報告書番号

U95027

タイトル（和文）

地震記録に基づく地盤の非線形解析手法（ＮＡＦＳＳ）の適用性の検討－鹿島地点での地震観測とその数値シュミレーション－

タイトル（英文）

STUDY ON APPLICABILITIES OF NONLINEAR RESPONSE ANALYSIS METHOD (NAFSS) OF GROUND TO EARTHQUAKE RECORDS -EARTHQUAKE OBSERVATIONS AND ITS NUMERICAL SIMULATIONS AT KASHIMA SITE-

概要 （図表や脚注は「報告書全文」に掲載しております）

当所で開発した有効応力に基づく地盤の非線形地震応答解析手法の適用性を検討するため，詳細な地盤調査・試験に基づいた地震観測記録の数値シミュレーションを実施した。その結果，地表で１００ガル程度の中規模地震時の地盤の加速度応答や間■水圧応答を本解析法によって良好に模擬し得ることを確認した。また，強地震を対象とした数種類の模擬地震による比較解析により，地震波の速度応答スペクトルの形状は地盤のせん断応力に影響を及ぼし，長周期成分が卓越する地震ほどせん断応力が大きくなること，地震波形に含まれる繰り返し回数が間■水圧の上昇量に影響を及ぼすことを解析的に示した。

概要 （英文）

SYNOPSIS: STABILITY EVALUATION OF GROUND DURING EARTHQUAKES IS AN IMPORTANT PROBLEM FOR LARGE-SCALE STRUCTURES CONSTRUCTED ON QUATERNARY GROUND WITH A HIGH GROUND WATER LEVEL. CRIEPI HASDEVELOPED A NONLINEAR RESPONSE ANALYSIS METHOD TO PREDICT THE DEFORMATION AND EXCESS PORE WATER PRESSURE OF THE GROUND DURING EARTHQUAKES ANDHAS VERIFIED ITS APPLICABILITYS BY SIMULATING SEVERAL MODEL TESTS. THERESULTS OF THE NUMERICAL SIMULATIONS OF EARTHQUAKES OBSERVED AT THE KASHIMA SITE AND CASE STUDY ANALYSES FOR VARIOUS ARTIFICIAL LARGE INPUT MOTIONS ARE DESCRIBED IN THIS REPORT. 1.EARTHQUAKE OBSERVATIONS AND NUMERICAL SIMULATIONS 1)25 EARTHQUAKES WERE RECORDED DURING OBSERVATION PERIOD FROM 1988 TO 1991. THE MAXIMUM ACCELERATION OBSERVED AT THE GROUNNDO SURFACACE WAS 114 GAL AND MAXIMUM EXCESS PORE WATER PRESSURE RATIO WAS ABOUT 0.05. 2)ACCELERATIONS AND PORE WATER PRESSURES COMPUTED BY THE NONLINEAR ANALYSIS BASED ON THE DETAILED GROUND SURVEY AND TESTS OF UNDISTURBED SAMPLES WERE IN GOOD AGREEMENT WITH THE OBSERVED DATA. 2.CASE STUDY ANALYSES FOR LARGE ARTIFICIAL INPUT MOTIONS 1)CASE STUDY ANALYSESWERE PERFORMED FOR THE ARTIFICIAL LARGE INPUT MOTIONS WITH DIFFERENR FREQUENCY CHARACTERISTICS AND ACCELERATION LEVELS AT GL-500 M. 2)THE SHER STRESS INDUCED IN THE GROUND WAS LARGER FOR EARTHQUAKES INCLUDING LONG-PERIOD COMPONENTS. 3)EXCESS PORE WATER PRESSURE WAS LARGER EARTHQUAKES INCLUDING A LARGE CYCLIC NUMBER WITH SIMILAR SHEAR STRESS AMPLIFUDE.

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