An experimental study on dynamic constitutive model of clay under multiaxial compression

Abstract
The quasi-static mechanical behaviors of the clay under multiaxial compression were obtained with the unconsolidated and undrained (UU) test with confining pressure from 100kPa to 400kPa. Results of the quasi-static experiments show that the yield strength of clay increased with the confining pressure. In addition, an improved split Hopkinson pressure bar (SHPB) method with passive confining pressure was used to study the dynamic properties of the unsaturated clay at various strain rates. Experimental results show that both modulus of elasticity and yield strength of the clay were sensitive to strain rates. The confining pressures of the specimens were also obtained from the dynamic tests. The quasi-static and dynamic stress-strain behaviors of the clay under confinement exhibited an elastic-plastic-like response. Based on the results of both dynamic and quasi-static tests, a phenomenological elastic-plastic type of material model was employed to describe the strain-rate-dependent properties of the clay under tri-axial state of stress, which agreed well with the experimental results.