Simplified computation of deformation for unsaturated soil under compression loads

The consolidation of unsaturated soil was simplified into two stages.During the first stage,the water and air in the pores could not be drained immediately and could support the loads together with soil skeleton,and the pore pressure of water and air would rise.The soil was compressed immediately and the suction was reduced because of the compression of the air in the pore.During the second stage,the excess pore pressure was dissipated under the constant loads.Water and air in the pores could be regarded as a mixed fluid with high degree of saturation.Balanced differential equations and continuous equations of pore fluid were established regarding the compressibility of the mixed fluid in the pores.Then the effective stress and mixed fluid pressure could be computed.It was shown by a numerical example that the effective stress,pore pressure of mixed fluid and pore-water pressure increased and the suction decreased during the process of loading,and the pore pressure of mixed fluid and the pore-water pressure continued to increase after the completion of loading,and the majority of deformation occurred during the compression stage.All of these were similar to the monitored results in the process of embankment construction.Therefore,the approach was reasonable and very important to promote practical computation of consolidation deformation.