Multi-scale damage and fracture analysis and statistical damage constitutive model of shallow coral reef limestone based on digital core

Abstract

Coral reef limestone (CRL) constitutes a distinctive marine carbonate formation with complex mechanical properties. This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing, digital core technology, and theoretical modelling. Two CRL types with contrasting mesostructures were characterized across three scales. Macroscopically, CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa, respectively. Mesoscopically, CRL-I featured small-scale highly interconnected pores, whilst CRL-II developed larger stratified pores with diminished connectivity. Microscopically, both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties. A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes, revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II. Furthermore, a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior. These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.

Keywords

Coral reef limestone / Multi-scale mechanics / Digital core / Pore structure / Representative volume element / Damage and fracture / Damage statistical constitutive model

Acknowledgments

This research was conducted within the scope of the National Key Research and Development Program of China (No. 2021YFC3100800), the National Natural Science Foundation of China (Nos. 42407235 and 42271026), and the Project of Sanya Yazhou Bay Science and Technology City (No. SCKJ-JYRC-2023-54). The simulation work of this study was supported by the Hefei advanced computing center.

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