mode of the body waves.