Experimental study on splitting tensile failure characteristics of frozen soils under impact loads

The dynamic tensile strength and failure characteristics of frozen soils have important reference value in the field of efficient crushing and safety stability analysis of frozen soil projects. To study the effects of negative temperature and loading rate on the dynamic tensile properties of the frozen soils, the aluminum split Hopkinson pressure bar system is employed to conduct the dynamic Brazilian disc splitting test of frozen soil. In addition, by using the high-speed camera system, the influences of temperature and loading rate on the dynamic tensile strength, energy dissipation and failure mode of the frozen soils are analyzed. Finally, the splitting failure mechanism of the Brazilian disc and the influencing factors of dynamic tensile strength of the frozen soils are discussed. The results indicate that under the dynamic loads, the Brazilian disc specimens of frozen clay and frozen sand follow the central initiation failure mode, and the specimens are split into two relatively intact halves along the axial direction. With the increase of the impact pressure, the loading rate of two frozen soil types increases linearly, and the duration required for reaching the dynamic tensile peak stress for them is in the range of 92~242 μs. The dynamic tensile strength of the frozen soils shows the obvious temperature effects and loading rate effects, and its values increase with the decrease of the temperature and the increase of the loading rate. There is a good linear relationship between the absorbed energy and the dynamic tensile strength of the frozen soils under various negative temperature conditions. With the increase of the impact pressure, the damage degree of the frozen soil specimens is aggravated, and the triangular fracture zone area caused by high shear stress gradually increases.