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Title :残留係数を導入した三次元安定解析手法に関する研究
Title alternative :Studies on Three-Dimensional Stability Analysis Procedure in which the Residual Factor is Incorporated
Authors :宜保, 清一
中村, 真也
Authors alternative :Gibo, Seiichi
Nakamura, Shinya
Issue Date :May-2003
Abstract :平成13年度~平成14年度科学研究費補助金(基盤研究(C)(2))研究成果報告書
研究概要:本研究では,まず,安定解析に必要な強度定数c,φを得るために物理的・鉱物学的性質を異にする地すべり土について強度測定試験を行った.次に,残留係数を導入した三次元安定解析手法について検討し,提案した. 1.c-φ関係図において,c=37.5kN/m^2,φ=35.0°付近から正規圧密強度付近にまで及ぶ領域が強風化・破砕泥岩のピーク強度ゾーンとして設定された.正規圧密強度はc軸上のφ=23~30°の範囲にあり,残留強度はφ=9°~17°の範囲で与えられた.φ≦10°のような低い値は残留せん断面が鏡肌を呈するほどに発達した試料で得られた. 2.シルト・砂分が多く,粘土含有量が20%より少ない試料でもピークから残留への明瞭な強度逓減が認められた.強度逓減量は,配向性鉱物総量との関係において凸型変化を示した.地すべり土の応力~変位曲線は,含有される鉱物総量に基づいて4タイプに類別できた. 3.通常の地すべりの安定解析において、実験で得られるピーク強度,完全軟化強度(正規圧密強度)および残留強度の単独の適用は,安全率が過大または過小であると計算・評価してしまうため,すべり発生の事実が説明できない。提案された安定解析手法により,すべり面の平均強度定数が適切に算定され,二次元解析結果と比べてかなり小さいことが検証できた.また,本手法により,すべり時に動員されるピーク強度と残留強度の関与領域がすべり面全域で区分・表示できた.
要約(欧文):Strength measurement tests were carried out on landslide soils which showed a considerable variation in physical and mineralogical properties in order to obtain the their strength parameters c and φ for stability analysis. Then the three-dimensional stability analysis procedure, in which the residual factor was incorporated, was examined and proposed. The peak strength zone for strongly weathered and fractured mudstones was given by drawing the small area that reaches from the strength of c=37.5kN/m^2 and φ=35.0° close to the normally-consolidated strength in the c-φ figure. The parameters of normally-consolidated strength and residual strength were within the range of φ=23-30° and φ=9-17°, respectively. A fall in the strength from the peak to the residual state was clearly observed for the soil containing a large amount of silt and sand particles, and clay fraction below 20%. The variation of the strength reduction versus total contents of preferred-oriented clay minerals was expressed as a convex curve. Stress-displacement curves of landslide soils were classified into 4 types based on the total amount of minerals in soil. In the proposed analysis procedure, the average shear strength parameter acting along the slip surface was calculated precisely and was verified to be smaller than the parameter calculated by the two-dimensional analysis, and then each domain of both the peak and residual strengths mobilized at the slide could be expressed clearly on the whole slip surface area. This procedure will be helpful in rational and effective control works for landslide.
Type Local :研究報告書
Publisher :宜保清一
URI :http://hdl.handle.net/20.500.12000/14309
Appears in Collections:Research Report (Faculty of Agriculture)

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