ANALYSIS OF THREE-DIMENSIONAL CONSOLIDATION OF UNSATURATED SOILS

Abstract

This study extends the theory of three-dimensional consolidation to unsaturated soilsand formulates the theory for finite element analysis by treating the pore water and pore air as amixed pore fluid. This formulation considers variations in the permeability and compressibility ofthe mixed pore fluid with changes in the void ratio and degree of saturation. The compressibility ofthe mixed pore fluid is derived using Boyle's Law. An example of the settlement of a verticaldrain is investigated and discussed; this example demonstrates that the numerical analysis theory isapplicable and reliable. The results indicate that the rate of consolidation of unsaturated soils isclearly slower than that of saturated soils, the rate of dissipation of the pore fluid pressure isconsiderably slower, and the permeability of the mixed pore fluid decrease during consolidation.This theory is applicable to unsaturated soils with high degrees of saturation and can be used toobtain more reliable predictions of unsaturated soil consolidation.