Abstract: The definition of strain-softening and strain-hardening is studied from the plastic work of constitutive curve. The relation between strain-softening and damage is analyzed by introducing the micro-structural “self-consistent” rule in mechanics of materials. In geotechnical engineering, the constitutive model for strain-softening medium is mostly described by negative exponent distribution or Weibull distribution. In view of this, the model for solving the parameters of constitutive formula for strain-softening media under Weibull distribution is analyzed and its parameter characteristics and the adaptability of the constitutive curve are also discussed.

Key words: Rock and soil mechanics, Strain-softening, Constitutive model, Weibull's distribution, Self-consistent rule, Prameter model