Mechanical properties and multi-factor ANOVA of reef limestone under cyclic loading after temperature-CO2 pressure dissolution

Abstract

Reef limestone, as a crucial geological foundation for marine engineering, faces significant challenges regarding its long-term mechanical stability under complex marine environments. To address the coupled effects of chemical dissolution and periodic wave loading in deep-sea and island reef engineering, this study conducted cyclic loading tests on reef limestone with varying initial porosities after dissolution under different temperature and CO2 pressure conditions. Based on 18 groups of multi-factor orthogonal tests, the macroscopic stress-strain hysteresis characteristics were systematically analyzed, and an Analysis of Variance (ANOVA) was performed using the axial deformation increment as the damage evaluation index. The results indicate that the coupled dissolution of temperature and high-pressure CO2 significantly increases the porosity and weakens the internal cementation of the reef limestone, leading to a substantially accelerated accumulation rate of plastic strain and broader hysteresis loops under cyclic loading. ANOVA quantitatively reveals that at a 95% confidence level, dissolution temperature (P=0.0130), CO2 pressure (P=0.0389), stress amplitude (P=0.0356), and initial porosity (P=0.0395) exert a significant controlling effect on axial cumulative deformation. In contrast, the effect of loading frequency (within the 0.25∼0.5 Hz range, P=0.9605) is negligible, suggesting it can be reasonably simplified in practical low-frequency dynamic load designs. This study elucidates the coupled degradation mechanism of chemical dissolution and fatigue loading, providing essential mechanical parameters and a theoretical basis for evaluating the long-term stability and predicting the service life of deep marine foundations.