摘要
针对含有软夹层介质的地质模型,研究其瑞利波合并化频散曲线随夹层厚度和埋深的变化规律,分析产生"之"字形现象的根本原因。利用传递矩阵方法计算瑞利波多模式频散曲线,以及它们在自由表面的垂直位移强度,分别按能量最大法和相对位移权值法获得合并化的频散曲线,从而获得软夹层厚度或埋深变化的合并化频散曲线。由计算结果分析可知,两种方法所获得的频散曲线的整体变化规律基本相同,"之"字形随软弱夹层厚度的增加或埋深的变浅而增多;按能量最大法合成的频散曲线,"之"字形现象的出现是由于模式之间的跳跃所引起;按位移权值法计算合成频散曲线时,产生"之"形的原因是由于从单个模式的位移占优跳至多模式的位移共同占优所致。
The authors studied variation characteristics of incorporative dispersion curves with thickness and depth of a low-velocity mid-layer,and analyzed causes of zigzag dispersion.Multi-mode dispersion curves and their ver-tical displacements at free surface of Rayleigh waves were calculated by the transfer matrix method.Then,the au-thors obtained incorporative dispersion curves by the maximal amplitude method and the weighted displacement method respectively,and knew variation characteristics of incorporative dispersion curves with thickness and depth of a low-velocity mid-layer in media.According to the modeling results,we know that the basic characteristics of incorporative dispersion curves calculated by above two methods are similar,and the number of zigzag phenomena increases with thickness and decreases with depth of the low-velocity mid-layer.A zigzag phenomenon obtained by the maximal amplitude method is due to mode jumping.However,zigzag phenomena obtained by the weighted displacement method are due to mode jumping from one mode to multi-mode.
出处
《煤田地质与勘探》
CAS
CSCD
北大核心
2011年第2期61-65,共5页
Coal Geology & Exploration
基金
教育部高等学校特色专业建设点项目(TS11027)
关键词
瑞利波
“之”字形频散
传递矩阵法
能量最大法
相对位移权值法
Rayleigh waves
zigzag dispersion
transfer matrix method
maximal amplitude method
weighted displace-ment method
