CHARACTERISTICS OF STRESS-STRAIN CURVES AND CONVERGENCE PHENOMENON OF FROZEN SOIL UNDER DYNAMIC LOADING

Based on the systemic impact loading experiments of frozen soil, this research analyzes the characteristics of the dynamic stress-strain curves and the necessity of such phenomenon in split Hopkinson pressure bar experiments. And a convergence phenomenon of strain is concluded from the experiment results. It shows that parameters such as strain rate, freezing temperature and initial moisture content have effects on the dynamic stress-strain curve. The occurrence prerequisite of strain convergence phenomenon is an identical strain rate but not on the freezing temperature and initial moisture content. The research suggests that thermal damage and crack damage take an important role in the dynamic stress-strain curve and in the strain convergence phenomenon of frozen soil. Crack damage is one common form in each material, which contributes to the shape of stress-strain curve immediately. Thermal damage describes the effects of transient temperature rising, which leads to metabolic ice ratio and is an important element for the dynamic properties of frozen soil. Moreover, the loading process of split Hopkinson pressure bar experiment is another important factor of strain convergence phenomenon, which determines the convergence position. Generally speaking, the convergence phenomenon is a peculiar trial characteristic of frozen soil in split Hopkinson pressure bar experiment that reflects unique dynamic mechanical properties.