報告書番号

U20

タイトル（和文）

原子力発電所の第四紀地盤立地に関する研究（その２）埋設建屋・地盤の地震応答評価法

タイトル（英文）

STUDY ON SITING TECHNOLOGY FOR NUCLEAR PLANTS ON QUATERNARY GROUND (NO.2)DEVELOPMENT AND VERIFICATION OF SEISMIC RESPONSE ANALYSES FOR EMBEDDED STRUCTURES ON QUATERNARY GROUND

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所の第四紀地盤，特に砂礫地盤に建設する技術を確立するため，実規模相当の半地下式建屋の地震観測，起振実験および砂礫地盤モデルによる振動台実験を実施し，これらの実験データ等により埋設建屋が埋設効果を有していることおよび，埋設効果の要因として，基礎底面への入力地震動の低減効果によるものが最も大きいことを確認した。また，埋設建屋の応答特性，埋設効果などの検討に必要バネ定数の算定法や３次元ＦＥＭ解析手法（ＲＥＳＰ）を開発し，地震観測実験の数値シミュレーション等によりその妥当性を実証した。さらに，大地震に対して，密な砂礫地盤は第四紀地盤として十分な支持力を有していること，また，地盤の安定性は実務的には等価線形法で評価できることを確認した。

概要 （英文）

TO VALIDATE THE SITING TECHNOLOGY FOR NUCLEAR POWER PLANTS ON QUATERNARY GROUND,ESPECIALLY GRAVELLY GROUND,WE OBSERVED VARIOUS EARTHQUAKES AND CARRIED OUT FORCED-VIBRATION TESTS ON ACTUAL EMBEDDED BUILDINGS,AND LARGE-SCALE SHAKING-TABLE TESTS ON MODEL GRAVELLY GROUND. FROM THESE TEST DATA,THE SEISMIC RESPONSE OF ACTUAL EMBEDDED BUILDINGS IS MUCH SMALLER THAN THE NEAR-FIELD MOTION. SUCH A SEISMIC-RESPONSE ADVANTAGE CAN BE INTERPRETED AS AN EMBEDDED EFFECT. THE MAJOR CAUSE OF THE EMBEDDED EFFECT IS DEGRADATION OF THE EARTHQUAKE MOTION PROPAGATING VERTICALLY UNDERNEATH THE BUILDING IN COMPARISON TO THE MOTION AT THE GROUND SURFACE. AN ANALYTICAL BASIS FOR THE EMBEDDED EFFECT WAS ESTABLISHED USING A PRACTICAL LUMPED-MASS ANALYSIS(SR MODEL),AND A MORE RIGOROUS THREE-DIMENSIONAL FINITE ELEMENT ANALYSIS (RESP) WAS DEVELOPED. MOREOVER,THE CURRENT PROCEDURE FOR DETERMINING SOIL-STRUCTURE INTERACTION IMPEDANCE IN TERMS OF SOIL SPRINGS USED IN THE SR MODEL WAS IMPROVED. THE GAVELLY GROUND WAS CONFIRMED AS HAVING SUFFICIENT BEARING CAPACITY DURING STRONG EARTHQUAKE MOTION(S2)FROM THE SEIMIC RESPONSE OF THE IDEALIZED SOIL-STRUCTURE INTERACTION SYSTEM IN THE MODEL GRAVELLY GROUND EXCITED ARTIFICIALLY BY A SHAKING TABLE. IN ADDITON,LOCAL UNBONDING ALONG THE EMBEDDED INTERFACE DOES NOT HAVE SIGNIFICANT EFFECT ON THE SEISMIC RESPONSE. THESE OBSERVATIONS MUST BE EVALUATED NUMERICALLY BY TRACING THE NON-LINEAR SOIL STRESS-STRAIN RELATIONSHIP BUT A NUMBER OF ANALYTICAL CORRELATIONS SHOW THAT AN EQUIVALENT LINEAR ANALYSIS COULD BEAVAILABLE FOR PROSPECTIVE STRAIN LEVELS.

報告者

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