ANALYSIS OF THREE-DIMENSIONAL CONSOLIDATION OF UNSATURATED SOILS

This study extends the theory of three-dimensional consolidation to unsaturated soils and formulates the theory for finite element analysis by treating the pore water and pore air as a mixed pore fluid. This formulation considers variations in the permeability and compressibility of the mixed pore fluid with changes in the void ratio and degree of saturation. The compressibility of the mixed pore fluid is derived using Boyle's Law. An example of the settlement of a vertical drain is investigated and discussed; this example demonstrates that the numerical analysis theory is applicable and reliable. The results indicate that the rate of consolidation of unsaturated soils is clearly slower than that of saturated soils, the rate of dissipation of the pore fluid pressure is considerably 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 to obtain more reliable predictions of unsaturated soil consolidation.