Simplified method for predicating consolidation settlement of soft ground improved by floating soil-cement column

GONG Xiao-nan(龚晓南)^{1, 2}, TIAN Xiao-jun(田效军)^{1, 2}, HU Wen-tao(胡文韬)³

(1. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Department of Civil Engineering,
Zhejiang University, Hangzhou 310058, China;
2. Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China;
3. School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China)

Abstract:A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consolidation model and equal strain assumption, the governing equation was derived for the consolidation of clayey subsoil reinforced by soil-cement column. By modifying the boundary condition of the interface between the improved layer and underlying layer on seepage and pore-water pressure, the analytical solution of consolidation of soft ground improved by floating soil-cement column was developed under depth-dependent ramp load. The results of the parameter analysis of consolidation behavior show that the consolidation rate is closely related with the depth replacement ratio by the column and the permeability of upper layer. The influence of column-soil constrained modulus ratio and radius ratio of the influence zone to the column on consolidation is also affected by depth replacement ratio. The column-soil total stress ratio increases with time and approaches the final value accompanied with the dissipation of excess pore water pressure.

Key words:axisymmetric consolidation model; floating soil-cement column; consolidation; depth-dependent ramp load; analytical solution