There are several differences between the direct shear test and triaxial shear Test. Direct test is the simplest and oldest test whereas triaxial is much more complicated. In direct test shear failure is predetermined while in triaxial shear failure is not predetermined. Consolidation and drainage of sample is relatively fast in direct shear test while it takes longer time in the triaxial test. The result of the triaxial test is more accurate as it gives the results of the particular layer of the soil. So, as an engineer I would prefer to do the triaxial shear test. -Deviator stress is the difference between the major and minor principal stresses in a triaxial test. Confining stress is the actual stress that is applied to the soil sample. As the confining pressure increases the deviatoric stress also increases because a when the more pressure is applied to the specimen, it has higher chances to sheared fast resulting the increase of deviatoric stress. When the pressure is acted in the sample, the diameter of the soil doesn't remain constant. Diameter of the sample trend to increase and so we use the correction factor and get the corrected area. When we have a higher