Analytical study on the consolidation of soft soil under vacuum preloading combined with fill surcharge

Costal belts are normally composed of highly compressible soils with very low bearing capacity. To avoid excessive settlement of soft soils, vacuum preloading with combination of fill surcharge is frequently adopted in field to accelerate the consolidation progress. This paper presents analytical derivations of excess pore-water pressure and average degree of consolidation distributions of soft soil layers under the effect of both vacuum preloading and fill surcharge. Typical considerations in these analytical derivations involve: (a) both vertical and horizontal drainage conditions; (b) well resistance and smear effect; and (c) three assumed distributions of coefficient of permeability in the smear zone. A case study is presented for discussion of the effect of different parameters. The present analytical results are found to agree fairly well with the measured settlement data of Huanghua Port in China. The analytical solutions and the related comparisons present a better understanding of the significance of different parameters.