基于地脉动谱比法的场地特征参数快速测定

Micro-tremors at 37 sites were observed and measured. Correlations among the micro-tremor H/V spectra predominant frequency and site characteristic parameters including thickness of sediment, equivalent shear wave velocities in different depths, and site period were studied. Comparing these correlations and the study results of ground motion H/V spectra in different regions, the feasibility and accuracy of using the micro-tremor H/V spectra method to quickly measure site characteristic parameters were explored. Results showed that the predominant frequency of micro-tremor H/V has a strong correlation with the thickness of sediment, if using the micro-tremor H/V spectra method to measure thicknesses of sediment in different regions, their relative differences within a frequency range of 1-2 Hz are less than 15%, the relative differences increase beyond this frequency range; the predominant period of the micro-tremor H/V spectra is almost the same as the site sediment equivalent period; when the micro-tremor H/V spectra's predominant period >0.5 s, the site's equivalent shear wave velocities V_s20 and V_s30 as well as equivalent periods T_s20 and T_s30 have little changes, they have average values of 200 m/s, 250 m/s, 0.8 s and 0.6 s, respectively.