<p>The mechanical behavior of carbonate rocks under the combined influence of hydraulic and mechanical factors is crucial for ensuring stability in underground mining and tunneling within karst regions. Therefore, investigating the physical and mechanical characteristics of these rocks under such coupled conditions is vital for evaluating and managing the stability of rock engineering projects. This study simulates an acidic karst environment to prepare limestone specimens exhibiting varying levels of erosion and conducts triaxial compression and mercury intrusion porosimetry tests. Results reveal that karst erosion degrades limestone to a certain extent, and pore water pressure accelerates the damage progression, exhibiting clear convergence trends. Using experimental data, the degradation effects induced by chemical and mechanical pressures from karst erosion were quantified through data fitting and Weibull distribution analysis. A constitutive damage model for limestone was then formulated, incorporating karst erosion effects, mechanical stress, and pore water pressure. Based on Lemaitre’s strain equivalence principle and the effective stress principle, the model demonstrated excellent alignment with the experimental data. These findings offer valuable theoretical insights for assessing the mechanical properties and guiding engineering applications of carbonate rocks in karst terrains.</p>