利用有限元方法对Rayleigh 面波的波场特征进行数值模拟,比较不同网格长度对Rayleigh 面波频散的影响,针对20 Hz的主频震源,确定当网格划分长度为0.5 m 时可满足要求。由于Rayleigh 面波散射的时距关系为双曲线,在地面布置检波器可接收到地震信号,根据地震记录所携带的地质信息对非均匀地质体进行查找,通过数值模拟验证其有效性。以Lafayette 体育馆的空洞为例,研究表明Rayleigh 面波勘探结果与电法探测的结果吻合。通过频散数据按等效半空间法,反演得到V-H 频散曲线排列和x-H-V 速度等值线图,在勘探深度范围内,能较准确地确定地下空洞的位置。
The industry urgently needs economic exploring methods to check and find the underground cave, with physicalmechanical properties different from the around medium. One of the exploring methods is the use of the Rayleigh surface wave. The Rayleigh surface wave theory and the dispersion characteristics in transmission are discussed in this paper, and the Rayleigh surface wave field characteristics are simulated by the finite element method. Shaking with different main frequency epicenters, some models are established with dissimilar depth and size, and tallied up the results of the kinetics and the dynamics characteristics of the Rayleigh surface wave. Using the experiment result of the Rayleigh surface wave exploring methods in Lafayette University's gymnasium from southeast to northwest, for instance, this methods in checking and finding the underground cave are discussed.
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