Uniaxial compression characteristics of railway ballast combined with ice.

• The compressive strengths of ballast-ice combinations at different freezing temperatures were obtained. • The strength evolution patterns of ballast-ice combinations during compression were explored. • The internal meso -mechanical states of ballast-ice combinations at the failure moment were analyzed. The mechanical properties of railway ballast in a freezing environment are different from those in a normal environment, and these properties need special attention. In this work, uniaxial compression ballast-ice specimens with the same size were made, and the compressive strengths of the specimens for the temperature conditions of –10 °C, –20 °C, and –30 °C were measured using a pressure testing machine. Then the evolution patterns of the compressive strengths of the ballast-ice combinations with temperature were analyzed. The discrete element models for the uniaxial compression tests of the ballast-ice combinations were established, and the meso -mechanical changes of the ballast-ice combinations at different freezing temperatures were analyzed at the failure moment. The results showed that with the decrease of temperature, the compressive strength, and the brittleness of the ballast-ice combinations gradually increased. The main manifestations were as follows. When the temperature was below –10 °C, the compressive strength of the ballast-ice combinations increased with the decrease of temperature (49.150 kPa at –10 °C, 154.625 kPa at –30 °C). The elastic modulus of the ballast-ice combinations increased with the decrease of temperature (5.118 MPa at –10 °C, 29.330 MPa at –30 °C), and their compression distances decreased when the failure occurred (1.96 mm and 1.09 mm). At the failure moment, the ice layer inside the ballast-ice combinations with a higher temperature (–10 °C) was more complete (the number of bonding keys was more than 2400, and the keys were agminated), but the force it could bear was lower (the bonding keys were numerous and concentrated, but their force values were small). When the temperature was lower (–30 °C), the separation was more serious at the failure moment (the number of bonding keys was fewer than 1500), but the overall force that the combination could bear was higher (there were five bonding forces more than 500 N). It is hoped that the test methods of this work can provide a reference for the further study of the mechanical properties of ballast in a freezing environment. [ABSTRACT FROM AUTHOR]