Experimental Study On Equivalent Consolidation Deformation Analysis Method Of Unsaturated Soil

The consolidation deformation characteristics of unsaturated soil and its analysis methods are key issues in the field of soil mechanics. Because of unsaturated soil being three phases and porous media, not only interaction between solid phase, liquid phase and gaseous phase, the mechanical efficiency from complicated shrinkable film but also morphological changing and chemical change in soluble mineral property are being. So, It is not enough to only build an association between solid phase, liquid phase, gaseous phase and shrinkable film by suction characteristic quantity in the study on mechanical behavior of unsaturated soils. Weaknesses do exist in ideas of consolidation settlement of unsaturated soil with so much hypotheses on consolidation analytic theory of unsaturated soil whether based on single variables or double variables. This paper raises a new method by dropping the traditional methods which researching consolidation settlement of unsaturated soil based on single variables or double variables. The solid phase, liquid phase, gaseous phase, shrinkable film and mineral components behavior apparent effect are considered as equivalent skeleton phase and fluid phase. Equivalent skeleton phase is capable of stress resistance and shear performance. Equivalent fluid phase only has stress resistance. It can move being relative to skeleton phase. Equivalent skeleton phase includes particle skeleton, shrinkable film reinforcement effect, soluble mineral property cementation and electric stress effect. Equivalent fluid phase includes pore water and pore air which at shrinkable film both sides. Complex multiphase of unsaturated soil is equaled equivalent skeleton phase and fluid phase. So the complex consolidation of unsaturated soil can be solved by two-phase analysis method. Equivalent skeleton phase stress equals to pressure on soil unit body when consolidation settlement keeps stable. Equivalent fluid phase, being relative to skeleton phase, moves under a function of the pressure gradient with dispersion of fluid pressure. Based on this idea, equivalent skeleton phase stress and equivalent fluid phase pressure can be obtained from stress-strain behavior of unsaturated soils. So, we bring forward a method of determination of equivalent skeleton phase stress andequivalent fluid phase stress.Lots of consolidation experiments of unsaturated soil indicates that instantaneous compression deformation of unsaturated soil can not be neglected. Compression deformation includes instantaneous compression deformation, consolidation settlement and rheologic deformation. Confirm equivalent skeleton phase stress in the process of instantaneous compression deformation and the variation regularity of equivalent skeleton phase stress and equivalent fluid phase stress in the process of consolidation based on instantaneous compression deformation and compression deformation. Increasing of compression deformation leads to high equivalent skeleton phase stress. Increasing of compression deformation leads to low equivalent fluid phase stress. Under the additional load, compression deformation and instantaneous deformation must be concurrence.This paper brings forward equivalent consolidation physics-model of unsaturated soil based on load transfer mechanism and the development and changes of equivalent skeleton phase stress and equivalent fluid phase stress. There are instantaneous compression deformation and equivalent fluid phase stress in unsaturated soil as soon as applying load. This paper analyses instantaneous compression deformation characteristics and the change rule of consolidation coefficient based on uniaxial compressive consolidation test. There is linear variation rule between volume change and equivalent fluid phase stress.This paper sets up one dimension equivalent concretion analysis method. The method and instantaneous compression deformation analysis can be used to describe the developing stage of concretion deformation of unsaturated soil foundation. The computed result to heavy-thickness specimen (h=14cm) is in good agreement with that of the experiments.This paper expresses the results are the base for the further study equivalent consolidation theory.