Critical state constitutive model of sand with shear hardening

Based on the framework of critical state soil mechanics,a new Cam-type sand model,being applicable to monotonic loading,is proposed.The model combines the concept of state-dependent dilatancy and shear strain hardening rule.Reverse bullet-shaped yielding surface is adopted.Not the volumetic strain hardening in Cam-clay model,but the shear strain hardening rule is used and a new hardening equation is given.The state parameter concept is incorporated in Rowe’s stress dilatancy equation.The model accounts for the dependence of dilatancy on the stress state and the material internal state.A single set of model constants,once calibrated,can simulate stress-strain response under different initial void ratios and different confining pressures.The model is validated by comparing the predicted results with triaxial test results.