Abstract: By the application of computer digital image measuring technique to sample deformation measurement of soil static triaxial test, non-contact measuring of soil specimen deformation was realized. For Nanning saturated fine sand, loose and dense samples were prepared respectively by dry-rapping method and wet-tamping method controlling the different initial moisture content. Combining the digital image measuring technique with traditional triaxial deformation measuring method, consolidation drained shear tests were made under different confining pressures. The influence of sample preparation methods, initial moisture content, degree of compaction and consolidation pressure on relation of stress and strain and different of tangent modulus 5 parameters of Duncan-Chang model by means with the two measurement methods are researched. The test results show that the forms of sample shear failure are decided by the sample preparation method, initial water content, density and confining pressure; and the relations between stress and strain are affected also. There were differences of axial strain and deviator stress by image measuring and traditional triaxial cause because the different shear failure forms and the location of shear band. Duncan-Chang model 5 parameters are affected not only by the sample preparation method, initial moisture content and, density, but also by the methods of measurement.

Key words: digital image measuring, Nanning saturated fine sand, drained shear test, sample preparation method, tangent modulus parameter