Prediction of Consolidation of Soft Soil Layers due to Road Embankment

BIOTの圧密理論にもとづく弾性圧密解析の概要を紹介し、軟弱地盤の盛土にともなう挙動解析に適用した。圧密解析には、GHABOUSSI and WILSONにより定式化された有限要素法を用いた。まず、不飽和状態の地盤まで考慮できるBIOTの圧密理論の特徴を紹介し、1次元および2次元圧密問題の理論解と比較することにより、有限要素法を用いた圧密解析法の実務性を調べた。次いで軟弱地盤に適用し、道路盛土の新設にともなう圧密沈下挙動の特徴を調べた。地盤は軟弱な粘性土で構成され、解析に必要な材料特性は、ボーリング試料の圧密試験より決定した。絶対量は小さいものの、長期にわたって圧密変形が継続することを示した。A numerical analysis of linear consolidation was introduced to investigate deformation of soft soil layers due to embankment on the ground surface. Theoretical equations of the numerical analysis were derived based on the BIOT’s theory of consolidation, and were formalized into a finite element equation according to the procedure proposed by GHABOUSSI and WILSON. Firstly the BIOT’s theory of consolidation was described briefly. An accuracy of the finite element analysis was examined by comparing the calculated results with the theoretical solutions in one-dimensional and two-dimensional consolidation of soil. Then the finite element analysis was applied to predict the consolidation of the soft soil on which a new embankment of a road was to be constructed. The soil was layered by soft clay soils and volcanic clay. Soil parameters that were required in the finite element analysis were determined by laboratory consolidation tests of soil sampled during boring tests. It was predicted that a small amount of consolidation of soil would be continued during some years