Total Stress Analysis. The total stress analysis uses the undrained shear strength of the plastic soil.
The undrained shear strength su could be determined from field tests, such as the vane shear test
(VST), or in the laboratory from unconfined compression tests. If the undrained shear strength is
approximately constant with depth, then su = c and f = 0 for Eqs. 6.1 and 6.5.