液状化土の粘性抵抗に着目した浮上がり遠心模型実験
近年，液状化解析による液状化対策工の評価の必要性が高まっており，その評価に際しては，液状化地盤中の構造物の変位量が重要な指標となっている。液状化地盤の変形には液状化土の粘性抵抗が大きく影響することが既往の地盤流動の実験的研究から明らかになっているが，地盤振動との関係を調べた研究は見当たらない。そこで本研究では，液状化土の粘性抵抗に対する地盤の振動応答の影響要因について分析する目的で，粘性抵抗が支配的となる地中構造物の浮上がり遠心模型実験を行い，浮上がり挙動と液状化地盤の振動応答との関係を調べたところ，地盤振動に対して液状化土の粘性抵抗のせん断ひずみ速度依存性が成り立つ可能性が示された。
キーワード： 液状化土，粘性抵抗，浮上がり，遠心模型実験
＊１ 技術センター土木技術研究所地盤・岩盤研究室
Centrifuge Model Tests for Uplift of an Underground Structure Focusing on Viscosity of Liquefied Soil
Recent years have seen an increasing use of liquefaction analysis to evaluate the effectiveness of liquefaction countermeasures. One of the most important engineering parameters in such an evaluation is the amount of displacement of a structure in liquefied ground. Research into the lateral spread caused by liquefaction has revealed that viscosity of liquefied soil greatly influences deformation of liquefied ground. However, the relationship between viscosity of liquefied soil and ground shaking has not been studied. To examine this relationship, we conducted a centrifuge model test for uplift of an underground structure in which viscosity was the dominant factor. And then, we investigated the relationship between the uplift of the structure and the ground shaking after liquefaction. The results show that the viscosity of the liquefied soil probably depends upon the shear strain rate produced by the ground shaking.
Keywords: liquefied soil, viscosity, uplift, centrifuge model test
*1 Soil and Rock Engineering Research Section, Civil Engineering Research Institute, Technology Center
