Impact-induced fragmentation of coral reef limestone based on fractal theory

Abstract

The reef limestone specimens selected in this experiment can be divided into four types according to their morphologies: strongly-cemented compact-type (BM-type), weakly-cemented compact-type (M-type), weakly-cemented loose-type (BS-type), and strongly-cemented loose-type (S-type). Based on the split Hopkinson pressure bar (SHPB) test, the aims of this study were to investigate the dynamic mechanical response and energy dissipation characteristics of reef limestone under impact loads and discuss the relationships of the dynamic fragmentation fractal characteristics with the strain rate and energy dissipation of reef limestone. The results indicated that the length of the compaction section for compact-type reef limestone compared with that of the loose section, which is more significant in the case of decreasing strain rate. The fractal dimension is linearly positively correlated with the strain rate; the fractal dimension of compact-type reef limestone is lower than that of loose-type reef limestone; meanwhile, the dynamic fractal dimension of compact-type reef limestone is more sensitive to the strain rate. The fragmentation fractal dimension of reef limestone under impact loads shows exponential growth with the increase in dynamic strength. The fragmentation fractal dimension of reef limestone is linearly, and positively, correlated with energy dissipation density.