斜面地盤が短周期微動のH/Vスペクトルと分散曲線に与える影響: 2.5次元表面波入射解析による検討

摘要

常時微動に関する研究は古くより行われており、近年では、S波速度構造が比較的簡便に求められるとして微動のアレイ観測から位相速度を推定する方法例えば1)~3）や、微動の3成分観測から得られるH/Vスペクトルを用いて逆解析を行う方法4）、またこれらの観測値を同時に逆解析することもある5）,6）。%In this paper, wave propagation in an irregular ground due to incident surface waves is formulated by combining the 2.5 dimensional thin layered element method and the 2.5 dimensional finite element method. From this study, the following conclusions are made: 1. From the analysis of (he microtremor wave field due to various incident surface (Rayleigh and Love) waves, it has pointed out that H/V spectra and dispersion curves are influenced by both body and surface waves generated from the irregularity (slope in this study) of the ground. 2. It is also confirmed that effect of interference between the incident wave and waves generated from the slope changes depending on the angle of incidence. 3. A comparison with the observation data has shown that the 2.5-D analysis can give good results when compared to the 1 -D or 2-D analysis. 4. Estimated phase velocities from observation data show a tendency of accuracy degradation in the vicinity of the H/V spectral peak.