Application of High Power Vibroflotation Gravel Pile in the Treatment of Liquefied Foundation

A subway depot in Beijing covers an area of about 20 hectares. The ②₅ layers of saturated silty fine sand within 20 m depth of the site will produce liquefaction. The liquefaction grade is slight to medium (locally serious), and the thickness of liquefiable layer is 5 m. In the rail transit project, the high-power 100 kW vibroflotation gravel pile is used to treat the liquefied foundation for the first time. The test results show that the vibroflotation gravel pile with large pile spacing not only meets the design requirements of foundation liquefaction treatment, but also creates conditions for the in-situ construction of cast-in-place pile in the later stage. At the same time, the combination of high-power vibroflotation gravel pile and CFG pile foundation treatment is applied to the site, which solves the problems of foundation liquefaction and post construction settlement of track subgrade.