Dynamic Mechanical Characteristics and Damage Evolution Model of Granite
Dynamic Mechanical Characteristics and Damage Evolution Model of Granite

By using the technique of the split Hopkinson pressure bar (SHPB), impact tests at different stress wavelengths(0.8-2.0 m) and strain rates (20-120 s-1) were conducted to study the dynamic mechanical properties and damage accumulation evolution law of granite. Test results show that the dynamic compressive strength and strain rate of granite have a significantly exponential correlation; the relationship between peak strain and strain rate is approximately linear, and the increase of wavelengths generally makes the level of peak strain uplift. The multiple-impacts test at a low strain rate indicates that at the same wavelength, the cumulative damage of granite shows an exponential increasing form with the increase of strain rate; when keeping the increase of strain rate constant and increasing the stress wavelength, the damage accumulation effect of granite is intensified and still shows an exponential increasing form; under the effect of multiple impacts, the damage development trend of granite is similar overall, but the increase rate is accelerating. Therefore the damage evolution model was established on the basis of the exponential function while the physical meaning of parameters in the model was determined. The model can reflect the effect of the wave parameters and multiple impacts. The validity of the model and the physical meaning of the parameters were verified by the test, which further offer a reference for correlational research and engineering application for the granite.
By using the technique of the split Hopkinson pressure bar (SHPB), impact tests at different stress wavelengths(0.8-2.0 m) and strain rates (20-120 s-1) were conducted to study the dynamic mechanical properties and damage accumulation evolution law of granite. Test results show that the dynamic compressive strength and strain rate of granite have a significantly exponential correlation; the relationship between peak strain and strain rate is approximately linear, and the increase of wavelengths generally makes the level of peak strain uplift. The multiple-impacts test at a low strain rate indicates that at the same wavelength, the cumulative damage of granite shows an exponential increasing form with the increase of strain rate; when keeping the increase of strain rate constant and increasing the stress wavelength, the damage accumulation effect of granite is intensified and still shows an exponential increasing form; under the effect of multiple impacts, the damage development trend of granite is similar overall, but the increase rate is accelerating. Therefore