報告書番号

N09030

タイトル（和文）

地震時のすべり安全率と斜面の滑落の関係に着目した岩盤斜面の耐震安定性評価フローの提案

タイトル（英文）

A development of an evaluation flow chart for seismic stability of rock slopes based on relations between safety factor and sliding failure

概要 （図表や脚注は「報告書全文」に掲載しております）

原子力発電所耐震設計技術指針においては，主に岩盤の強度に基づく抵抗力を地震力および自重による作用力で除したすべり安全率によって原子炉建屋周辺斜面の耐震安定性評価を行う．しかしながら，安全余裕に対する評価などにおいて設計用地震動を大きく超える地震動に対して安定性を検討する場合，そのようなすべり安全率評価では，検討ケースによっては，地震力の影響で，滑落しそうにない水平に近いすべり面の安全率が安定性評価基準値を下回ることもある．そのため，著者らは地震時のすべり安全率と斜面の滑落の関係に着目した岩盤斜面の耐震安定性評価フローを提案した．さらに，遠心力模型実験の結果を対象に，従来のすべり安全率と新たに提案する滑落すべり安全率を計算し，それらのすべり安全率と実験において滑落を生じた部分の関係を考察し，提案フローの妥当性を検証した．

概要 （英文）

Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake- induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is needed to evaluate the seismic stability of surrounding slopes against extremely strong ground motions.
In order to evaluate the seismic stability of surrounding slopes, the most conventional method is to compare safety factors on an expected sliding surface, which is calculated from the stability analysis based on the limit equilibrium concept, to a critical value which judges stability or instability. The method is very effective to examine whether or not the sliding surface is safe. However, it does not mean that the sliding surface falls whenever the safety factor becomes smaller than the critical value during an earthquake. Therefore the authors develop a new evaluation flow chart for the seismic stability of rock slopes based on relations between safety factor and sliding failure. Furthermore, the developed flow chart was validated by comparing two kinds of safety factors calculated from a centrifuge test result concerned with a rock slope.

報告者

キーワード