Effect of Strain-Softening in Interpretation of Laboratory Compression Tests
The interpretation of post-peak stress-strain relationship from laboratory compression tests performed on strain-softening clay specimens under undrained condition is considered. Since failure of a strain-softening material is accompanied by strain localization, the post-peak stress and strain distributions will be highly inhomogeneous. Standard interpretation techniques will then overestimate the rate of softening significantly, i.e. the steepness of the post-peak stress-strain curve is overestimated. Finite element analyses of a biaxial compression test are used to demonstrate this effect by simulation. The effect of strain-softening is accounted for by an elasto-plastic strain softening material model within the concept of total stresses, using the Tresca yield criterion. Some comments are also made concerning the severe mesh dependency associated with the use of a strain-softening material model.
KeywordsPeak Strength Biaxial Test Plane Strain Compression Peak Shear Strength Plastic Shear Strain
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