音響周波数コムによる構造物のシステム解析,2; 精密な測定データ取得法; 合理的なデータ解析法の提案

System analysis for structures by using acoustic frequency comb, 2; Accurate data measuring method; Rational data analysis method

熊澤 峰夫*; 国友 孝洋*; 西田 明美  

Kumazawa, Mineo*; Kunitomo, Takahiro*; Nishida, Akemi

アクロス(ACROSS=Accurately Controlled, Routinely Operated, Signal System)とは、精密に制御した定常的なサイン波を入力し、その応答出力の測定から、従来の方法との比較において格段に高い精度で、周波数応答(伝達関数又は周波数領域のグリーン関数)を決定する計測技術である。これは、高レベル放射性廃棄物の地層処分場や地震発生場など、地下構造の時間変動監視観測用に開発されたものである。これを人工構造物の振動特性,構造解析,監視などに適用する理論的基礎とこれに固有の課題を紹介する。また、アクロスによって得られる伝達関数データの解析手法として従来用いられてきた存否法を、3次元構造物の多数点の測定で得られる伝達関数データ群の解析用に適用した事例を示す。

ACROSS (Accurately Controlled, Routinely Operated, Signal System) is such a precise metrology of frequency response characteristics that the accurately controlled sinusoidal waves (acoustic comb) is used as an input to the linear dynamic system, and induced vibration as an output is measured by the accelerometers synchronized accurately to input. This technology has been developed to be used on a routine basis for the subsurface structural analysis and state-monitoring of the geological targets. We discuss the theoretical background and the related subjects of applying this method to the artificial structures. The transfer function data in frequency domain acquired by ACROSS is analyzed by SOMPI method, which is based essentially on AR model as a discrete equivalent of linear dynamic system. Detection of small change in the structure is demonstrated by introduction of very precise measurement by ACROSS combined with the data analysis by SOMPI method.