中文摘要：

对于存在低速层的层状介质,其对应的Rayleigh波频散曲线形状会比较特殊,频散曲线会发生＂交叉＂现象。很多人在研究中发现此现象,并且对＂交叉＂点附近的一些性质进行了研究,但是对这一现象的认识仍然不充分。例如,还没有人研究对于频散曲线＂交叉＂点位置与层状介质参数有着怎样的关系。针对此问题,主要以含低速层的三层介质为基础,推导了Rayleigh波频散曲线＂交叉＂点频率的近似计算公式,并由此分析了＂交叉＂点频率与介质参数之间的关系,该公式也适用于部分更多层的模型。

英文摘要：

Sometimes,there will be some dispersion curves that are cross for multi-layered medium that exist low velocity layer. Although some researchers have found this,and did some researches on it,the study is still not sufficient till now. For example,the relationship between the position of the cross points and the parameter of multilayered medium is still unknown. In this paper,based on three-layered medium with low velocity layer,the approximate form of the frequency formula of cross points are deduced,and the relationship between the position of the cross points and the parameter of multi-layered medium is studied based on the formula. The formula can also used for some of media that contains more than three layers.