報告書番号

383017

タイトル（和文）

軟質地盤上の大型基礎の動的挙動に関する実証研究（その２）３次元Ｆ．Ｅ．Ｍ．複素振動解析法（ＴＢ３Ｄ１）による建屋－基礎－地盤連成系の振動予測解析と基礎加振時計測の照合

タイトル（英文）

A STUDY ON THE DYNAMIC BEHAVIOR OF A LARGE-SCALE FOUNDATION ON THE SOFT GROUND (2) -PREDICTIVE ESTIMATES OF DYNAMICBEHAVIORS IN THE FOUNDATION EXCITATION AND THE COMPARISON WITH MEASURED RESULTS-

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所の軟質地盤立地における耐震安定性の究明を図ることを主たる目的の一つとして，洪積地盤上に建設された大型基礎の基礎加振時の動的挙動の予測解析を実施し，実測値と対比した。解析には当所で開発された３次元Ｆ．Ｅ．Ｍ．複素振動解析法（ＴＢ３Ｄ１）を用い，併せて他の解析手法等との比較・考察を行なって次の知見を得た。１）ＴＢ３Ｄ１による解析値は基礎でも地盤でも，振幅，位相両特性とも計測値と良好な合致が得られた。土圧分布でも概ね良好な結果を得た。２）擬似３次元ダンパー付の２次元Ｆ．Ｅ．Ｍ．解析では，基礎－地盤系の１次の共振点はほぼ正確にとらえているが，振幅は相当低めに出る結果となり，埋込みの深いケースではこの手法は減衰がききすぎる，との従来の指摘を裏付けた。３）スウェイ・ロッキング２自由度系モデルによる検討でも，地盤物性を適切に算定すれば基礎挙動の概略を推定できる結果が得られた。

概要 （英文）

A PREDICTIVE ESTIMATE OF THE DYNAMIC BEHAVIOR OF A LARGE-SCALE CONCRETE FOUNDATION ON THE SOFT GROUND IN THE FOUNDATION EXCITATION WAS CARRIED OUT. THE COMPUTER PROGRAM NAMED TB3D1 WAS USED IN THE ANALYSIS WHICH WAS DEVELOPED IN CRIEPI. TB3D1 IS THE CODE FOR SOIL-STRUCTURE INTERACTION TO SIMULATE THE HORIZONTAL EXCITATION OF BUILDINGS AND OR FOUNDATIONS. IN THE CODE TB3D1,3-D REGION WITH RECTANGULAR CO-ORDINATES IS ABLE TO BE INTRODUCED AMONG THE AXISYMMETRIC REGIONWITH CYLINDRICAL CO-ORDINATES CALLED TRANSMITTING BOUNDARY.THE CALCULATED RESULTS WERE COMPARED WITH THE OBSERVED. OTHER NUMERICAL METHODS WERE ALSO APPLIED, AND THEY WERE MUTUALLY COMPARED. AS THE RESULT, THE FOLLOWINGS WERE MADE CLEAR. (1)FROM THE POINT OF VIEW OF BOTH AMPLITUDES AND PHASE LAGS, RESONANCE CURVES OBTAINED FROM TB3D1 AGREED FAIRLY WELLWITH THOSE FROM OBSERVATION BOTH ON THE FOUNDATION AND ON&IN THE GROUND UP TO 12 HZ.AS TO THE CONTACT PRESSURE DISTRIBUTION, CALCULATED RESULTS WERE TOLERABLE. THUS, TB3D1 IS CERTIFIED TO HAVE ENOUGH EFFECTIVENESS AND USEFULNESS. (2)BY 2-D FEM ANALYSIS WITH PSEUDO 3-D DAMPERS, THE 1ST NATURAL FREGUENCY COINCIDED APPROXIMATELY WITH THE OBSERVED,BUT THE AMPLITUDE WAS FAR SMALLER THAN THE OBSERVED ONE. IT SHOWS THAT THE DAMPING FACTOR IS OFTEN OVERESTIMATED ESPECIALLY WHEN THE PESUDO 3-D METHODIS APPLIED TO THE DYNAMIC ANALYSIS OF DEEPLY EMBEDDED FOUNDATION. (3)ACCORDING TO THE SWAY-ROCKING MODEL WITH TWO DEGREES OF FREEDOM, THE DYNAMIC BEHAVIOR OF THE FOUNDATION WAS ROUGHLY SIMULATED. IN THIS CASE, APPROPRIATE ESTIMATION OF THE PHYSICAL PROPERTIES OF THE BEDDING STRUCTURE OFFERS A KEY FOR THE GOOD SIMULATION.

報告者

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