摘要
应用Biot弹性波理论对双相介质中的瑞利波作了分析和计算,导出了复波数的频散方程和位移场失量的解析表达式.在一定介质参数范围内对频散方程进行了数值求解,得到频散曲线和衰减曲线.(1)在地震波频域内存在轻微的负频散,高频区域则有较强的正频散;(2)衰减因数随频率、孔隙度和渗透系数的增大而迅速增大;(3)对某一确定介质存在一相应的反转频率f_t,当频率小于f_t时,固相质点的偏振呈现完全相同的规律,偏振特性与频率及介质参数无关,偏振轨迹为沿波传播方向的前进型椭圆,频率大于f_t时,偏振特性与弹性半空间中的瑞利波有某些类似之处.
Rayleigh wave in two-phase medium is analysed and calculated with Biot's theory of elastic wave,The dispersion equation of complex wave number and the analytic expressions of the vector of displacement field are derived. Within a certain range of the medium parameteis, by solving the dispersion eguation with the numerical method, the dispersion curves and attenuation curves are offered.(1) There is a slight negative dispersion in frequency range of seismic wave while there exists high positive dispersion in high frequency range; (2) Attenuation constant increases rapidly with the increase of frequency, porosity and osmotic coefficient; (3) There exists a reversal frequency f, for a certain medium, when frequency is less than f_t, the polarization of material point of solid phase takes exactly on the same law. The polarization property is independent of frequency and the medium parameters.The polarization l_(QCUS) is an ellipse rolling forward along the propagation direction of the wave. While the frequency is higher than f_t, the polarizing property has some similarities with Rayleigh Wave in half space of elastic medium.
关键词
双相介质
频散方程
位移场矢量
two-phase medium
dispersion equation
vector of displacement field
attenuation factors
