地下水揚水に伴う地盤沈下時のパイルドラフト敷設効果

Abstract

The behavior of piled raft foundations on natural deposited soils subjected to ground subsidence due to dewatering is analyzed in this paper. A three-dimensional finite element model considering the soil-water coupled problem has been developed. In this analysis the piled raft and the soil are modeled as an elastic material and a two-phase elasto-plastic material, respectively. It can be deduced from the calculations that changes in axial forces and bending moments acting on the piles of piled raft foundations are lower than these corresponding to bearing pile foundations. This suggests that piled raft foundations are more effective for the reduction of negative skin frictions on piles. Piled rafts with longer piles can reduce the settlement due to dewatering in case that delayed consolidation does not occur. If the toes of piles locate in the layer which causes delayed consolidation, the settlement of piled rafts would be larger than that corresponding to raft foundations