气饱和土中弹性波的传播特性

为分析气体对干土中弹性波传播特性的影响,基于Biot理论推导了两相介质平面波动解,以及孔隙流体自由流动和孔隙无渗流两种极限情况下的波速公式.通过数值算例,分析了气饱和土中弹性波速度与衰减特性,并与水饱和土中的计算结果进行了比较.结果表明,低频下气体对干土中波传播的影响不大,但由于气体的高动粘滞性,高频时气体的作用不可忽略;气-固耦合作用比水-固耦合作用要弱得多,气饱和土体中P1波速度比在水饱和土中显著降低,P2波速度则有所提高,而衰减则刚好相反.

Propagation Characteristics of Elastic Plane Waves in Air-Saturated Soils

To analyze the effect of air on the propagation characteristics of elastic wave in dry soil,based on Biot's theory,the plane wave solutions in porous two-phase medium were derived and the velocity formulations for free fluid and no fluid situations were obtained.The velocity and attenuation of elastic waves in air-saturated soil were given and compared with the solutions in water-saturated soil by using numerical methods.The results show that the air has a slightly influence on the propagation characteristics of elastic waves in dry soils at low frequency,but the air can not be neglected at high frequency due to the high dynamic viscosity.The air-solid interaction is much lower than the water-solid interaction.The P_1 wave velocity decreases considerably in air-saturated soils,but P_2 wave velocity in air-saturated soil is higher than that in water-saturated soil,and the attenuation rule is contrary.