報告書番号

N12016

タイトル（和文）

東北地方太平洋沖地震における変電設備の被害要因と入力地震動レベルの関係

タイトル（英文）

Relationship between the cause of substation equipment damage and the input level of earthquake ground motion during the 2011 off the Pacific coast of Tohoku Earthquake

概要 （図表や脚注は「報告書全文」に掲載しております）

東北地方太平洋沖地震では、変電設備の設計基準(300gal)を上回る最大加速度の地震動が多く観測されたものの、被害率は低く、耐震性が概ね確保されていることが確認された。将来の巨大地震に対する減災への備えとして、今回の地震で運転継続不可となった割合が高い設備の被害要因の解明し、今後の耐震裕度評価に反映していくことが重要である。本研究では、仙台変電所での275kV変圧器のブッシング被害の要因分析を、入力地震動の推定および変圧器の応答解析に基づき行った。その結果，破損したブッシングでは、推定入力地震動による発生応力が許容値を超過することを明らかにした。また、今回の地震では、全国的な強震観測網の約10％，8県において設計基準を超える記録を観測したが，設計基準の応答加速度値では，300gal超記録の約半分は設計基準のレベルを超過せず、設計基準の２倍であれば90％をカバーできることを示した。

概要 （英文）

During the 2011 off the pacific coast of Tohoku earthquake, earthquake ground motions with the peak horizontal acceleration exceeded 300 gal were observed at many stations. The number of stations that observed the peak horizontal acceleration exceeded 300 gal was significantly greater than previous damaging earthquakes. The peak acceleration value of 300 gal is the input ground motion level of the guideline about substation equipment named JEAG5003. However, the damage rates of substation equipments were not so higher than the ones by previous damaging earthquakes. Therefore it was recognized that earthquake-resistant performances of substation equipment were confirmed .In order to reduce risk from future great earthquakes, it is important to clarify the cause of high rate of equipment damage with operational failure, and to reflect the derived knowledge. In this study, the cause analysis of 275 kV transformer damage in the Sendai substation was conducted based on an estimation of input ground motion and seismic response analysis by using estimated input motion. As a result, it was revealed that the stress over allowable level occurred in the broken bushing. Moreover, it was shown that about half of the observed records with the peak acceleration exceeded300 gal did not exceed the acceleration response value by the design level of JEAG5003, and that the twice of the design level was needed to cover about ninety percent of the observed records with the peak acceleration exceeded 300 gal.

報告者

キーワード