Cyclic behaviour of coarse-grained materials exposed to freeze-thaw cycles: Experimental evidence and evolution model.

With the rapid development of high-speed railways (HSRs) in seasonally frozen regions in China in recent years, there is an increasing need for better understanding of how the construction materials behave. In particular, the dynamic behaviours of coarse-grained materials (CGMs) used for China's HSRs subjected to combined actions of cyclic loading and freeze-thaw (F-T) cycles has attracted much attention. In this study, a series of cyclic triaxial tests were performed to investigate the characteristics of CGMs considering the effects of number of F-T cycles (N FT), confining pressures (σ 3), dynamic stress amplitude (σ ¯ d), and fines content (FC). Representative test results of accumulative axial strain (ε acc), resilient modulus (M r), dynamic shear modulus (G d) and damping ratio (D) are then presented and discussed. Empirical models are proposed and validated for predicting the evolution of ε acc and M r for CGMs under the cyclic loading. In addition, the evolution models of G d and D were established, which can be used for computing the response of CGMs under various influencing factors. Overall, this study provides further insights into the cyclic behaviours of CGMs in seasonally frozen regions. • Cyclic triaxial tests were carried out on prepared thawed coarse-grained materials. • Effects of freeze-thaw cycles, confining pressure, dynamic stress amplitude, and fines content were discussed. • Models for accumulative strain, resilient modulus, dynamic shear modulus and damping ratio were proposed and validated. [ABSTRACT FROM AUTHOR]