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研究了双层非饱和地基中Rayleigh波(以下简称R波)的传播特性问题。首先将迂曲度引入孔隙流体的渗流连续性方程,对三相孔隙介质波动方程进行修正,接着采用体波的势函数之和构建各相介质的势函数,并借助Helmholtz分解,以及考虑土层边界条件和层间连续性条件,建立了R波的弥散特征方程,分析了饱和度、迂曲度和上覆土层厚度等参数与波速和衰减性的关系。结果表明,R波波速随饱和度的增加而线性减小;在渗透系数中间区段,则随着固有渗透系数k的增大而增大;水力迂曲度τ_f对波速的影响主要体现在高频区段,而空气迂曲度τ_a的影响则非常有限;对于上软下硬地层,覆盖层厚度的增加将引起波速的减小,并逐渐趋于上覆土层本身的R波波速;且频率越高或表面层刚度越低,趋近速度越快。
The propagation characteristics of Rayleigh waves in double-layered unsaturated soils (hereinafter referred to as R-waves) are studied. Firstly, the tortuosity is introduced into the seepage continuity equation of pore fluid to correct the wave equation of three-phase porous media. Then the potential function of each phase is constructed by the sum of the potential functions of body waves. Helmholtz decomposition and soil boundary Conditions and interlayer continuity conditions, the dispersion characteristic equation of R wave is established, and the relationship between the parameters such as saturation, tortuosity and overburden thickness and wave velocity and decay is analyzed. The results show that the velocity of R wave decreases linearly with the increase of saturation, and increases with the increase of inherent permeability coefficient k in the middle section of permeability coefficient. The influence of hydraulic tortuosity τ_f on velocity is mainly reflected in high frequency The influence of tortuosity τ_a is very limited. For the upper and lower soft strata, the increase of cover thickness will lead to the decrease of wave velocity and gradually to the R wave velocity of overlying soil itself; and the higher the frequency is Or the lower the surface layer stiffness, the faster the approach speed.