Influence Of Stress Path On Deformation And Strength Characteristics Of Saturated Intact Loess

Different stress paths may be undergone by soil mass in the construction of geo-technical engineering. The soil property parameters determined by conventional triaxial test are adopted in many geo-engineering design, the influence of stress paths is not considered on which. But research results show that the stress-strain relationship of soil is evidently influenced by stress paths. So that, the research on deformation and strength characteristics of soil under different stress paths is very important in theory and practice. But at present, there is a few studies on deformation and strength characteristics of intact loess soil under different stress paths.In this paper, the influence of stress paths on deformation and strength characteristics of saturated intact loess of LangLing has been studied. First, many triaxial shear tests of consolidated (isotropic consolidation and K0 consolidation ) undrainage and that of consolidated ( K0 consolidation ) drainage were conducted under three kind stress paths including axial loading and radial unloading( LU), axial unloading and radial loading (UL) and axial unloading and radial unloading (UU). Secondly,a uniform expression of relationship between initial tangent modulus (or shear strength) and stress paths under different consolidation confining pressure was put forward, and the method determining the parameters of stress-strain relationship of saturated intact loess was proposed under different stress paths on the basis of analyzing influences of stress paths on stress-strain and shear strength characteristics of saturated intact loess under both drainage and undrainage, and pore water pressure equation of saturated intact loess was suggested under different stress paths, at the same time, some disciplinary knowledges to relationship between stress path and pore water pressure as well as effective stress paths have been obtained on the basis of analyzing influence of stress paths on pore water pressure and effective stress paths under undrainage condition. Some disciplinary knowledges to relationship between stress path and volumetric strain have been obtained on the basis of analyzing influence of stress paths on the volumetric strain developing protery under drainage condition. Lastly,According to results of triaxial shear testof saturated intact loess under different stress paths, the feasibility of applying the linear relationships between ratio of shear /normal stress and ratio of normal / shear strain increment or ratio of normal / shears train was verified at the max strength plane and the Extend SMP under both drainage and undrainage. It is showed that from the verification results, the linear relationships between ratio of shear /normal stress and ratio of normal / shear strain increment or ratio of normal / shears train exist under both drainage and undrainage, but parameters of the linear relationships can be influenced by drainage condition and stress plane as well as mode of failure.