Research on Energy Dissipation and Damage Evolution Law of Limestone under Impact Loads

The impact compression test of limestone specimens under different loading rates has been carried out by using the improved split Hopkinson pressure bar（ SHPB） testing apparatus of 50 mm in diameter. Energy dissipation characteristics of limestone specimens in the experiments were analyzed. The laws of the damage of the limestone specimens were analyzed by using the dynamic statistics damage model based on the Weibull random distribution and the stress-strain curves,and the relationship between Dmax and SEA was explored. The results show that transmitted energy,absorbed energy and reflected energy are affected significantly by incident energy,and transmitted energy has the most significant correlation; SEA is significantly increased with the increase of strain rate,and there is a positive linear relation between SEA and strain rate,62.56 s-1 is the critical strain rate when SEA is zero; The dynamic compressive strength and strain rate is exponential function relation; But the energy absorptivity of limestone is greatly reduced with the increase of strain rate. The model curves and the test curves have good consistency,the limestone damage degree increases with the increase of strain,at the peak of stress-strain curve,the damage degree has an inflection point,which means that rock damage rapidly increases in this time; There is a remarkable logarithmical relationship between Dmaxand SEA,and exists a critical SEA when Dmax is zero.