Abstract
The deformation and failure characteristics of red sandstone under subzero temperature were studied by the split Hopkinson pressure bar (SHPB) dynamic impact test. The effects of different subzero temperatures on rock strength properties, fractal dimension, and dissipated energy were analyzed combined with microfracture morphology. The reasons for rock dynamic mechanical property deterioration under lower subzero temperatures were revealed. The research shows that low subzero temperature will cause “frostbite” of red sandstone. Under high strain rate loading, the rock will quickly lose its bearing capacity, and its dynamic mechanical strength will drop sharply. The dissipated energy WL of the frozen rock specimen is positively correlated with the fractal dimension D and closely related to the macroscopic failure characteristics. It could be concluded that greater dissipation energy leads to more serious damage of rock and accordingly results in a larger fractal dimension. Fracture morphology analysis shows that the lower subzero temperature generated remarkable cracks in the material interface of the red sandstone. The damage of the red sandstone could be explained by the fact that the crack tip had low plastic deformation ability under high strain rate loading and the composition of cement was vulnerable to the subzero temperature effect.
Highlights
As geotechnical engineering projects increase rapidly in the high-altitude area, it is of great interest to investigate the rock properties under subzero temperature. e rock will shrink and become dense when it encounters subzero temperature, which seems to increase in strength
Rock under subzero temperature is prone to brittle failure, which makes it difficult to predict the mechanical properties of rock under subzero temperature and high strain loading rate
Aoki et al [3] carried out a quasi-static uniaxial compression experiment and Brazilian splitting experiment on a variety of rocks in the negative temperature region, and the results showed that the compressive tensile strength and elastic modulus of rocks increased significantly at −160°C
Summary
As geotechnical engineering projects increase rapidly in the high-altitude area, it is of great interest to investigate the rock properties under subzero temperature. e rock will shrink and become dense when it encounters subzero temperature, which seems to increase in strength. Aoki et al [3] carried out a quasi-static uniaxial compression experiment and Brazilian splitting experiment on a variety of rocks in the negative temperature region, and the results showed that the compressive tensile strength and elastic modulus of rocks increased significantly at −160°C. E research results show that negative temperature has a great influence on the mechanical parameters of rocks, and the compressive strength, internal friction angle, cohesion, and elastic modulus of rocks increase with the decrease of temperature. After combining analysis with scanning electron microscopy (SEM), the effects of dynamic load, subzero temperature, and water-ice phase transformation on the strength and deformation properties of rock were studied by fractal dimension and fracture morphology
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