Experimental Study On Strength And Deformation Characteristics Of Unsaturated High Liquid Limit Red Clay In South

The stress-strain curve is an important index to describe the strength and deformation characteristic of soil,this paper takes Hunan province Chenzhou section of Xiamen Chengdu Expressway to the unsaturated red clay with high liquid limit as the research object,combined with the basic theory of non saturated soil at home and abroad,through indoor three drained triaxial test of red clay and net confining the deformation characteristics under different strength in different matrix suction and high liquid limit;the introduction of Duncan Chang model,solving Duncan Chang model parameters,and the tangent Poisson ratio is corrected,and the red clay for stress-strain relationship of the research on the high liquid on the basis of the improved model.The main contents of this paper are as follows:(1)On the basis of the three axis translation technique,the drained triaxial test using GDS unsaturated triaxial apparatus three stress path controlled suction and net confining pressure,through the test results,a detailed analysis of red clay under different matric suction and net confining pressure under different failure modes of high liquid limit,stress strain the relationship between the radial strain and volumetric strain changes with the axial strain.(2)Of different matric suction and net confining pressure effect on the high liquid limit of red clay strength,obtained high liquid limit red clay shear strength parameters;analysis of matrix suction on the cohesion,influence of internal friction angle is deduced;the expression of high liquid limit red clay consolidation undrained shear strength test results show that,Fredlund,the two stress variable strength formula can express the red clay in the nonlinear stress strain relationship.(3)The stress-strain relationship is introduced based on the Duncan model,calculate the Duncan Chang model parameters,the calculation of Duncan Chang model tangent modulus of deformation,failure ratio,Poisson’s ratio,tangent bulk modulus,study with matrix suction and net confining pressure.The variation of these parameters.(4)The study found in the E-? model,the calculation results of the tangent Poisson ratio error is large,it is difficult to reflect the change characteristics of soil body,according to the Poisson’s ratio is modified,the relation curve of radial strain and axial strain are divided into two sections,respectively,with two parabolic and linear form fitting,calculate the tangent Poisson ratio parameters the function expression of the tangent Poisson ratio after correction is proposed.The new model can reflect the discovery of southern Hunan non deformation characteristics of saturated red clay with high liquid limit more than the model.