報告書番号

381009

タイトル（和文）

破砕帯を有する岩盤斜面掘削時の挙動解析と挙動観測に関する検討

タイトル（英文）

SOME CONSIDERATIONS ON THE MECHANICAL BEHAVIOUR OF ANISOTROPIC ROCK MASSES DURING THE EXCAVATION OF SLOPE

概要 （図表や脚注は「報告書全文」に掲載しております）

破砕帯および卓越した節理岩盤からなる大規模な岩盤斜面の安定性を検討するために掘削時の挙動予測と動態観測を実施した。斜面掘削時の挙動予測は原位置および室内で実施した物理・力学試験結果をもとに，岩盤の異方的な特性を考慮した非線形数値解析法により行った。その結果，（１）施工管理上実施した斜面掘削時の動態観測の結果と解析結果との比較から，両者は定量的に全て一致しないが，定性的には異方性解析手法の妥当性が確認されたこと，（２）数値解析上，斜面のすべり安全率は大きく，かつ実測結果は弾性域内にあることから，現状では十分安定な状態にあること，などがわかった。今後は異方性岩盤の実験データを蓄積することにより，本手法を用いて岩盤斜面の設計・評価をより精度よく行えるものと考える。

概要 （英文）

RECENTLY, WITH THE CONSTRUCTION OF NUCLEAR OR WATER POWER PLANTS, THE CUTTING OF SLOPE IN A LARGE SCALE IS OFTEN ACCOMPANIED. HOWEVER, SEDIMENTARY OR REGIONALLY METAMORPHIC ROCK MASSES WHICH HAVE THE DISCONTINUOUS WEAK PLANES OR THE WEAK-LOOKING LAYERS SUCHAS BEDDING, SCHISTOSITY, JOINTS OR FRACTURE ZONE, SHOW PREDOMINANT ANISOTROPIC PROPERTIES IN THEIR STRENGTHS AND DEFORMABILITIES. THEREFORE, IN THE CASE OF INVESTIGATION ON THE STABILITY OF SLOPES, IT IS NECESSARY TO TAKE ON ANISOTROPIC MECHANICAL PROPERTY INTO CONSIDERATION. IN THIS PAPER, THE METHOD FOR THE ANALYTICAL EVALUTION OF THE BEHAVIOUR DURING THE TIME OF EXCAVATION OF ROCK MASSES SLOPE IS BRIEFLY PRESENTED, IN WHICH TAKE ACCOUNT OF ANISOTROPIC DEFORMABILITY, ANISOTROPIC SHEARING STRENGTH AND THE NON-LINEAR RELATION BETWEEN STRESS AND STRAIN OF ROCK MASSES. AS THE OBJECT OF ACTUAL SLOPE OF ROCK MASSES COMPOSED ZONE AND THE REMARKED JOINTS, THE FORECAST TO BEHAVIOUR DURING EXCAVATION IS CARRIED OUT BY THE NUMERICAL CALCULATIONS OF ANISOTROPIC AND ISOTROPIC ANALYSIS AND THE COMPARISON BETWEEN BOTH RESULTS OBTAINED ARE PRESENTED HERE. MOREOVER, COMPARISON BETWEEN THE FIELD MEASUREMENT CARRIED OUT FROM THE VIEWPOINT OF SAFETY EXECUTION AND THE FORECAST OBTAINED BY THE NUMERICAL CALCULATIONS ARE PRESENTED. FROM THESE RESULTS, THE APPROPRIATENESS OF THE METHOD OF NUMERICAL ANALYSIS WAS VERIFIED TO SOME DEGREE AND ALSO THE STABILITY OF ACTUAL SLOPE WAS CONFIRMED.

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