Stability analysis in the large moved landslide

移動量の大きい浅層すべりと深層すべりの再発生時安定解析に残留強度および回復強度を適用し, 以下の知見を得た。(1)薛城鎮の三次すべりは層厚が8m∿10mの浅層すべりである。再発生時の安定解析に残留強度のみを適用した場合, 安全率がF_s=0.91となり, 斜面の安定度が過小に評価された。残留強度に加え, すべり面の低い土かぶり圧領域に回復強度を適用することによって安定度が合理的に評価できた。(2)亀の瀬地すべりの峠地区は峠ブロックと稲葉ブロックからなり,層厚が40m∿70mの深層すべりである。安定解析では, 高い土かぶり圧領域の全体に占める割合が極端に大きいため, 高い土かぶり圧領域の全体に占める割合が極端に大きいため, 残留強度のみによる安定解析を行い,合理的な結果を得た。峠ブロックは安全率はF_s=0.84となり, 稲葉ブロックによる抑止効果が約16%の安全率に相当していることが明らかになった。The large moved landslides are usually analysed assuming that the strength along the entire length of a slip surface droped to the residual value. However, in most cases, the safety factor is underestimated. The test of large displacement shear-re-consolidation-re-shear in the present experiment indicated the recovery from the residual strength after re-consolidation under the low normal stress such as 30kPa∿100kPa. The residual and recovered strength parameters were applied in the stability analysis for the shallow slide and deep slide of the large movement. The tertiary slide of the Xuechengzhen landslide is shallow, about 8m to 10m deep. Application of the residual strength to the stability analysis gave the safety factor of 0.91,which was underestimated. Higher reasonable strength parameters were obtained by using the recovered strength in the shallow slipsurface zone having low overburden pressure, and the residual strength in the deep slip-surface zone having high overburden pressure. The Toge unit in the Kamenose landeslide is deep, whilst, the thickness of the slide is 40m to 70m. Most part of the slip-surface zone is subjected to high overburden pressure. Thus, the stability analysis based on only the residual strength led to a result which was quite satisfactory