報告書番号

380048

タイトル（和文）

くり返し荷重下での永久変形に着目した土質材料の動的強度－変形特性－くり返し荷重下における飽和砂の弾・塑性モデル－

タイトル（英文）

DYNAMIC STRENGTH AND DEFORMATION CHARACTERISTICS OF SOIL MATERIALS CONSIDERING PERMANENT DEFORMATION UNDER CYCLIC LOADING

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所の立地拡大技術の一つとして，第四紀立地が考えられるが，この場合従来の岩盤立地に比して地盤が軟質であるため，地盤の安定性評価が重要な検討項目の一つとなる。その場合，地盤の非弾性的な特質を把握し，評価手法へ反映させねばならない。本研究は，そのために必要となる非弾性モデルの提案を目的として行ったものである。対象とした材料は水で飽和した砂である。この種の地盤材料は，くり返し荷重を受けると過剰間げき水圧の発生により液状化したり，また比較的小さな荷重のもとでも残留変形を生じたりする。この様な塑性的な変形特性を振動三軸圧縮試験装置により詳細に調べるとともに，それらを表現できる物性モデルを提示した。本モデルにより，地震時における砂地盤の安定性評価，特に液状化の詳細判定や残留沈下およびすべり安定性の合理的な評価が可能となった。

概要 （英文）

THE IMPORTANT STRUCTURES REPRESENTED BY THE NUCLEAR POWER PLANTS HAVE CURRENTLY BEEN CONSTRUCTED ON OR UNDER HARD AND SOFT ROCK MASSES.HOWEVER,IT MAY BE EXPECTED,IN THE NEAR FUTURE,THAT THE SECURITY OF SITE FOR THESE STRUCTURES WILL GRADUALLY BECOME DIFFICULT BECAUSE OF THE LACK OF GOOD SITE.THEREFORE,FEASIBILITY STUDIES SHOULD BE SERIOUSLY PROMOTED FOR THE CONSTRUCTION OF THESE STRUCTURES ON THECOMPARATIVELY SOFT GROUND FORMED BY THE DILUVIAL SOILS.IN THIS CASE,ITIS ONE OF THE VERY IMPORTANT SUBJECTS THAT ESTABLISH THE INVESTIGATIONMETHOD FOR THE STABILITY OF THE FOUNDATION GROUND AT STRONG EARTHQUAKE.THEN,IT IS NECESSARY TO COMPREHEND THE MECHANICAL PROPERTIES OF SOILS.BUT THERE ARE MANY UNKNOWN FACTORS ABOUT THE MATERIAL PROPERTIES AT THEVICINITY OF FAILURE UNDER CYCLIC LOADING,IN PARTICULAR,FOR THE DILUVIAL SOILS SHOWING THE COMPLICATED STRENGTH-DEFORMATION CHARACTERISTICS BECAUSE OF THE CEMENTATION AMONG THE PARTICLES,STRESS HESTORY ACCEPTED INTHE PAST,AND SO ON. THIS REPORT DESCRIBES ON THE RESULTS ON THE EXPERIMENTAL AND THEORETICAL STUDIES ON THE SATURATED SAND HAVING A VARIETY OF CONSOLIDATION HISTORY.THE RESEARCH ON THE DYNAMIC DEFORMATION BEHAVIOUR HAS BEEN CONDUCTED USING THE CYCLIC TRIAXIAL APPARATUS AND WE HAVE DISCUSSED ON THE CUMULATIVE PHENOMENAN OF EXCESS PORE WATER PRESSURE ANDSTRAIN UNDER UNDRAINED CYCLIC LOADING.OBTAINED SOME CONCLUSIONS ARE ASFOLLOWS. (1) WE HAVE CLARIFIED THE YIELDING PROPERTIES OF THE SATURATED SAND UNDER NORMALLY AND OVER-CONSOLIDATED STATES FROM THE RESULTS OF THE CYCLIC TRIAXIL TESTS. (2) WE HAVE PROPOSED THE NEW ELASTO-PLASTICITY MODEL UNDER UNDRAINED CYCLIC LOADING,WHICH HAS BASED ON THE SOME EXPERIMENTAL FACTS ON THE YIELDING CHARACTERISTICS. (3) IT HAS BEEN SHOWN THAT THE PROPOSED MODEL CAN SUFFICIENTLY ESTIMATE THE UNDRAINED DEFORMATION BEHAVIOUR OF THE SATURATED SAND HAVING ANY STRESS HISTORY.

報告者

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