| Fibrous and high organic peat、 which is much distributed in Hokkaido、 Japan、 is very soft and problematic ground. The vacuum preloading method is a countermeasure for peaty soft ground in which negative pressure is applied to the ground using vacuum pumps and prefabricated vertical drains. Test fill work was conducted in soft ground consisting of peat、 organic clay and clay to clear effect on reduction in secondary consolidation of the vacuum preloading method. In addition to the test construction、 the finite element analysis using a visco-plastic constitutive equation was conducted to evaluate relationship the over consolidation ratio OCR and reduction ratio of secondary consolidation of peat.[*]This paper presents that the results of the test fill work and the FE analysis as for the vacuum preloading applied to peat ground. The following matters were clarified as a result:[*]1) Negative pressure、 which was applied during pump operation、 was unloaded after the stopping of pumps and caused over consolidation of the ground.[*]2) The relationship between the OCR and the reduction rate of secondary consolidation R describes a form close to a hyperbola with the maximum curvature near an OCR of 1.3.[*]3) Secondary consolidation can be controlled by vacuum preloading、 and the amount of settlement can be predicted using the relationship between the OCR and R. |
