Constitutive Model Of Clay And Frozen Soil Under Impact Loading

The constitutive model of clay and frozen soil under impact loading is investigated.The main work and key developments in the study are given as follows:First, to obtain the static material parameters of clay, an unconfined compressionstrength test was carried out on the triaxial compression test machine. Then the dynamicproperties of clay were determined using the SHPB system at a range of strain rates at500~1200s1. Experimental results showed that clay is strain rate dependent.To study the mechanical behaviors of clay, using the material elastic-plastic theory, aquasi-static elastic-plastic constitutive model was established. Combined with the damagemechanics, the damage was defined and the evolution equation of damage was given. Inplasticity, a modified Mohr-Coulomb yield function was adopted and the strain rate effectwas considered. At last, based on the effective stress principle in soil mechanics, the porewater pressure and pore air pressure was added in.By means of SHPB, the dynamic properties of frozen soil were studied at a range ofstrain rates at300~1200in the temperature of-3℃、-8℃、-13℃、-17℃、-23℃and-28℃.Then the stress-strain curves were obtained. Experimental results showed that frozen soil isstrain rate dependent. The peak stress increased with the strain rate.Based on the micromechanics analysis, frozen soil is considered as two distinct phasecomposites, soil particles and ice. And the soil particles and ice were assumed to behomogeneous and isotropic. Then the equivalent modulus of elasticity and the equivalentPoisson’s ratio subjected to axial loading were investigated respectively. In this chapter, anisotropic hardening constitutive model is presented to study the behavior of frozen soilunder impact loading. In plasticity, a modified Drucker-Prager yield function is adopted.Finally, the damage in frozen soil was defined and the evolution equation of damage wasgiven.Finally, the parameters of the constitutive model of clay and frozen soil are determined.Compared the prediction curves with the experimental curves, they agreed with each otherwell.