Quasi steady state in Triaxial CIU tests

[Geotech351]

I have received some triaxial CIU test results, and the stress path indicates that the samples contracted until 7 to 10% strain, then started to dilate. The deviator stress continued to increase even after the pore pressure reached its peak.

Is it reasonable to consider peak effective shear stresses, even when the material contracts at relatively high strains (7 to 10%)? Or would the use of undrained parameters be more justified under short-term loading conditions?

I’m also wondering if using reduced parameters at the stage when the phase transformation occurs might be a better approach.

Please let me know your thoughts.