Drained cyclic behavior of sand with fabric dependence

The behavior of sand is characterized by dilatancy, an increase in overall volume as particles move over each other when the sand assembly is subjecte d to shear stresses. A stress-dilatancy model for sand in the cyclic loadin g regime, taking into account microstructural changes, is presented. The mo del is subsequently integrated into a constitutive model based on hypoplast icity so as to accurately calculate volume changes induced by fabric and di latancy changes during cyclic loading. Furthermore, it is assumed that fabr ic evolution is a function of the ratio of deviatoric to mean principal str ess. Some numerical examples that capture the effect of fabric changes on t he drained cyclic behavior of sand are presented. Among others, it is found that initial fabric can drastically alter both the dilatancy response and net volume change at shakedown conditions even though the initial void rati o and confining pressure are kept unchanged. The void ratio here is defined as the volume of voids to that of solids.