多层层状介质的瑞利面波频散特性  

DISPERSION CHARACTERISTICS OF RAYLEIGH WAVES IN MULTILAYERED MEDIA

作　　者：杨天春[1] 肖巧玲[2] 

机构地区：[1]湖南科技大学土木工程学院,湖南湘潭411201 [2]湖南科技大学机电工程学院,湖南长沙410082

出　　处：《物探与化探》2009年第3期299-303,共5页Geophysical and Geochemical Exploration

基　　金：湖南省教育厅资助科研项目(06B030)

摘　　要：采用传递矩阵法对多层各向同性的层状弹性固体介质瑞利波相速度频散特性及自由表面的垂直位移强度特征进行研究,便于今后对实测频散曲线有更清楚的认识和更合理的反演解释。设计多组含4层或5层介质的层状介质模型,利用传递矩阵法计算它们的相速度频散曲线、各阶模式的地表垂直位移曲线和其合并化的频散曲线,从而了解含有绝对或相对软弱夹层的地基模型、正常地层顺序地基模型的频散特性。根据模拟计算结果可知,当地层中存在绝对软弱夹层或相对软弱夹层时,其合并化频散曲线一般会出现"之"字形现象,但二者位移曲线的特征是不同的;含绝对软弱夹层时,位移曲线是各模式分段占优,而含相对软弱夹层时,位移主要还是以基阶模式为主;对于多层介质的正常地基模型而言,其位移曲线也主要是以基阶模式为主,但其合并化频散曲线有时也会出现"之"字形现象,这主要与各介质层的层速度等参数有关。In this paper, the authors carried out forward modeling on dispersion curves and vertical displacements of Rayleigh waves by means of the transfer matrix method in muhilayered media, Their dispersion characteristics were thus detected and could be used in fu- ture practice. First, some groups of the four-layered or five-layered media were defined, and then their dispersion curves, their vertical displacements at free surface and the incorporative dispersion curve were calculated. In the end, the dispersion characteristics of differ- ent models, i.e. , the models that contain an absolute/relative low-velocity layer and the normal models, could be detected. According to the analytical results, the incorporative dispersion curve usually has the zigzag phenomenon for models that contain an absolute or relative low-velocity layer. Nevertheless, their displacement characteristics are different. When a model contains an absolute low-velocity layer, its maximal displacement curve consists of different modes. However, the maximal displacement curve of a model containing a relative low-velocity layer is composed mainly of the first mode. For the normal model, its maximal displacement curve resembles the relative low-velocity model, but its incorporative dispersion curve sometimes has the zigzag phenomenon, which is related to the parameters of models.

关 键 词：瑞利波 “之”字形频散 层状介质 传递矩阵法 

分 类 号：P631.4[天文地球—地质矿产勘探]