Investigation of damage characteristics of coral reef limestone under uniaxial compression based on pore structure

The variation of the biological source and diagenetic environment results in significant differences in pore structure and mechanical properties of coral reef limestone (CRL) with various structures. This study analyzed uniaxial compression behavior and pore structural characteristics of four types of CRL using the uniaxial compression test and computerized tomography (CT) scanning test. The influence mechanism of CRL's physical properties on its uniaxial compression characteristics was revealed from a microscopic perspective. The results suggested that the uniaxial compressive curves of different structural types of CRLs exhibited “single-peak” or “multi-peak” characteristics, in which Coral Framework Limestone (CFL) and Coral Boulder Limestone (CBL) mainly experienced brittle failure while Coral Gravel Limestone (CGL) and Coral Calcarenite Limestone (CCL) underwent ductile failure with the increase of porosity. Through a CT scanning test, the influence of pore structure on the damage mechanism of CRL was explored. According to the digital image analysis technique, the influence of CRL diagenesis on the pore fractal dimension was investigated from the perspective of geological genesis, and an empirical formula for estimating uniaxial compressive strength (UCS) of CRL was established based on the fractal dimension. Furthermore, a quality evaluation method for CRL suitable for practical engineering was proposed. The research results can provide a reference for the estimation of UCS and quality classification evaluation of CRL in the construction of island reefs.