Dispersion phenomena of SH-Wave caused by obstacle in soil strata

• Main Authors: Yan-June Suen, 孫延忠
• Other Authors: J. J. Charng
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/77450302200090159905

碩士 === 國立成功大學 === 土木工程學系 === 87 === Since the need for reliable and quantitative techniques for testing and evaluation of the integrity of structures or materials, interests in the area of non-destructive test (NDT) have been increased during the last three decades. By the similar technique, we can study the propagation, scatting and attenuation of elastic stress waves to determine many fundamental properties of soil strata and to detect the underground obstacles. The purpose of this research is using the numerical-simulation method to study the dispersion phenomena of SH-wave caused by obstacle, which embedded in 2-D half-space and 2-D double layers soil strata respectively. The basic idea is using boundary element method (BEM) accompany with finite element method (FEM) which makes up the so-called hybrid method to build up the numerical model to find out the frequency-domain dispersion response of SH-wave. Where FEM is using to treat the nearby area of obstacle, and BEM which simply the boundary conditions (radiation conditions) simulation and save the computation time consumed is using for the remote area. The Ricker wavelet force functions with different characteristic frequencies are adopted to simulate surface impact source. Then with the numerical model that mentioned earlier, the response spectrum could be obtained, then using both the convolution theory and Fast Fourier Transform technique, the transient response waveform can also be obtained. The major parameters that this research proposes to study are the different embedded lengths, the properties of obstacle and group effects.