Shear Strength of Unsaturated Soils - Unsaturated Soil Mechanics in Engineering Practice - page 561

Figure 11.52 Typical stress path followed during consolidated undrained test.

Figure 11.53 Stress conditions at various stages of undrained triaxial compression test.

the application of the confining pressure; however, the stress
state will not be known unless the pore fluid pressures are
measured.
The soil specimen is sheared by applying an axial stress
σ 1 −

pore-water pressures. The excess pore pressures can be
related to the deviator stress by the D pore pressure
parameters for triaxial loading conditions provided the pore
fluid pressures are measured. Generally, the pore pressures
are not measured during an undrained test. Undrained test
results are commonly used in conjunction with a total stress

σ 3 until failure is reached. Undrained loading during
shear causes a further change in the excess pore-air and