Enhanced Strain-Softening Model from Cyclic Full-Flow Penetration Tests

Abstract

This paper presents a systematic approach for relating fundamental (soil element) strength-degradation models with cyclic full-flow penetration tests. The approach is then employed to enhance the commonly-used exponential strain-softening model by adding a parameter that regulates the slope of degradation. Using the developed methodology, a new relationship between ξ95 and N95 (the shear strain and cycle number associated with 95% degradation in strength and penetration resistance, respectively) is established for the enhanced strain-softening model. The additional parameter of the enhanced model is optimized against various cyclic field test results and found to be roughly constant. It is demonstrated that the new model independently reproduces the field test results when introduced into advanced numerical analyses of cyclic penetration tests.