饱和冻土中弹性体波传播特性影响参数研究

Parametric studies of body waves propagation in saturated frozen soil

基于Leclaire对饱和双相孔隙弹性介质Biot模型的扩展,研究含有两种不同固相组分的三相多孔弹性介质中体波的传播特性。以饱和冻土为例,分析了各相体积分数、颗粒形状,接触参数等因素对波动方程中惯性参数、黏性参数、刚度参数的影响;对该三相介质模型进行了退化,分析了孔隙中只含液态水或固态冰时体波的特性;以饱和冻土为例,通过数值计算,探讨了饱和冻土中体波的相速度和衰减系数与胶结参数、接触参数、频率、饱和度、孔隙率等参数的关系。结果表明:与一般的饱和土不同,饱和冻土中存在5种体波,即3种纵波和2种横波;5种体波均具有弥散性和衰减性,且P1波、S1波弥散性和衰减性远小于P2、P3、S2波;胶结参数、饱和度、孔隙率对5种体波的传播特性影响显著,接触参数对传播特性影响较小。

Based on Leclaire’s extension of the Biot model for saturated porous elastic medium, the propagation characteristics of the body waves in a three-phase porous elastic medium with two types of solid phase components are studied. Firstly, based on the Helmholtz decomposition of the displacement vector, the characteristic equations of the body waves in saturated frozen soil are established. Then the effects of the volume fraction of each phase, the shape of the particles and the contact between the particles on the inertial parameters, viscous parameters and elastic parameters are studied. The model of saturated frozen soil is degraded. The characteristic equations and propagation characteristics of body waves are analyzed assuming only liquid water or ice in pores. Finally, a numerical calculation is carried out to explore the relationship among phase velocity, attenuation coefficient of waves and parameters of soil consolidation, saturation, porosity, particle contact, wave frequency etc. The calculation results show that, different from saturated soil, there are 5 types of body waves in saturated frozen soil, i.e. 3 compressional waves and 2 shear waves. All body waves present dispersion and attenuation. The dispersion and attenuation of P1 wave and S1 wave are much smaller than those of P2, P3 and S2 waves. Body wave propagations are significantly affected by cementation parameters, saturation and porosity, but are slightly affected by contact parameters.