Dynamic compressive characteristics and damage constitutive model of coral reef limestone with different cementation degrees

Abstract

Reef limestone has a heterogeneous, anisotropic, porous structure. According to apparent pore characteristics, shallow reef limestone can be divided into four types: weakly-cemented porous (WP), strongly-cemented porous (P), weakly-cemented dense (WD), and strongly-cemented dense (D) types. On this basis, physical properties including the density porosity, and longitudinal wave velocity of each type of reef limestone and their intrinsic correlations were measured and discussed. The quasi-static and dynamic compression tests were conducted on the four types of reef limestone samples to estimate the correlations of physical properties of reef limestone and its dynamic and static parameters. Results show that reef limestone is different from most terrestrial rocks; its compressive strength is weakly correlated with the strain rate and its static tension–compression ratio is slightly larger than that of terrestrial rocks (about one fifth). The static tensile and compressive strengths as well as the dynamic compressive strength of dense reef limestone all linearly increase with the density; the static compressive strength of porous reef limestone is weakly related to the density while the dynamic compressive strength increases with the elastic longitudinal wave velocity as a quadratic function. The dynamic fracture mode of dense reef limestone is dominated by block failure while strip-shaped fragments are mainly formed along the coral growth line in porous reef limestone. The energy-dissipation density of the two major types of reef limestone is roughly linearly correlated with the dynamic compressive strength. Finally, a constitutive model for dynamic damage of reef limestone under impact load was established based on statistical damage theory and its effectiveness was verified experimentally.