Changsha Typical Silty Clay Triaxial Test And The Constitutive Model

On the basis of analysis of the research achievements in the past, combined with the silty clay in Changsha Area, in this paper author has analyzed the stress-strain and deformation characteristics of the silty clay in Changsha Area by a series of methods including laboratory tests and field tests, theoretical analysis and numerical simulation, and based on the Duncan-Chang constitutive model, a modified nonlinear elastic constitutive model has been established. Some useful results have been get after those.Firstly, a series of triaxial tests considering some different stress pathes for silty clay in Changsha area have been performed, which the deformation characteristics and the intension characteristics have been revealed. The test results show the main stress-strain deformation behaviors as hardening, dilation and obvious linear interval. The stress path has obvious influence on the total stress shear strength indexes, but almost no influence on the effective shear strength indexes.Secondly, based on the test results, the stress-strain relationship curves have been normalized, and the Duncan-Chang constitutive model has been discussed. So a modified nonlinear elastic constitutive model for silty clay in Changsha area has been derivated, and all the model parameters have been determined. It is shown that the model in this paper can be included in the nonlinear and dilatancy(shrinkage) properties, and the effects of different consolidation pressure and the second main stress.Thirdly, the modified nonlinear elastic constitutive model for silty clay in Changsha area has been applied to the analysis of deep excavation project, the validity of proposed constitutive model is confirmed by comparisons of the calculated results and the observed results.The research results can guide good directive significance to the area in Changsha and engineering construction in the area similar to the soil layer .