| Summary: | 碩士 === 國立聯合大學 === 土木與防災工程學系碩士班 === 97 === This study employs MASW (Multichannel Analysis of Surface Wave Method) with and without source to estimate shallow shear wave velocities which are used to predict the types of soil. Also the profile of P-wave’s velocity is inverted by the refraction seismic method. The dispersion curves, auto spectra and wave velocities of the site-earth conditions for different water content are compared between the data with and without source. We chose four different geologic experimental fields which include the backyard of the Department of Civil Engineering and the Bajia zone at the United University, and the mountain fields of Sanyi Huoyan, and the riverbeds near and below MiaoLi Hsing Dong Bridge. This study attempts to provide a set of simple effective method to extrapolate the properties of strata and may help the disaster prevention in the future.
The results show that experiments by the refraction microtremor technique are more labor-saving and more economical, and less impact for difficult terrain. Also from many experimental data we find that the sampling rate of 8ms and the record duration of 120s are the best experimental time for the refraction microtremor technique. The difference of shear wave velocity obtained from the data with and without source is within 20% in the top layer and maximum to 27% in the shallow layers. Hence, it is more convenient to measure the shear wave velocities by the method without source than the one with source. Moreover, the shear velocities obtained by the refraction microtremor technique compared with those by the borehole data are quite close, so this method has been initially proved feasible.
|
|---|
