Leaky modes and their contributions to the compressional head wave in a borehole excited by a dipole source |
| |
Authors: | XiuMei Zhang HaiLan Zhang XiuMing Wang |
| |
Affiliation: | (1) State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing, 100190, China |
| |
Abstract: | A method of studying the contributions of leaky modes to the wave field is presented based on the analysis of the Riemann surface structure of the characteristic function, and the sensitivities of contributions to various factors of interest are examimed. Numerical results show that their contributions to the compressional head wave are related to the distributions of complex poles on (−1, −1) and (0, −1) Riemann sheets on the frequency-wavenumber (ω-k) plane. For fast formations, their contributions are small, while for slow formations with large Poisson’s ratio, their contributions are large because of those complex poles with small imaginary parts near the compressional vertical branch cut. The decaying factor of the contributions of leaky modes is approximately proportional to 1/distance2. Supported by the National Natural Science Foundation of China (Grant No. 10534040) |
| |
Keywords: | dipole source Riemann surface leaky modes compressional head wave |
本文献已被 CNKI SpringerLink 等数据库收录! |
|