報告書番号

U86002

タイトル（和文）

地震時における基礎地盤の安定性評価（その１）動的解析に基づく砂・砂礫地盤の安定性評価手法の開発

タイトル（英文）

EVALUATION OF STABILITY OF FOUNDATION GROUNDDURING EARTHQUAKE (PART 1)DEVELOPMENT OF ESTIMATION METHOD OF STABILITY OF SNADY･QRAVELY GROUND BASED ON DYNAMIC ANALYSIS

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所新立地技術の一つとして第四紀地盤立地に関する研究を進めている。この場合，特に地震時の変形に関する検討が重要であるが，ここではこのことを目的とした過剰間隙水圧の発生（液状化）とその消散に伴って発生する地震時沈下量を予測するための解析手法について述べている。まず，数多くの繰返しせん断試験結果に基づき，ゆるい砂・砂礫から良く締まった密な砂・砂礫に至る幅広い地盤で適用可能な地震時における過剰間隙水圧予測手法を提案した。この方法と応答解析結果とから，地震時液状化および地盤沈下量を推定する計算手法を開発し，振動台実験との比較を通じてその妥当性を検証した。提案した予測法は，従来検討の困難であった過剰間隙水圧と地盤変形の推定を可能としたもので，第四紀地盤立地技術の確立はもとより，一般電力施設の地震時安定性評価の高度化と合理的設計に寄与するものと考える。

概要 （英文）

CRIEPI PROCEEDS PROGRESSIVELY THE RESEARCHESOF THE SITING TO THE QUATERNARY GROUND AS ONE OF THE NEW SITING TECHNOLOGY OF NUCLEAR POWER PLANTS. IN THIS CASE,IT IS IMPORTANT TO INVESTIGATE THE DEFORMATION OF FOUNDATION GROUND DURING EARTHQUAKE. HERE,WE DESCRIBE THE NUMERICAL ANALYTICAL TECHNIQUE TO PREDICT THE GENERATION OF EXCESS PORE WATER PRESSURE (LIQUEFACTION) AND EARTHQUAKE INDUCED SETTLEMENT,WHICH MAINLY RESULTS FROM THE DISSIPATION OF EXCESS PORE WATER PRESSURE. IN THE FIRST PLACE,PREDICTION METHOD ON VOLUMETRIC STRAIN DUE TO DILATANCY AND EXCESS PORE WATER PRESSURE BROUGHT ABOUT BY CYCLIC LOADINGWAS PROPOSED BASED ON THE RESULTS OF CYCLIC TRIAXIAL AND TORSIONAL SHEAR TESTS. IT IS POSSIBLE TO BRIEFLY PREDICT BY PROPOSED METHOD THE DEFORMATION BEHAVIOR OF SAND AND GRAVEL WITH WIDE RANGE OF DENSITY UNDER STRESS CONDITION THAT SHEAR STRESS IS CYCLICALLY EXECUTED. COMPUTATIONAL METHOD WAS PROPOSED TO PREDICT THE SEFTLEMENT AND THE EXTENT OF LIQUEFACTION DEVELOPET IN GROUND DURING EARTHQUAKE IN TERMS OF THE COMPUTAIONAL RESULTS ON EXCESS PORE WATER PRESSURE CALCULATED FROM TIME VARIATION OF SHEAR STRESS IN GROUND DURING EARTHQUAKE MOTION WHICH IS GIVEN BY FREQUENTLY USED AND AUTHORIZED RESPONSE ANALYTICAL TECHNIQUE AND VOLUMETRIC STRAIN PREDICTED BY THE ABOVE METHOD. THIS METHOD IS ADOPTED TO NOT ONLY ONE DIMENSIONAL PROBLEMS,BUT TWO DIMENSIONAL PROBLEMS SUCH AS SOIL-STRUCTURE SYSTEM. ADAPTABILITY OF PROPOSED PREDICTION METHOD WAS INVESTIGATED BY NUMERICAL SIMULATION FOR MODEL TESTS USING SHAKING TABLE. ASA RESULT,IT IS CONFIRMED THAT ADAPTABILITY OF PROPOSED METHOD FOR STABILITY PROBLEM OF SANDY-GRAVE GROUND UNDER EATRHQUAKE IS HIGH.

報告者

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