| 講演要旨(和文) | | Cho et al.2006, Tada et al.2007 のCCAは半径数m以下の極小Arrayで探査可能いう利点を持ち,住宅敷地毎の地盤特性評価に有効と期待できる。本研究では,微動Simulation記録(N101:Cornou et al.2006)を使い,半径6mの6成分Array CCAと最大半径約100mで15成分SPACの分散曲線を比較した。両者は非常に良く一致したが、共に基本と1次モードの中間的な値となった。開発途上国では3成分Digital Recorder1台を保有すれば僥倖である。これへの適応性を調べる為,120度毎3成分2Setを選び,各SetのGzozoの和のGz1z1の和に対する比をCCA係数とした分散曲線は、限界周波数は6成分の場合の約1.4倍程度となり,より高周波数側で6成分CCA法及びSPAC法の結果と非常に良く一致した。 |
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| | 講演要旨(英文) | | CCA method proposed by Cho et al.2006 and Tada et al.2007 has shown a big advantage for the estimation of velocity to the depth related with seismic risk of structures by using a very small array. The performance of CCA was checked using 6 components array of 6m radius in comparison with 15 components SPAC using maximum radius about 100m, the simulated microtremor records N101 of Cornou et al.2006. CCA dispersion curve showed a good coincidence with that of SPAC. Both have phase velocity between the fundamental and the 1st higher mode. Considering on the poor condition in the developing countries where only one digital recorder of three components is available by luck, the applicability of CCA to this difficulty was checked. 2 sets of 3 components records selected at every 120 degrees showed the lower limit frequency about 1.4 times higher than that of 6 components CCA and a systematic lags at higher frequencies but opposite sense for different sets. To combine them, the ratio of the sum of Gz0z0 to that of Gz1z1 is used as CCA coefficient. The dispersion curve showed a good coincidence with 6 components CCA and SPAC but the limit frequency is remained un-improved. |
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