Modification In SFG Model And Researches

So far the theory basis of soil mechanics is still far from consummate and still in a semi-theoretical, semi-empirical stage. It is the most important task for researchers to develop a unified theoretical basis for soil mechanics. The multiphase porous medium theory, developed from 1960s, provides a theoretical basis for unsaturated soil mechanics. Unsaturated soils are three phase porous media, consisting of soil skeleton and pores, with water and gas filled in the pores. Comparing with saturated soils, unsaturated soils have more complex properties because of existence of gas in pores and existing of suction. Owing to the complexity of unsaturated soils, it is difficult to predict the deformation and strength behavior of unsaturated soil uniquely. In this thesis, taking the principle of generalized effective stress and continuous SWCC model which can reflect the influence of void ratio on SWCC, SFG model is modified and a new model is proposed. Some research data are used for comparing with the new model by MATLAB. Modified SFG model can not only reflect some advantages which are owned to SFG model, such as modeling slurry soils, the smooth transition between saturated and unsaturated soil states, the change of the yield stress with soil suction and so on, but also reflect the influence of change of void ratio on degree of saturation. Modified SFG model illustrates that the yield surface relate with the suction as well as the degree of saturation and current void ratio. Additionally, modified SFG model can more perfectly simulate the relationship between the degree of saturation and the suction because of using continuous SWCC model rather than SFG model, which takes double-line SWCC model.