Experimental study on dynamic mechanical properties and damage characteristics of coral reef limestone

The coral reef limestone (CRL) in this study is characterized by well-developed pores, varied density range, and obvious growth line. To investigate the dynamic mechanical properties and damage characteristics of CRL, a series of impact experiments were conducted by employing a split Hopkinson pressure bar (SHPB) device. The effects of growth line inclination, strain rate and density on the dynamic mechanical properties of CRL were analyzed, and their damage characteristics were estimated by a quantitative analysis of the failure patterns. The results show that the stress–strain curve of CRL has a longer elastic stage and a shorter failure stage compared with porous rock-like materials, the porous properties of CRL are not obvious. The dynamic peak stress of CRL with the same density decreases gradually with the increasing growth line inclination. The strain rate effect of dynamic peak stress of CRL has a dependent on density, and the correlation between dynamic peak stress and strain rate becomes more obvious for CRL with higher density. The dynamic peak stress of CRL increases exponentially with increasing density, and density shows a much greater effect on peak dynamic stress compared with the growth line inclination. In addition, CRL exhibits distinct failure patters and fragment morphology from terrigenous rocks. CRL has an obvious fractal characteristic with fractal dimension of 2.09–2.76, which is influenced by growth line inclination, strain rate and density consistent with dynamic strength.