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A Study On The Characterristics Of Geo-Technically Different Sites By Surface Wave Inversion Method
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 12th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Mar 1999, cp-202-00012
Abstract
This study aims at the characterization of two geotechnically different sites by an inversion<br>analysis of surface wave dispersion. Site #l was a construction site where loose soil layer<br>overlays weathered gneiss zone. Site #2 was reclaimed land where dredged ocean sediments<br>is underlain by original ocean sediments. The phase velocities of Rayleigh waves were<br>obtained by FFT of the Rayleigh waves of the sites. An initial velocity model was assumed<br>from the phase velocities. The final shear wave velocity profiles as well as the spatial<br>resolution of the profiles were obtained using the generalized inverse method. The shear wave<br>‘velocity of site #l increases gradually to a depth of 10 meter while that of site #2 shows a low<br>velocity zone at a depth of 1 meter. Then, it increases rapidly to a depth of 3 meter, and stays<br>almost constant up to a depth of 10 meter. The spatial resolution of the shear wave profiles is<br>better in the shallower layers. This study indicates that the inverse method of surface wave<br>dispersion can be used effectively to characterize geotechnical sites with reasonable spatial<br>resolution; lm of averaging thickness in the upper 3m, 2 m averaging thickness in 3-6 meter<br>depth, 3-4 m averaging thickness below 6 meter depth.