Dynamic Mechanical Properties And Failure Mechanism Of Frozen Soil

This research analyzes the dynamic mechanical properties of frozen soil by the theory of equivalent inclusion, continuum mechanics and impact dynamics theories. Research analyzes the change rule of effective ice content and unfrozen water, and the effect of temperature damage. And this research analyzes the effects of frozen characteristics such as frozen time, frozen sides and impact sides. A series of Split Hopkinson Pressure Bar tests were conducted to analyze the characteristic of stress-strain curves and the causes of strain convergence phenomenon.First of all, this research builds a simple equivalent inclusion model of frozen soil to analyze the energy changes caused by the intrinsic strain. Research analyzes the change rule of fully freezing temperature by energy balance and establishes the fully freezing homogeneous frozen soil model. And the research analyzes the change rule of unfrozen water in ideal conditions and general conditions.Temperature variation is one essential factor of the mechanical properties of frozen soil under impact load. Research supposes the frozen soil is transverse isotropy and analyses the concrete effects of temperature damage by building transient impact surfaces in frozen soil models. Research establishes a partial freezing homogeneous frozen soil dynamic constitutive model after all.Research shows that homogeneous frozen soil or inhomogeneous frozen soil has different dynamic mechanical properties. This research analyzes the fully freezing temperature by theory of equivalent inclusion and establishes the dynamic constitutive model of fully freezing frozen soil. The research analyzes the differences cause by freezing time, temperature fields, freezing sides and impact sides. The research compares dynamic mechanical properties of frozen soil with different freezing sides or impact sides and establishes dynamic constitutive model of partial freezing inhomogeneous frozen soil.The Split Hopkinson Pressure Bar test is the main method to realize the dynamic mechanical properties of frozen soil. Based on the systemic experiments of frozen soil, research analyses the characteristics of the dynamic stress-strain curves, the necessity of phenomenon such as strain rate effect and temperature effect and the effect of initial moisture content of frozen soil in Split Hopkinson Pressure Bar experiments.A strain convergence phenomenon of strain is concluded from the experiment results. The occurrence prerequisite of strain convergence phenomenon is the same high strain rate but not on the freezing temperature and initial moisture content. Moreover, the loading process of Split Hopkinson Pressure Bar experiments is another important factor of the strain convergence phenomenon which determines the convergence position. Generally speaking, the strain convergence phenomenon is a peculiar trial characteristic of frozen soil in Split Hopkinson Pressure Bar experiments. The strain convergence phenomenon reflects the unique dynamic mechanical properties of frozen soil.The theoretical results are compared with the experiments results. It is doubtless that results in this research determine a reliable dynamic constitutive model of frozen soil.