The Unifid Hardening Model Of Saturated Intact Loess Considering Soil Structure

Loess frequently shows special mechanics and engineering properties because of the existence of structure. In order to reflect structural variability of the saturated and intact loess, the deformation and strength characteristics of it are analyzed based on the indoor test.Soil structural quantitative parameters reflecting the effect of arrangement are further explored, research finding of the structure are applied to the unified hardening constitutive relation(UH model) analysis, its structural constitutive model is put forward. Main results as as follows:Firstly, the high pressure consolidation test,consolidated drained triaxial test and consolidated undrained triaxial test are conducted for saturated intact and reconstructed loess. Different springback stress has an impact on characteristics of compression deformation and on the compressibility index. The influence of structure on consolidation pressure and its change characteristic have been disscussed. Comparison about relationships of stress and strain, the volume strain, the strength and the characteristics of critical state under the condition of different stress pathes, structure influences law of stress-strain and strength characteristics.Secondly, according to the above experimental researches, the index of saturated intact loess structural characteristics is obtained. The deformation and strength characteristics of saturated intast loess are analyzed. Based on the analysis of the rules of the experiments,the parameters reflecting structure of soil are suggested, which is introduced into the UH model.The comparisions between the results of calculation and experiments show that the new UH model adapts a certain structural saturated intact loess(weak over-consolidated soils), and could describe the strain softening and strain hardening characteristics of the soil.The model is not only reasonable but also simple.All of the parameters in the model can be confirmed by general indoor tests, and the predicted results of model match well with the results of laboratory test, which indicates that the model reflects the stress-strain and strength characteristics of saturated intact loess very well, making it possible to be promoted and applied in actual engineering.