降雨による砂質斜面崩壊発生時の過剰間隙水圧と崩土の運動に関する水路実験研究 [in Japanese] Study on the Excess Pore Pressure Generation at Failure and the Resulting Movement of Sandy Slope in Flume Test by Rainfall [in Japanese]
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本研究は, 水槽を用い, 降雨による斜面崩壊実験を行った結果, 以下のことが明らかになった: (1) 過剰間隙水圧は崩壊後のせん断中に発生したもので, 斜面崩壊の結果である; (2) 崩壊時, 斜面土層内の応力の変化を計測した結果, 自然の排水状態時でも完全な液状化が発生しうる; (3) 水槽の勾配, 試験材料, そして初期密度の違いは過剰間隙水圧の発生, 破壊モード, そして崩土の運動に大きく影響する。
By using a small flume, a series of tests has been carried out to trigger rainfall-induced-slope failure. The detailed monitoring of excess pore pressure and the soil displacement revealed that a high excess pore pressure was generated not before the failure, but during the subsequent motion after the failure. The variation of shear stress, normal stress and pore pressure during failure shows that approximately full liquefaction failure could be initiated even when the soil was in naturally drained state in slopes. By using silica sand no. 7 (<I>D</I><SUB>50</SUB> = 0.14 mm) and no.8 (<I>D</I><SUB>50</SUB> = 0.0576 mm) and changing the samples' initial dry density and flume angle (20 and 30 degrees), the effects of grain size, initial density and flume angle on the generated pore pressure and fail-ure mode were analyzed. Results from tests of different initial densities show that there is an optimal density index for excess pore-pressure generation. Moreover, observed failure phenomena show that the failure mode was dependent greatly on the grain size and flume angle. In fact, flowslides were initiated in the tests on finer silica sand (no. 8) when the flume angle was 30 degrees, while in other tests, just retrogressive sliding ap-peared.
Landslides 37(2), 40-47, 2000-09-15
The Japan Landslide Society