| There are more and more filled engineer in loess area,which is made up of the unsaturated remolded loess.Therefore,It is of great theoretical significance to analyze the deformation and strength stability of loess by doing the true triaxial test on strength deformation characteristics of unsaturated remolded loess under the condition of infiltration moistening complex stress.In this paper,matrix suction axis translation technique of unsaturated soil and the true triaxial tests are used to study on the variation of stress and strain of the Loess,shear yield strength and shear failure strength with different matric suction in the constant middle principal stress ratio and the mean spherical.The results and conclusions were got as following:1.The unsaturated remolded loess samples were made by ring knife method with different moisture content.The pore gas pressure and pore water pressure are controlled by unsaturated soil consolidation apparatus to test the moisture content of unsaturated soil samples under different matric suction and the soil water characteristic curve was obtained.2.The true three-axis samples were prepared with different water content by pressure method.The matric suctions were obtained according to the soil water characteristic curve.The axis translation technique was used to control the constant matric suction value under 50 kPa,80kPa,120 kPa,200kPa.The samples were consolidated under 300kPa?400kPa?500kPa?600kPa net cell pressure.And then control the b value under 0,0.15,0.5,0.7,0.9,and 1.The true three axial shear tests are carried out with constant matric suction and net cell stress,and the corresponding experimental results are obtained.3.Based on the curve between the bulk strain and effective stress ratio,the linear variation of bulk strain in the initial shear segment and the development process of the nonlinear change from the yield to the obvious increase of the bulk strain are analysed.The effective stress ratio of shear yield is determined.The relationship between the generalized shear stress and the mean effective stress of the shear yield state in the plane of the meridional plane with different principal stress ratios is analyzed,which is approximately linear and pass through the origin.4.Analyzed the rule of the change in ratio of major principal stress and minor principal stress?the ratio of intermediate principal stress and minor principal stress?the volumetric strain respectively with the major principal strain?intermediate principal strain under some specific matrix suction and average stress conditions in the different shearing process.it shows that the unsaturated loess have shrinkage properties in volume under the suction between 50 kpa to 200 kpa but themean net net stress between 300 kpa to 600 kpa.The intermediate principal strain shows stretch deformation when the b in 0-0.15 and it shows compress deformation when the b in 0.5-1.5.Under different matrix suction and mean effective stress condition,the curves of the generalized shear stress and shear strain for the unsaturated soil shows that the shear strength of shear failure state gradually decreased with the b value increase.The shear strength in different meridional plane shows the linear growth tend with the mean effective stress change.The shear strength under different effective stress state in ? plane approximate accord with Matsuoka-Nakai strength criterion. |
PDF Full Text Request