Experimental study on dynamic failure behavior of red sandstone after freeze-thaw cycles

The rock mass in the alpine region is affected by freeze-thaw cycles all year round, and the mechanical properties of rock mass will deteriorate under the impact load such as blasting vibration in the freeze-thaw area, which will affect the safety and stability of rock mass engineering. To investigate the effects of freeze-thaw cycles on the dynamic mechanical properties of sandstone, a separated Hopkinson compression bar test system is used to conduct dynamic impact tests on sandstone specimens with different freeze-thaw cycles, The dynamic mechanical properties, energy dissipation, and fracture fractal characteristics of sandstone specimens during loading with different freeze-thaw cycles and strain rates are analyzed. The experimental results show that the dynamic yield strength of sandstone is positively linearly correlated with strain rate and has a significant strain-rate effect, the energy dissipation rate of sandstone is positively correlated with the strain rate, but the elastic modulus of sandstone does not exist rate correlation with different freeze-thaw cycles. The dynamic peak strength and unit volume dissipation energy show a three-stage decrease with the number of freeze-thaw cycles, while the fractal dimension is the opposite. The decrease of cementation material, the dissolution of some minerals in water and the deterioration of pore structure are the fundamental reasons that affect the macroscopic dynamic mechanical properties of red sandstone. As the number of freeze-thaw cycles increases, ductile failure begins to occur, but the required dissipation energy decreases. The above research results can provide reference for the stability evaluation of rock mass engineering in alpine regions. •The dynamic mechanical properties of freeze-thaw red sandstone are revealed by impact test.•The mechanism of freeze-thaw damage is revealed by XRD and SEM analysis.•The dynamic peak strength and unit volume dissipation energy decrease in three stages with the number of freeze-thaw cycles.