Fig. 6.5. (a) Schematic of laboratory triaxial set-up (b) Stress system in soils in triaxial test

The normal load, to induce deviatric stress, is then applied to generate shear stresses in soil sample. The dissipation of excess pore water pressures can be allowed depending on the test condition. The volume change in the soil can indirectly be measured from the measurement of volume of water leaving the soil sample during the excess pore water pressure dissipation. The effective principle stresses at failure can be used to determine the shear strength parameters.