Constitutive Modeling of Loose Sands under Various Stress Paths

Abstract

Developing reliable and versatile constitutive models for geomaterials has been a challenging task for nonlinear finite-element analysis of geotechnical engineering systems. This paper is mainly concerned with the elastoplastic constitutive relationship of unbound granular materials under various stress paths. The fuzzy set plasticity theory has been developed to account for the nonlinear soil stress-strain behavior. The theory in many ways resembles the bounding surface plasticity, where the plastic modulus is a function of the distance between the current and image stress states in the stress space. Based on the concept of fuzzy set theory in mathematics, a membership function whose value ranges from 1 and 0 is introduced to specify the plastic modulus at a given stress state. Hollow cylinder and cubical test results on Hostun sand from the CASE database were selected to assess the fuzzy set plasticity model. The numerical results showed that the fuzzy set model is capable of mimicking and simulating the nonlinear behavior of loose sands under various loading paths.