報告書番号

383050

タイトル（和文）

振動載荷時における軟岩の動的強度一変形特性

タイトル（英文）

DYNAMIC STRENGTH-DEFORMATION PROPERTIES OF SOFT ROCKS DURING CYCLIC LOADING

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所が軟岩地盤に立地される時，地震入力の大きさから，地震時における地盤の安定性評価が重要な検討課題の一つとなる。この場合，軟岩の動的強度一変形特性の把握が必要とされるが，くり返し荷重下での力学的特性に関する研究は極めて少く，未解明な点が少くない。ここでは，これらの点に着目し，多数の軟岩を対象として室内での振動三軸圧縮試験を行い，軟岩の動力学的特性について考察を行った。その結果，軟岩の動的強度は静的強度で代用できること，地震時における非線形挙動は，一般に想定されるひずみレベルでは考慮する必要はないこと，軟岩の動的変形特性は室内試験から充分な精度で推定できること，したがって軟岩地盤の動力学特性は大規模な試験法によらずとも簡便な方法で推定が可能なことが示された。これらの結果は，地震時における地盤の安定性に関する合理的評価に資することができる。

概要 （英文）

FOR THE SITING OF NUCLEAR POWER PLANTS ON THE SOFT ROCK GROUND, THE EVALUATION OF ASEISMIC STABILITY OF FOUNDATION GROUND DURING EARTHQUAKE FROM THE AMOUNT OF INPUT MOTION POINT OF VIEW COMES INTO ONE OF THE IMPORTANT SUBJECTS. GENERALLY, THE STABILITY OF ROCK MASS DURING EARTHQUAKE IS STRONGLY AFFECTED BY JOINT, BEDDING AND FAULT WHICH EXIST IN ROCK MASS. ON THE OTHER HAND, IN THE CASE OF HOMOGENEOUS ROCK MASS CONSTITUTED BY SO CALLED SOFT ROCKS, TO CLARIFY THE DYNAMIC STRENGTH-DEFORMATION CHARACTERISTICS OF ROCK ITSELF IS IMPORTANT, BECAUSE OF THE STRONG CORRELATION OF MECHANICAL PROPERTIES BETWEEN ROCKMASS AND ROCK SPECIMEM. SO FAR, THE STUDIES OF DYNAMIC STRENGTH OF SOFT ROCKS, IN PARTICULAR THE STRENGTH DURING CYCLIC LOADING, WERE VERY FEW EXCEPT THE STUDIES ON STRAIN RATE EFFECT. ALSO, THERE ARE NOT FEW THERESEARCHES OF NON-LINEAR CHARACTERISTICS ON DYNAMIC DEFORMATION PROPERTIES OF SOFT ROCKS. SO, THIS PAPER DESCRIBES THE DYNAMIC MECHANICAL PROPERTIES OF SOFT ROCKS UNDER COMPARATIVELY LARGE STRAIN LEVEL DURING CYCLIC LOADING. MAIN CONCLUSIONS OBTAINED THROUGH THIS STUDY ARE AS FOLLOWS. (1) STATIC STRENGTH MAY BE USED AS STRENGTH MOBILIZED DURING EARTHQUAKE, (2) IT IS NOT NECCESSARY TO CONSIDER THE NON-LINEAR MECHANICAL PROPERTIES FOR SHEAR STRAIN LEVEL CAUSING IN GROUND DURING EARTHQUAKE, WHICH IS COMPUTED BY EQUIVALENT LINEAR RESPONSE ANALYSIS TECHNIQUE, (3) ITIS POSSIBLE TO ESTIMATE WITH SUFFICIENTLY ACCURACY DYNAMIC DEFORMATIONPROPERTIES OF SOFT ROCKS BY LABORATORY TESTS. THESE RESULTS CONTRIBUTETO THE RATIONAL EVALUATION ON THE ASEISMIC STABILITY OF GROUND.

報告者

キーワード