基于FDTD方法研究重力作用下瑞利波传播特性

Propagation characteristics of Rayleigh wave under gravity based on FDTD method

瑞利波(R波)在地质勘探和无损检测等许多领域都得到了广泛的关注和应用,重力作用对其的影响不可避免.基于前人提出的重力作用下的R波波速函数,进一步分析了不同弹性参数下重力对于该波速的影响,给出了近似波速函数的适用范围;采用时域有限差分(FDTD)方法、交错网格离散格式及扩展边界条件,模拟了微分高斯脉冲(DGP)激励下,准半空间体各向同性线弹性介质中的波传播问题,得到了更接近理论结果的波速值,同时进一步分析了重力对时域和频域响应等方面的影响.通过分析得到,为了更为准确地预测实验结果,有必要在模拟中加入重力作用.

R wave is short for Rayleigh wave. R wave, on which the effect of gravity is generally inevitable, has received considerably extensive attention and been widely used in many fields, such as geological exploration, nondestructive test, etc. The effects of gravity on R wave velocity for elastic parameters were further analyzed based on available R wave velocity function, and the applicable range of the approximate one was given as well. Wave propagation through quasi-half-space isotropic linear elastic medium with gravity, under the excitation of differentiated Gaussian pulse （DGP） was studied by finite difference time domain （FDTD） method with staggered grid discretization, and extended boundary conditions were introduced. Velocity values obtained were closer to the theoretical ones. Meanwhile, the influence of gravity on time domain, frequency domain response was discussed. By analyzing the theoretical and numerical results, it is necessary to take the effect of gravity into account in simulation for more accurate prediction.