The Structural Property Studies Of The Unsaturated Loess And Its Elasto-Plastic Model Studies

The loess is one kind of typical structural soil, its special structural property and sensitive property directly affects the mechanical properties of the unsaturated loess. In our country, the loess mainly distributes in the mid-west area. Along with the strategy of the west development implements, many basic constructions need to carry on in the loess area, Therefore the loess further research is very urgent, Especially the structural research of loess is the main content about loess mechanics research this century .In this paper, the basic nature,the structural property research importance and the present situation about the loess are introduced firstly, then by means of conventional tri-axial test and equal stress-ratio pressure test of intact loess sample with different initial water content and remolded loess sample with different initial water content, thoroughly analyzed and discussed the stress-strain characteristic and the structural change characteristic of unsaturated loess under two kinds of test conditions,and defined the structural parameter of unsaturated loess according to the result that the predecessor had researched previously, and confirmed the sensitivity,the stability and the reliability of the structural parameter of intact loess. The result indicates, the loess structural property mainly influenced by the initial water content,the stress condition and dry density and so on, these factor decide the loess stress strain relations and the loess destructive form.Through add the structural parameter to the stress-strain relations of the conventional tri-axial test and equal stress-ratio pressure test, obtains the constitutive stress strain relations of unsaturated loess under two kinds of test conditions. The result indicates, the form of stress strain relations adding the structural parameter are converted into the hyperbolic form, and could be calculated with the expression of hyperbola.Finally, based on the experimental data of above test, an elasto-plastic model which can simulate the strain softening and strain hardening is presented. and carried on the comparison analysis to the test result and the model computed result.