Mechanical properties of frozen ballast aggregates with different ice contents and temperatures

Abstract

Ice is the main factor that influences the properties of frozen ballast layers. To investigate the mechanical properties of railway ballasted beds in cold regions under freezing conditions, ice–bonded ballast specimens were prepared, and uniaxial compression tests were performed in a negative temperature environment. At a low loading velocity (v = 0.01 mm/s), the effects of the ice content (2%–35%) and temperature (−5 to − 30 °C) were analysed. The experimental results showed that the stress–strain curves exhibited strain-softening characteristics at different ice contents and temperatures. With an increase in the ice content, the ductile characteristics of the frozen specimens improved. The failure mode changed from brittle failure to axial splitting failure. Moreover, the compressive strength increased exponentially, and the effective elastic modulus increased linearly. Temperature significantly influenced the strength and deformation behaviour of the frozen specimens. The lower the temperature, the higher the compressive strength and effective elastic modulus. The relationship between temperature and compressive strength could be expressed using a power function. Finally, an empirical formula for computing the compressive strength of the ice–bonded ballast was obtained, considering the combined effect of the ice content and temperature. This study revealed the mechanical properties and developed a model for predicting the strength of frozen ballast layers in cold regions.